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Risk perceptions and knowledge ofbreast cancer genetics in womenat increased risk of developinghereditary breast cancerBettina Meiser a , Phyllis Butow b , Alexandra Barratt c , MichaelGattas d , Clara Gaff e , Eric Haan f , Margaret Gleeson a , TracyDudding g & Katherine Tucker aa Hereditary Cancer Clinic , Prince of Wales Hospital , Randwick,Sydney, NSW 2031, Australiab Medical Psychology Unit , University of Sydney , NSW 2006c Department of Public Health and Community Medicine ,University of Sydney , NSW 2006d Clinical Genetics Service , Royal Children's Hospital , Herston,Qld 4029e Victorian Clinical Genetics Services , Royal Children's Hospital ,Parkville, Vic, 3052f South Australian Clinical Genetics Service , Women's andChildren's Hospital , North Adelaide, SA, 5006g Hunter Genetic Services , Waratah, NSW 2298Published online: 19 Dec 2007.

To cite this article: Bettina Meiser , Phyllis Butow , Alexandra Barratt , Michael Gattas , ClaraGaff , Eric Haan , Margaret Gleeson , Tracy Dudding & Katherine Tucker (2001) Risk perceptionsand knowledge of breast cancer genetics in women at increased risk of developing hereditarybreast cancer, Psychology & Health, 16:3, 297-311, DOI: 10.1080/08870440108405508

To link to this article: http://dx.doi.org/10.1080/08870440108405508

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P.s~chology frrld HfYl//h, 200 I, VOl. 16. pp. 207-3 I I Reprints available directly from the Publisher Photocopying perinittcd by license only

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RISK PERCEPTIONS AND KNOWLEDGE OF BREAST CANCER GENETICS IN WOMEN AT

INCREASED RISK OF DEVELOPING HEREDITARY BREAST CANCER

BETTINA MEISER'.*, PHYLLIS BUTOW', ALEXANDRA BARRATT', MICHAEL GATTAS', CLARA GAFF5, ERIC HAAN6, MARGARET GLEESON',

TRACY DUDDING', KATHERINE TUCKER'. and THE PSYCHOLOGICAL IMPACT COLLABORATIVE GROUP'

'Hereditary Cancer Clinic, Prince cf Wales Hospital, Randwick, Sydney, NSW 2031, Aiistr~iliir

'Medical Psychology Unit, University c?f' Sydney, NSW 2006 'Department o j Public Health and Comtniinity Medicine, University ofsydney, NS W 2006

'Clinical Genetics Service, Royal Children's Hospitrrl, Herston, Qld 4029 Victorian Clinical Genetics Services, Roytrl Children's Hospital, Parkville, Vic 3052

"South Australian Clinicd Genetics Service, Women's and Children's Hospital, North Adelaide, SA 5006

'Hunter Genetic Services, Wcircrtcrh, NSW 2298

( K r c r i t w l 3 I ~ i w ~ i i i / ~ i ~ r , I 999; ~ti,fii~ii/,~~iri~~ 5 Octolwr. 2000)

This multicentre study inve\tigated accuracy of perceived hreast cancer risk and breast cancer gciietics knowledge in 333 women at incrcascd risk of developing hei-editary breast cancer. Only woiiicii who had never bccn affected by breast cancer and approached one of 14 fiimilial cancer clinic\ for advice about their breast cancer risk were asessed prior t o their attendance at the clinic. Eleven percent o l woiiieii underestimated. 57% accurately estimated their risk and 3 2 q overestimated their breast cancer risk. Compared t o accurate estimators. overestimators were younger ( O H = 0.97: 95% CI. 0.95-1 .00; 11 = .OS I ), had higher breast cancer rinxicty levels ( O R = 1.03; 9.5% CI, 1.01-1.0S;p= ,0038) and were iiiore likely to fall into tlir Iowcr breast cancer risk categories ( 1 1 < .OOOI). These findings suggest that an approach that exclusively relies o n conveying tactual information on breast caiicei- risk i s unlikely to succeed in correcting exces\ive risk perceptions. and that i t may be necessary to also address excessive breast cancer anxiety. Furthermore. inany woiiieii at high risk of developing breast cancer have misconceptions about breast ca~icer genetic\. underscoring the value of rrfcrml to cornpruhcnsive specialist counselling services.

KEY WORDS: Hereditary breast cancer. risk pcrccption\. genetics knowledge.

INTRODUCTION

Evidence from epidemiological studies has been accumulating to establish a family history of breast cancer as the strongest known risk factor for breast cancer (Goldgar et al., 1996). Up to 20% of women have a family history of breast cancer. A smaller group of women have a family history consistent with a hereditary breast cancer syndrome, which includes the

*Corresponding author. 'Collaborators listed at end of paper.

