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that place them at increased risk of heart diseasedespite a low risk lifestyle. The UK has yet to promotea national strategy for cholesterol screening; potentialoptions include selective screening based on a positivefamily history, opportunistic screening guided by anassessment of all risk factors, and universal screeningof young men. Is there a convincing case for

including cholesterol measurement in child healthsurveillance?A valid screening programme should detect an

important disease about which there is adequateunderstanding of the natural history, and for whichthere is effective prevention or therapy. There is nodispute that coronary heart disease is important andthat it probably has its origins in childhood, if notearlier.4,5 Raised cholesterol is an established risk

factor; trials of serum cholesterol reduction in adultsshow a decrease in coronary heart disease incidenceand in mortality from this condition.6 Age-relatedpopulation data for blood lipid levels7,8 are availableand longitudinal studies are beginning to define thenature of tracking of high levels into adult life.3 It isclaimed that 25-50% of adult low-density-lipoprotein-cholesterol variability can be attributed tochildhood concentrations. A programme based on6500 3-18-year-olds living in suburban Ohio2 foundthat 20% had capillary cholesterol concentrationsabove 4-8 mmoll, a value previously suggested as theninetieth centile for this age group. Subsequentfasting blood lipid analysis in 500 high rankers showedthat 93% still had high cholesterol concentrations.9Others have shown substantial variability withinindividuals, and multiple measurements with reliabletechniques are essential before assigning a child to ahigh-risk category. Several studies report that onlyhalf the high rankers would have been detected ifscreening had been limited to children with a positivefamily history. 2,10 Before family history is dismissed asa guide to children who merit cholesterolmeasurement we need more information about the

phenotypic and genotypic classification of

hyperlipidaemia discovered by population screening.Are hypercholesterolaemic children with apparentlyhealthy parents really at risk, or is it more relevant toask whether either parent smokes? Family history willsurely become a more reliable guide as strategies forassessing risk factors and conducting cholesterol

screening in the adult population evolve.There is no justification for inadequately structured

screening generated merely by the availability ofequipment and divorced from the support of

diagnostic and counselling skills. There is also scantevidence that allocating children who do not have apositive family history to an apparent higher riskcategory serves as a stimulus to improved health-related lifestyle. Any benefit claimed has to be judgedagainst that which can be achieved by public healthstrategies supported by statutory measures. Allocatingill-defined risk to a child is a threat to the family, andmay well have deleterious effects on harmony and

health. Diabetic teenagers have already taught us thatemphasising potential health hazards does little to

generate compliance. Self-discipline and sustainedmotivation are fragile qualities in adolescence, and it isunlikely that knowledge of a raised cholesterolconcentration will be a reforming influence. In healthsystems that must decide priorities, risk factordetection and management has to be a staged process,with those at greater risk given preference.6 Resourcesare better directed at children in whom a careful

family history suggests a risk of familial

hypercholesterolaemia or allied disorders, and inwhom there is a clear case for long-term dietarysupervision and possible drug therapy. The challengeis to define risk status more precisely, possibly by useof apolipoprotein B measurement," and to developtreatment strategies that are effective and safe inyoung people.

1. Office of Population Censuses and Surveys. Deaths by cause: 1987registrations. OPCS Monitor, 1988 (Sept 17).

2. Garcia RE, Moodie DS. Routine cholesterol surveillance in childhood.Pediatrics 1989; 84: 751-55.

3. Lauer RM, Lee J, Clarke WR. Factors affecting the relationship betweenchildhood and adult cholesterol levels: the Muscatine study. Pediatrics1988; 82: 309-18.

