Reactions 824 - 21 Oct 2000

Increased risk of breast cancerwith OC use in at-risk women

Oral contraceptive (OC) use may be associated with asignificantly increased risk of breast cancer in womenwho have a strong family history of the disease,according to the findings of a US study.1

The cohort study investigated the incidence of breastcancer in female family members (3396 blood relativesand 2754 marry-ins) of 426 women who werediagnosed with breast cancer between 1944 and 1952;568 women were lost to follow-up.

Overall, ever-use of OCs was reported by 51% of thestudy cohort (average duration of use was 7 years; range0.5–37.5) and the rate of use was similar for both bloodrelatives and marry-ins. Current OC use was reported by6.5% of ever-users. During the follow-up period after1952 (mean duration 36.6 years), 153 of the bloodrelatives and 86 of the marry-ins developed breastcancer. Compared with never-users, the overall relativerisk (RR) of developing breast cancer for ever-users ofOCs was 1.4 (95% CI 1–2) and did not differ significantlywith the duration of OC use.

Risk greater in high-risk familiesAnalysis by relationship to breast cancer proband

revealed that while granddaughters, nieces and marry-ins did not have an increased risk of breast cancer withOC use, sisters and daughters who were ever-users ofOCs had a significantly higher risk of developing breastcancer than sisters and daughters who had never usedOCs (RR 3.3; 95% CI 1.6–6.7). Additionally, an analysisof 132 high-risk families (defined as ≥ 3 blood relativesdiagnosed with breast or ovarian cancer) revealed a RRfor developing breast cancer of 4.6 (95% CI 2–10.7)among sisters and daughters who had ever-used OCs,while analysis of 35 very high-risk families (≥ 5 bloodrelatives with breast or ovarian cancer) revealed a RR of11.4 (2.3–56.4) for such women.

Only seen with OC use prior to 1975An increased risk of developing breast cancer (RR 3.3;

95% CI 1.5–7.2) was seen for women who had usedOCs prior to 1975, when the dose of estrogen andprogesterone in OCs was higher. Although no increasedrisk of breast cancer was seen in first- or second-degreerelatives or marry-ins who used OCs after 1975, thestudy researchers say that they are ‘hesitant to drawconclusions about the influence of more recent OCformulations on breast cancer risk in women with a first-degree family history of breast cancer’.

Commenting on the study, Dr Wylie Burke says that itprovides important information about the risk of breastcancer associated with OC use, but while the findingsargue for the avoidance of OC use, OCs are an attractiveoption for reducing ovarian cancer.2 He further says that‘the use of OCs needs to be considered on an individualbasis, taking into account baseline risk for breast andovarian cancer, alternative strategies for cancer riskreduction, and other benefits OCs may provide.’1. Grabrick DM, et al. Risk of breast cancer with oral contraceptive use in women

with a family history of breast cancer. JAMA: the Journal of the AmericanMedical Association 284: 1791-1798, 11 Oct 2000.

2. Burke W. Oral contraceptives and breast cancer: a note of caution for high-riskwomen. JAMA: the Journal of the American Medical Association 284:1837-1838, 11 Oct 2000.

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Reactions 21 Oct 2000 No. 8240114-9954/10/0824-0001/$14.95 Adis © 2010 Springer International Publishing AG. All rights reserved