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’98 R. MEISER E 7 A L .

occurrence of breast and related cancers in multiple members of two or more generations and presentation of breast cancer at an early age. These women are at significantly increased risk of developing breast cancer. The cloning of the two dominantly inherited breast cancer genes, BRCAl and BHCA2, has made possible susceptibility testing of unaffected individuals (Goldgar et al., 1996). The estimated risk of breast cancer by age 70 associated with mula- tions in BRCAl and BRCA2 is between 56% and 85% (Struewing et nl., 1997; Whittemore et al., 1997), with the lowest estimate referring to risk imparted by BRCAI mutations common in Ashkenazi Jewish women (Struewing et al., 1997). It is to be expected that conventional models of genetic counselling will be affected by the increasing availability of genetic testing for breast cancer susceptibility. Traditionally genetic counselling has been concerned with communicating information about genetic risk largely within the context of reproductive decision-making. Given the complexity of the information to be conveyed and its potential impact on decision-making about screening and prophylactic strategies, i t appears crucial to understand women’s knowledge of breast cancer genetics and their risk perceptions.

Such assessment is likely to enhance the effectiveness of genetic counselling by revealing misconceptions and highlighting areas that need to be addressed during genetic counselling. Investigation of the sociodemographic and psychological determinants of accuracy of perceived risk and breast cancer genetics knowledge allows the identification of women most likely to have misconceptions about their risk, thereby assisting with the precise targeting of interventions aimed at correcting risk perceptions.

Most theories which seek to explain health beliefs and screening behaviours, including the Health Belief Model, the Transactional Model of Stress and Coping and Self-Regulation Theory, emphasise perceived risk or susceptibility as a key dimension underlying compliance with screening recommendations and preventative behaviours (Lazarus. 199 1 ; Leventhal, 1989). The Transactional Model of Stress and Coping, for example, emphasises the import- ance of primary appraisal (such as perceived susceptibility) and secondary appraisal (for example perceived control over emotions) in determining adaptation to potential threats (Lazarus, 199 I ).

The importance of perceived risk is supported by several studies which have provided data on the emotional and behavioural consequences of inaccurate risk perceptions. Firstly, women who overestimate their risk consistently have been shown to be more vulnerable to breast cancer worry (Watson et al., 1999). Moreover, perceived risk has been found to be associated with excessive breast self-examination (Epstein ef al., 1997), and it is possible that overestimating one’s risk may also be associated with overutilization of niammographic screening, given the well-established association between perceived risk and breast cancer screening uptake (McCaul e ta / . , 1996).

Finally, we found that considering prophylactic mastectomy strongly correlates with overestimating one’s breast cancer risk (Meiser et NI., 2000a). While it is understandable if high-risk women consider mastectomy in an attempt to reduce both their breast cancer risk and anxiety level, it is of concern if women’s decision-making is based on inaccurate risk perceptions.

Table 1 summarises previous studies that assessed accuracy of perceived breast cancer risk in women with a family history of breast cancer prior to counselling interventions, if any. While several studies assessed awareness of increased risk in women with a family history compared to women in the general population (Audrain et al., 1995; Hughes et i l l . ,

1996), only one study is available on the determinants of accuracy of perceived risk (Daly ef d., 1996). Daly et al. found that overestimating one’s breast cancer risk was associated

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RISK PERCEPTIONS IN WOMEN AT INCREASED RISK 299

lahle 1 Studies on accuracy of breast ca~iccr risk percepiions amongst wonicn with a family history of brea\t cancer

Stu11,. Pf~/~u/trriOrl N % Uirdrr- % ( iuxrore c/r Ovrr- 1, s f l l l l ~ l t ~ l ~ , ~ PSfi l?l t l l i l l ,q

Daly er a/.. I996 First-clcgrce relatives of index c i~sch 960 3 I I 86 Lcrrnan r f d.. 199% I-'irst-degrce relatives of index ci~scs 2 0 0 2 0 X9

Kash ercd., I996 Medium & high-risk wonieii in 503 5 15 80 participating in risk counselling trial

surveillance program

familial cancer clinic

I998 familial ciniccr clinic

familial c:inccr clinic

familial cancer clinic

familial cancer clinic

Evans ('I ( I / . , 1993 Medium& high-risk wnnien attending IS5 48 I I 41

I-iopwood Y l d. , Medium & high-risk wonicn attending IS8 44 38 I X

cull ( ' I N / . . 1998 Mediuin & high-risk women attending I7X 27 5 0 I4

Watson C I d. I999 Medium & high-risk wonien attcnding 282 39 9 57

Cull l'f o/., 1999 Medium & high-risk women attciiding 450 39 47 14

with being Caucasian, and older women were less likely to overestimate risk (Daly et ul., 1996).