4. Barker DJP, Winter PD, Osmond C, Margetts B, Simmonds SJ. Weightin infancy and death from ischaemic heart disease. Lancet 1989; ii:

577-80.5. Barker D. The intrauterine origins of cardiovascular and obstructive lung

disease in adult life. J R Coll Physicians Lond 1991; 25: 129-33.6. Lewis B, Rose G. Prevention of coronary heart disease: putting theory

into practice. J R Coil Physicians Lond 1991; 25: 21-26.7. Rifkind B, Sega P. Lipid Research Clinics Program reference values for

hyperlipidemia and hypolipidemia. JAMA 1983; 250: 1869-72.8. Srinivasan S, Frerichs R, Weber L, Berenson G. Serum lipoprotein

profile in children from a biracial community: the Bogalusa HeartStudy. Circulation 1976; 54: 309-18.

9. Garcia RE, Moodie DS. Lipoprotein profiles in hypercholesterolemicchildren. AM J Dis Child 1990; 145: 147-50.

10. Dennison BA, Kikuchi DA, Srinivasan SR, Webber LS, Berenson GS.Parental history of cardiovascular disease as an indication for screeningfor lipoprotein abnormalities in children. J Pediatr 1989; 115: 186-94.

11. Sniderman A, Silberberg J. Is it time to measure apolipoprotein B?Arteriosclerosis 1990; 10: 665-67.

Breast cancer screening in womenunder 50

Recent debate about the optimum treatment forbreast cancer1,2 must have alarmed many women who

previously had thought that early diagnosis andcurative resection were the twin planks on whicheffective management rested. Their fears will not havebeen allayed by a front page story in the Sunday Timesof June 2 under the headline "Breast scans boost riskof cancer death". The report described interviewswith Dr Cornelia Baines (Department of PreventiveMedicine and Biostatistics, University of Toronto,Canada) and Prof Anthony Miller (currently at theWorld Health Organisation, Geneva), the senior

investigators of the Canadian National Breast

Screening Study. These researchers found thatwomen aged 40-49 years who had undergonemammography and physical examination had a higherdeath rate from breast cancer than women who had

undergone only a single physical breast examination.

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In this age group, the Canadian study set out to find"what reduction in breast cancer mortality could beobserved with combined annual screening[mammography and physical examination of thebreasts] compared to normal community care [yearlyself-examination reminders] following a singlephysical examination of the breasts". 3,4 The studyincluded 50 000 volunteers and was conductedbetween 1980 and 1988. The study protocol and thereliability of the data have already been fiercelycriticised.5 In at least the first 2 years of the study, over50% of mammograms were inadequate; only in thelast 2 years of the trial was image quality technicallyacceptable in more than 70% of screenings. Modemradiographic equipment was not routinely available toparticipating centres, and the equipment used was notstandardised. In addition, there was no coordinatedtraining programme for either radiologists or

radiographers. These discrepancies led two externaladvisers to resign. Kopans,5 who is a co-author ofearlier reports of the Canadian study,4 wrote thatbecause of uncertainty as to whether disease severitywas equally distributed between the groups of women"the results of this trial will always be suspect". Thatthe Canadian study has no bearing on the UKscreening programme, which involves mammographyin women aged 50-64 years only and has a centralisedorganisation with recognised training courses andquality assurance standards, was not made clear in thenewspaper article.The latest Canadian results, which have not been

published, were discussed at the Second InternationalCambridge Conference on Breast Cancer Screening inApril. Concerns about group comparability because ofpoor randomisation seem to have been unfoundedsince there were equal numbers of non-breast-cancerdeaths (157) in the screened and control groups. The44 deaths from breast cancer in the screened group vs29 in the control group translates into a 52% increasein breast cancer mortality among those screened. Poorquality mammography may lead to a poor qualityscreening programme but this should not in itself leadto increases in mortality in the study group. Althoughthese results are the first to show a statisticallysignificant increase in breast cancer mortality in a

population who underwent screening mammography,other published studies have shown non-significanttrends in the same direction, ranging from 3 to 29%with 6-8 years of follow-up.&-9 The death rates in theCanadian study may fall with time since a longer periodof follow-up seems to diminish the adverse effect ofmammography in this age group (I. Andersson,Second International Cambridge Conference on