The study by Daly et (11. made an important contribution to the literature (Daly et nl., 1996). However, the sample included was unlikely to be representative of women with a strong family history of breast cancer, in that the majority of women included had just one first-degree relative with breast cancer (Daly et a/., 1996). Since it is possible that having a strong family history, rather than simply being aware of having a family history, may affect associations between predictors and accuracy of perceived risk, our study aimed to assess the sociodemographic and psychological determinants of accuracy of perceived risk in a large sample of unaffected women with a strong family history of breast cancer. We hypothesised that overestimating one's risk would be associated with breast cancer anxiety.

While several studies have examined levels of breast cancer genetics knowledge among women with a family history of breast cancer (Cull et a/. , 1998; Hughes et al., 1997; Lerman et cd., 1997; Lerman et d., 1996a; Wonderlick and Fine, 1997). only one study assessed predictors of breast cancer genetics knowledge (Hughes et nl., 1997). Women who had been recruited to the study through self-referral had higher mean knowledge scores than participants recruited through affected index patients, and knowledge was associated with being married and educational level (Hughes er d., 1997).

PATIENTS AND METHODS

Pa rticiputi t s

Data were collected as part of a more comprehensive assessment of attitudes to genetic testing (Meiser et nl., 2000a), screening uptake (Meiser et al., 2000c), and attitudes to prophylactic surgery (Meiser et d., 1999; Meiser et nl., 2000b). The findings reported here are based on a sample of 333 unaffected women with a family history of breast cancer. Women who approached 1 of 14 familial cancer clinics and six associated outreach clinics in five Australian States (New South Wales, Victoria, South Australia, Queensland and Western Australia) between November 1996 and January 1999 were eligible for participation. These

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300 B. MEISER E 7 A l . .

familial cancer clinics provide a comprehensive service which includes risk assessment, genetic testing and advice regarding early detection and prophylactic strategies (Kirk and Tucker, 1997). Women were considered ineligible for study participation if they had a prior diagnosis of ovarian or breast cancer; were unable to give informed consent; or had limited literacy in English, since data were collected using self-report questionnaires. The study was approved by 16 institutional ethics committees.

Familial cancer clinic staff invited women to participate in the study during the pre-clinic telephone call before initial face-to-face counselling. Questionnaires, consent forms and reply-paid envelopes were then mailed out by the co-ordinating research centre. Women were subsequently telephoned by the central research staff and given further information about the study and issues of informed consent. Participants were asked to return the completed questionnaire and consent form before attending the familial cancer clinic. Reminder calls were made as required.

Mecisinres

Dernngruphic characteristics. Sex, age, educational level, marital status and number of biological children were assessed.

I n p i c t of Event Sccile. This 15-item scale is a validated scale that measures intrusive thoughts and avoidant thinking about a specific stressful event (Horowitz et al., 1979: Zilberg Pt al., 1982). Individuals at increased risk of developing hereditary breast cancer may construe their being at risk as a continuous, rather than specific, trauma. Although the scale has not previously been specifically validated among individuals at high risk of developing breast cancer, it has been used in several studies as a measure of breast cancer anxiety (Lerrnan et al., 1993; Lerman et al., 1995b) and previously has been shown to be predictive of interest in genetic testing (Croyle and Lerman, 1993). In the current study the particular stressor was concern about being at risk of developing breast cancer. Participants were asked to rate symptoms of anxiety (for example, ‘I had strong waves of feelings about being at risk of breast cancer’) on a scale ranging from ‘Not at all’ to ‘Often’.

Ohjertive breast cnncer risk. To provide an estimate of objective risk, clinic staff were asked to make a judgement on whether a participant’s family history was either consistent or not consistent with a dominantly inherited predisposition to breast cancer, and participants were thus classified as being at ‘high risk’ or ‘moderately increased risk’ respectively (National Breast Cancer Centre, 1997). Thus women at ‘moderately increased risk’ had a family history of breast cancer suggesting that their risk was increased (lifetime risk of 1 in 4 to 1 in 8) relative to women at average risk, without suggesting presence of a dominantly inherited predisposition of cancer (lifetime risk of 1 in 2 to 1 in 4). Following the risk assessment interview at the familial cancer clinic and once pedigree information (Easton er d., 1993; Ford et d., 1994) and relatives’ diagnoses confirmed by medical records were available, clinic staff categorised participants into objective risk groups. For women at high risk, clinic staff made a judgement on whether the participant was at either 50% or 25% mutation carrier risk. An approximate 25% mutation carrier risk would apply to a woman from a high-risk family whose closest affected relative is second degree; or to a woman from a family with an identified mutation whose closest relative of known mutation status is second degree. A woman from a high-risk family whose closest affected relative is first

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RISK PERCEPTIONS IN WOMEN AT INCREASED KlSK 30 I

degree; or a woman from a family with an identified mutation whose closest relative of known mutation status is first degree was classified as being at 50% mutation carrier risk. This was done because of the current uncertainty associated with risks imparted by breast cancer gene mutations and the inappropriateness of the Claus and Gail models to high-risk women (Claus et al., 1994; Gail et al., 1989). The expert opinion of clinical geneticists was used as a gold standard, since there are currently no universally accepted standards to estimate breast cancer risk in high-risk women. Number of first- and second-degree relatives who developed breast or ovarian cancer were collected from study participants.

Breast cancer risk perception. One item asked participants to select their approximate perceived lifetime breast cancer risk from the following response options: 1 %, 496, 876, 12%, 16%, 25%, 33%, 50%, 85% and 100%. Risk was expressed both as a percentage and as odds (e.g. 1 in 8).

Breast Cancer Genetics Knowledge Scale. This nine-item true-false measure assesses knowledge about breast cancer genetics. The scale is a revised version of a measure previ- ously used in a study on the psychological impact of BRCAl testing (Lerman etal. , 1996a). The wording of the original items specifically referred to BRCAl testing and thus required revision, since the BRCA2 gene had already been cloned when data collection for our study commenced. One point was given for each correct answer (range 0-9). The scale was found to have moderate internal consistency in the current sample with a coefficient (I of 0.59.

Statisticcd Analysis

Accuracy of perceived risk. A new variable was created which classified women in terms of their accuracy of risk perception, namely as underestimators, accurate estimators or overestimators. Classifications were based on geneticists’ estimated risks and women’s risk perceptions. The best estimate of lifetime breast cancer risk in high-risk women was based on the assumption that breast cancer gene mutations are dominantly inherited and that the real penetrance rate imparted by mutations is 60%. For women whose family history did not suggest a dominantly inherited predisposition to breast cancer (‘moderately increased risk’ group) and high-risk women at 25% mutation carrier risk, a breast cancer lifetime risk of 1 in 6 was used as a benchmark. and for women at 50% mutation carrier risk, a breast cancer risk of 1 in 3. Participants whose estimate of their own risk fell either one response option below or above the category used as a benchmark were categorised as accurate estimators, and overestimators above and underestimators below them.

For illustrative purposes, the breast cancer anxiety variable was re-coded into breast cancer anxiety levels (low. moderately low, moderately high and high), using quartiles as cut-off points. To assess bivariate associations with accuracy of perceived risk, x’ analyses were carried out with objective risk, educational level and breast cancer anxiety level. Kruskal-Wallis tests were performed with the non-normal interval variables of number of first- and second-degree relatives with breast or ovarian cancer and total breast cancer genetics knowledge scores. A one-way analysis of variance was used for the normally distributed variable of age. Two logistic regressions were performed to assess independent predictors of accuracy of risk perception. The first regression included underestimators and accurate estimators, and the second accurate estimators and overestimators. Independent variables with bivariate associations significant at p < . I (age, breast cancer anxiety and objective risk) were entered into each regression equation.

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302 B. MEISER E T A L .

Breast cancer genetics knowledge. Descriptive statistics were used to calculate the number and percentage of correct knowledge items. An overall breast cancer genetics knowledge score was calculated for each respondent by summing the number of correct responses to each of the nine items of the scale. 'Don't know' responses were categorised as incorrect responses. To assess bivariate associations with breast cancer genetics know- ledge, Mann-Whitney U-tests were performed for marital status and referral source (self- referred vs. other). Because the knowledge for breast cancer genetics variable did not satisfy normality assumptions, Spearman's rank, rather than Pearson's correlations, were calculated for the following variables: age, educational level and number of first-and second-degree relatives with breast or ovarian cancer. Independent variables with bivariate associations significant at p < . I were entered into a multiple regression equation.

RESULTS

SLirnpIe Churcicteristics

Of the 374 women who met the eligibility criteria, 41 women declined participation or ncver returned the questionnaire (response rate of 89%). Table 2 summarises sociodemo- graphic and family history variables of the study sample. The median age of the sample was 39 years, ranging from 18 to 75. Sixty-nine percent had post-school qualifications, compared to 37% of women in the general Australian population (Australian Bureau of Statistics, 1997).