Breast Cancer Screening, April, 1991).10,llWhy does mortality increase during the initial

period of follow-up? One explanation may be thetype of treatment offered to women with

mammographically detected breast cancers-usuallya combination of surgery and radiotherapy. Thus,when many of these trials began in the early 1980s,

adjuvant systemic therapy was not given routinely.Systemic therapy soon after or coincident with

surgery for premenopausal women with breast cancermay be the important variable that is missing from thetreatment associated with these screening studies. It ispossible that systemic therapy is especially importantin the younger age group.The implications of these results remain uncertain.

There is no evidence to support introduction ofservice mammography for women under 50, and somemay argue that there should be a moratorium on all

mammography for symptom-free women in this agegroup outside randomised controlled trials.12 In the

UK, some private sector schemes are activelyrecruiting younger women into mammographyprogrammes. The Canadian data and the results of areview of all Swedish screening trials due to be

published at the end of this year will have a bearing ona new UK trial that aims to randomise individually200 000 women aged 40-41 years to assess the value ofyearly mammography on breast cancer mortality.One-third of women in the UK trial will be in the

study group while two-thirds will act as controls. 3-3deaths per 1000 women are expected during the10-year trial. The study group size is sufficient to givean 80% power of detecting a 20% reduction in

mortality over a 10-year period-to 2-6 per 1000women-at the 5% significance level. Recruitment atpilot centres in Guildford and Edinburgh has alreadybegun; it may be necessary to revise the protocol toinclude recommendations for treatment before

extending the trial to other centres.

1. Fentiman IS, Mansel RE. The axilla: not a no-go zone. Lancet 1991; 337:221-23.

2. Badwe RA, Gregory WM, Chauddry MA, et al. Timing of surgeryduring menstrual cycle and survival of premenopausal women withoperable breast cancer. Lancet 1991; 337: 1261-64.

3. Baines CJ. Evaluation of mammography and physical examination asindependent screening modalities in the Canadian National BreastScreening Study. In: Ziant G, ed. Practical modalities of an efficientscreening for breast cancer in the European community. Amsterdam:Elsevier, 1989: 3-9.

4. Baines CJ, Miller AB, Kopans DB, et al. Canadian National BreastScreening study: assessment of technical quality by external review.AJR 1990; 155: 743-47.

5. Kopans DB. The Canadian Screening Program: a different perspective.AJR 1990; 155: 748-49.

6. Shapiro S, Venet N, Strax P, Venet L, Roeser R. Ten to fourteen yeareffect of breast cancer screening on mortality. J Natl Cancer Inst 1982;69: 349-55.

7. Tabar L, Gad A, Homberg LH, et al. Reduction in mortality from breastcancer after mass screening with mammography. Lancet 1985; i:

829-32.

8. Verbeek ALM, Hendriks JHCL, Holland R, Mravunac M, Sturmans F.Mammographic screening and breast cancer mortality: age-specificeffects in Nijmegen project 1975-82. Lancet 1985; i: 865-66.

9. Andersson I, Aspegren K, Janzon L, et al. Mammographic screening andmortality from breast cancer: the Malmo mammographic screeningtrial. Br Med J 1988; 297: 943-48.

10. Shapiro S, Venet W, Strax P, Venet L. Periodic screening for breastcancer: the Health Insurance Plan Project and its sequelae. Baltimore:Johns Hopkins University Press, 1988: 1963-86.

11. Tabar L, Fagerberg F, Duffy SW, Day NE. The Swedish Two CountiesTrial of Mammographic Screening for Breast Cancer: recent resultsand calculation of benefit. J Epidemiol Community Health 1989; 43:107-14.

12. Royal College of Radiologists and National Radiological ProtectionBoard. Patient dose reduction in diagnostic radiology. Documents ofthe NRPB, vol 1. London: HM Stationery Office, 1990.