The mean age of breast cancer onset in the youngest person in the family was 41 years ( S D = 9.6). The number of self-reported first- and second-degree relatives with a diagnosis of breast or ovarian cancer ranged from I to 18, with a median of three. All women were assessed prior to their attendance at the familial cancer clinic. Clinic staff judged 67% of

Table 2 Sociodct~ioarapliic m d family history variables of study saniple ( N = 3 3 3 )

Mnrital status

Biological children

Educational level

l ~ ~ l l l l l l ~ /l;.Y/ory l ~ l l f l ~ l l ~ l f Y

0h.jcctive risk

N o . ofFDR 1G SDR with hreast oi owriat i ciincer.l'

Accuracy of risk perception

< 30 30-39 40-49 S O + Married Not married Yes Nu Post-school qualifications N o i~ost-sch~ool ciu:ilificarion\

Moderate risk High risk - 2.5%' MCK" High risk - SO% MCII" I-?

3 4 5-IX U tiderestinlators Accurate estimators Overcstiniators

64 I9 114 34 93 2x 62 I0

217 65 I t 6 35 247 74

X6 26 213 69

O h 31

68 22 3.5 I I

207 h7 lox 3x

118 JI 62 21 33 I I

175 57 09 32

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RISK PERCEPTIONS IN WOMEN AT INCREASED RISK 303

35

30

2s

20

IS

10

S

0 - -. a

i -. a m N

- -. a L (r

i -. a 00

L -. a &

i -. a (r

L _. a N

00 m $

3 (D

(D 2. Y

Figure 1 Perceived breast cancer risk ( N = 3%)

participants to be at high risk and 50% mutation carrier risk, and 1 1 % at 25% mutation carrier risk. The remaining 22% were thought to be at moderately increased risk of developing breast cancer. Fifty-four women (16%) had a family history which included ovarian cancer in addition to breast cancer. The mean breast cancer anxiety score was 15.1 (SD= 14.7). Twenty-eight women (8%) had scores of 40 or higher on the Impact of Event Scale, sug- gesting presence of a significant stress response in relation to being at risk of developing breast cancer (Cella et a/., 1990).

Accuracy of Risk Perception

Figure 1 shows the percentages of participants who endorsed each brezst cancer risk category. When women were classified with respect to accuracy of perceived risk perceptions, 11 %, 57% and 32% were found to underestimate, accurately estimate and overestimate their risk respectively.

Figure 2 shows accuracy of perceived risk by objective risk, and Table 3 presents the results of bivariate analyses on the association between accuracy of perceived risk and predictor variables. Women in the lower risk categories (moderately increased risk and 25% mutation carrier risk) had similar proportions of women overestimating their risk (53% and 46% respectively) and were significantly more likely to overestimate their risk, compared to women in the highest risk category (25% overestimating their risk). Compared to accurate estimators, overestimators were younger ( F = 8.03; p < ,000 1 ), had higher breast cancer anxiety levels ( J = 12.30; p = .002) and were more likely to fall into the lower breast cancer risk categories ( y' = 25.4 I ; p < .OOO I ). Neither educational level ($ = I .40; p = S O ) , number of first- and second-degree relatives (\' = I .89; p = .39) nor total breast cancer genetics knowledge ( y'= I .64; p = .44) were significantly associated with accuracy of risk perception.

As expected, the first logistic regression (underestimators vs. accurate estimators) showed that neither objective risk ( p = .95) nor breast cancer anxiety ( p = .65) were associated with

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304 B. MEISER E7AL..

I1 nderestirna to n Accurate estimators

Overestirna ton

Figure2 Accur;icy of risk perccplion hy objective risk ( N = 306).

accuracy of perceived risk. Age was significantly and negatively associated with accur- ately perceiving one's risk (OR= 0.95; 95% CI, 0.92-0.99; p = .0062).

Table 4 shows the results of the logistic regression comparing accurate estimators and overestirnators. Breast cancer anxiety exhibited a strong association with overestimating

Table 3 Factors associated with accuracy of hrenst cancer risk perceptions

Vrl)'iohlr LPl'Pl N" Pl~rlvlltcJ,ql~ \ - P ol~e~eestii , lt ito,s

Educ;itionnl l r v r l

Breast c:incer anxiety

No. of FIIR CG SDK'

Total hreast cancer Genetics knowledge

Moderate risk 25% MCR" 5 0 8 M C R ~ N o post-school Post-school

Clnderestimator Accurate cstiniator Overestimator Untleresti inator Accurate estini:itor Overestimator Underestimator Accurate estimator Overestimator Underesti niator Accurate cstimutor Overestimator

67 35

203 90

205

33 I74 99 32

I72 97 29

I49 87 32

I73 97

52.5 25.41 < 0 000 I 45.0 24.7 32.7 I .40 0.50 32.3

Metrn csn, \ I 0 ) ' F 45.9 X.03 < 0.000 I 40.0 37.3 13.7 12.30 0.002 13.2 17.7 4.0 1.89 0.39 3.4 3.3 5.3 I .h4 0.44 5 .4 5. I

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RISK PERCEPTIONS IN WOMEN AT INCREASED RISK

Table 4 Logistic regression on overestimators and xcuriitc estimators ( N = 300)

305

~

320. 12 ( / J < ,0001 ) Objective risk Moderate risk & 25% 4.77h 2.70. x.43 <0.0001

Age 0.97 0.94. 0.99 0.008 Breast cancer anxiety

Moderately low 3.80" I .hO, 9.02 0.003

MCR" 50% MCR"

< 0.000 I

Moderately high 1.24 I .80.9.99 0.001 High 6.24 2.66. 14.65 <0.0001 Low

"MCR = Mut;ilion carrier risk; "OR = Odd5 ratio r c l w to comp;wi\ons wiih the c;ncgory li\tcd i ~ i s t ,

one's risk (p < .0001), independently of age and objective risk. Compared to women with low levels of breast cancer anxiety, those with moderately low (OR= 3.80; 95% CI, I .60- 9.02; p = .003), moderately high (OR = 4.24; 95% CI, 1.80-9.99; p = .OO 1) and high levels (OR = 6.24; 95% CI, 2.66-14.65; p < ,0001) were significantly more likely to overestimate their risk. Age was significantly and negatively associated with accurately perceiving one's risk (OR = 0.97; 95% CI, 0.94-0.99; p = .008). The association between objective risk and accuracy of perceived risk was highly significant @< .0001), with women at moderately increased risk and 25% mutation carrier risk being more likely to overestimate their risk, compared to women at 50% mutation carrier risk.

Breast Cancer Genetics Kiiowledge

Figure 3 shows the percentages of participants who responded correctly to false knowledge items, for example 'Breast cancer is always inherited', and Figure 4 displays correct

( 1 ) Maininography \viII always detect hreast cancer

Breast cancer is always inherited

I l a woinaii IooLs Iihe, or has the personality 01'. a rclativc \+ho has or has

had hrcast cancer. the woiiian is likely to have inherited the gene

All Noinen who have the gene for hreast cancer \viI I get breast cancer

A genetic test for breast cancer wi l l also detect other abnorinalities

( 2 )

( 3 )

(1)

( 5 )

0 20 40 60 80 I00

Figure 3 Pcrccntagcs responding correctly to false breast ciiiiccr genetics knowledge itcms

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306 B. MEISER E T A L .

(6 I Men can carry ii gene for hreurl caiiccr

A women who docs in01 have 811 altered gene can still get breast cancer

(71

(8) There I S inorr tliaii one gene that can breast cancer

'I he gei i~ for hrraal caiicrr can also increase [hc risk for ollier caiicers

( Q l

0 20 40 60 80 100

Figure 4 Percentages responding correctly to truc breast cancer genetics knowledge itcins.

responses to true items. For all items the percentages responding correctly ranged from 24% to 85%. Most women responded correctly to items two (80%) and seven (65%), both of which assessed awareness of sporadic breast cancer. Eighty-five percent knew that mammography would not always detect breast cancer (item one). Item four assessed know- ledge of incomplete penetrance of breast cancer gene mutations and was answered correctly by a majority of women (60%). By contrast, fewer women knew that there was more than one breast cancer gene (item eight, 31%) and that breast cancer gene mutations can also increase the risk of other cancers (item nine, 35%).

The total breast cancer genetics knowledge score ranged from 0 to 9, with a mean of5.26 (SD = 1.92). In bivariate analysis, educational level was significantly associated with breast cancer genetics knowledge ( r = -0.2 19, p < .0001). Having self-referred was also signific- antly associated with knowledge ( z =-2.276, p = ,023). Women who had self-referred had significantly higher mean breast cancer genetics knowledge scores (mean = 5.64, SD = 1.90), compared to those who had not self-referred (mean = 5.07, SD = 1.91 ). Age exhibited a negative trend towards significance with knowledge (r=-0.097, p = .080). Neither number of first- and second-degree relatives with breast or ovarian cancer (r=-0.010, p = 36) nor marital status ( z = - I .6 I , p = . I I ) were associated with knowledge.

Table 5 shows the results of multiple regression for breast cancer genetics knowlcdge. The relationship between educational level and breast cancer genetics knowledge was highly significant ( t= 3.74, I-, < .0001). Having self-referred also remained significant (t=-2.00,p= .047). Age was not significantly associated with knowledge (t=-0.78,11= .17).

Table 5 Multiple rcgressicin predicling breast cancei- genetics knowlcdgc ( N = 302)

Educational lcvel 0.24 0.2 I I 0 . I 13. 0.366 3.74 < 0.OOOI Age -0.014 -0.078 -0.034, 0.006 -1.39 0.17 Keierrnl source -0.47 -0. I 12 -0.934. -0.006 -2.00 0.047

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DISCUSSION

Accuracy o j Risk Perception

Our study showed the second highest percentage of women (57%) who accurately estimated their breast cancer risk reported in the literature, with 32% overestimating it. Previous studies involving women with a family history of breast cancer found that the percentage of women accurately estimating their risk ranged between 9% and 59%, and that of those overestimating their risk between 14% and 89% (Cull et NI., 1998; Daly e t a / . , 1996; Evans et al., 1993; Hopwood e t a / . , 1998; Kash. 1996; Leman et al., 199%). Two studies assessed risk perceptions of first-degree relatives of index patients with breast cancer and found that 86% and 89% of women overestimated their risk (Daly e t a / . , 1996; Lerman et d., 1995a). The majority of women participating in these two studies were at average or moderately increased, rather than high, risk of developing breast cancer. We also found that women at moderately increased risk and 25% mutation carrier risk (with an approximate lifetime risk of 1 in 6) were significantly more likely to overestimate their risk, compared to women at 50% mutation carrier risk (approximate risk of 1 in 3).

There are several possible reasons to account for differences in findings between studies. Studies vary in terms of the risk models they employ to assess women’s breast cancer risk. Several studies used the CASH model to estimate risk (Cull e f ol., 1998; Evans et al., 1994; Hopwood e f ~ l . , 1998; Kash, 1996) and two the Gail model (Daly et ul., 1996; Lerman et d., 1995a). The latter studies, both of which were carried out in the United States, found that large proportions of women overestimated their risk (Daly ef a/., 1996; Lerman e t a / . , 1995) . It has been suggested that the Gail model tends to underestimate risk in women with a family history of breast cancer (Hoskins e t a / . , 1995; Kirk and Tucker, 1997). There- fore, it is conceivable that the findings of the two studies which used the Gail model reflect its tendency to underestimate risk (Kash, 1996).

It is also possible that findings demonstrate true differences between samples, rei-lecting culture-specific differences and/or varying sociodeniographic and psychological charac- teristics of samples. Moreover. it is plausible that accuracy of risk perceptions changes over time, as a result of public education campaigns and media exposure. Varying results may also reflect differences in the way accuracy of responses is scored, with error margins varying between 10% (Daly e f al., 1996) and 50% (Evans et a/. , 1994; Hopwood et a/., 1998) of counselled risk.

The cross-sectional design of the study prevents interpretation of the causal nature of the associations ascertained. Nonetheless, our findings suggest that the development of exag- gerated risk perceptions is most likely in women with a relatively low risk of breast cancer and those with high breast cancer anxiety. In the same sample of women, we found that overestimating one’s risk was strongly associated with intention to undergo prophylactic mastectomy (Meiser et d. , 2000b). Given the potential impact of risk perceptions on decision- making about prophylactic surgery, it may be advisable to routinely assess risk perceptions and target interventions at women with a relatively low breast cancer risk and those with high breast cancer anxiety.

Breast cancer anxiety and overestimating one’s risk were highly correlated, even when objective risk was controlled for. This association corresponds to the well-established rela- tionship between emotions (e.g. anxiety) and cognitions (e.g. perceived risk). Strong emotions may interact with cognitive representations of health threats and impact on perceived risk (Leventhal, 1989). The association between breast cancer anxiety and overestimating one’s

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30X B. MEISER KrAL.

risk suggests that it may be necessary to both address excessive breast cancer anxiety and convey factual information on breast cancer risk to decrease inflated risk perceptions. An approach that exclusively relies on information giving is unlikely to succeed in correcting excessive risk perceptions. Breast cancer anxiety has been shown to interfere with compre- hcnsion of risk information (Lerman et al., 1995a), thereby giving further support to an approach that combines information giving and interventions aimed at reducing breast cancer anxiety. There is an increasing amount of evidence that breast cancer risk counselling leads to improvements in perceived breast cancer risk (Cull et ul., 1999; Evans et al., 1994; Watson et id., 1999). Cognitive-behavioural coping skills training, such as a brief problem-solving training intervention, appears to be an effective method of reducing anxiety amongst high- risk women who utilize the techniques regularly (Schwartz er al., 1998).

Results demonstrated that the likelihood of overestimating one’s risk decreased with increasing age. This confirms similar findings from a previous study (Daly et d., 1996). Since educational level was not significantly associated with accuracy of perceived risk, differences in educational level are unlikely to account for this age effect. It is possible that generational effects exist which account for these differences. Women of different ages are likely to differ in terms of their cultural experiences and exposure to health education and information about genetics. In particular, i t is possible that younger women have been exposed more strongly to the recent media attention on breast cancer genetics, which might have given rise to exaggerated risk perceptions.

Breast Cuncer Genetics Knowledge

Our findings on breast cancer genetics knowledge are remarkably consistent with those obtained in studies involving first-degree relatives of index cases (Hughes et ol., 1997; Wonderlick and Fine, 1997) and individuals from families with BRCAl-linked hereditary breast cancer (Lerman et ul., 1996a). Thus women who approach familial cancer clinics were only moderately knowledgeable prior to genetic counselling. Although consistent with findings from overseas studies, these findings are nonetheless surprising. Most women reported having been aware for an extended period (median of seven years prior to attending the familial cancer clinic) that their breast cancer risk was elevated. It is therefore likely that the majority of women had repeated exposure to opportunities aimed at increasing knowledge, whether through communication with other family members, general practitioners and specialists, or through media exposure and self-motivated research activities.

A sizeable proportion of women were unaware of modes of inheritance, incomplete penetrance and population risk of developing breast cancer. Only 35% of participants knew that breast cancer gene mutations may also increase the risk for other cancers. The data also demonstrated that 15% of participants thought that mammography would always detect breast cancer. The latter finding suggests that some women have misconceptions relating to the sensitivity of mammography, and may therefore rely too heavily on mammographic screening, rather than other screening or prophylactic strategies. These findings underscore the importance of specialist counselling for these women. General practitioners may also need education to ensure appropriate referrals.

Perhaps not surprisingly, educational level was positively associated with knowledge, thereby confirming previous results (Hughes et NI., 1997; Wonderlick and Fine, 1997). This finding suggests that women with lower educational levels have much to gain from genetic counselling in terms of improving their knowledge levels. Contrary to previous findings, neither marital status nor number of first-degree relatives and second-degree

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RISK PERCEPTIONS IN WOMEN AT INCREASED RISK 309

relatives were associated with knowledge (Hughes et al., 1997). It is not clear why this is so. Lack of significance may be accounted for by differences in population sociodemographic or family history characteristics.

The moderately high levels of breast cancer genetics knowledge ascertained suggest that there is considerable scope for improvement of women's knowledge levels, and therefore that patient education should be considered an essential component of the management of women at increased risk of developing hereditary breast cancer. By providing individual- ised patient education, genetic counselling may raise understanding of breast cancer genetics, and may thereby also indirectly assist in improving management of patient anxiety levels, as has been suggested by previous research (Lerman et ul., 1996b).

Two limitations of this study should be noted. The high educational levels in the current study sample suggest that generalisations to the broader population of women at increased risk of developing hereditary breast cancer need to be made cautiously. Nonetheless, due to the high participation rate (89%), findings are highly relevant to those women who are most likely to seek information about their breast cancer risk from familial cancer clinics. Secondly, due to the cross-sectional design of the current study, the data cannot confirm the causal direction of the association between, for example, perceived risk and breast cancer anxiety.

Acknowledgements

The authors would like to thank the following individuals for their contributions to this study: Professors Robert A. Boakes and Stewart Dunn for their methodological advice; Dr. Maggie Watson, for generously discussing similar work; and Dr. Jack Chen for statist- ical advice. Finally, we are most grateful for the valuable contribution of all the women who participated in this study. This research was supported by Project Grants No. 970929 and 1 13877 from the National Health and Medical Research Council of Australia.

'Psychological Impact Collaborative Group

The members of the Psychological Impact Collaborative Group are in alphabetical order of group, institute or location: Department of Clinical Genetics, Liverpool Hospital (A. Colley); Familial Cancer Service, Westmead Hospital, Sydney (J. Kirk and M. Smith); Hereditary Cancer Clinic, Prince of Wales Hospital, Sydney (M. Clifton, M. Friedlander, M. Gleeson, V. Schnieden, B. Thewes, K. Tiller and M. Tucker); Hunter Genetics, Newcastle (B. Burgess, T. Dudding and G. Turner); Peter MacCallum Cancer Institute, Melbourne (M.A. Young); Queensland Clinical Genetics Services, Brisbane (M. Gattas, A. Hattam, H. Hopkins, L. Stace and J. White); South Australian Clinical Genetics Services, Adelaide (A. Baxendale, S. Daly, E. Haan, G. Suthers, E. Thompson and S. White); Victorian Clinical Genetics Services, Melbourne (A. Bankier, K. Aittomaki, C. Gaff and M. Gardner); University of Sydney (A. Barratt and P. Butow); Western Australian Clinical Genetics Services (D. Elliot, J. Goldblatt, K. Harrop and I . Walpole).

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310 B. MEISER E T A / .

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