Risk of breast cancer in women exposed to diethylstilbestrol in utero: preliminary results (United States)Palmer JR, Hatch EE, Rosenberg CL, Hartge P, Kaufman RH, Titus-Ernstoff L, Noller KL, Herbst AL, Rao RS, Troisi R, Colton T, Hoover RN. Cancer Causes Control 2002;13:753-8.]
The question of whether daughters of women who took DES while pregnant with them will have a greater chance of getting breast cancer has been of great interest to both the DES population and researchers. Questionnaire data collected in 1994 and 1997 from participants in the combined follow-up study were used to investigate this question. 4821 exposed and 2095 unexposed women completed one or both of the follow-up questionnaires, answering questions on reproductive factors, health habits, and disease outcomes. Reports of breast cancer were confirmed by checking medical records or death certificates. There were 43 cases of breast cancer among the DES-exposed and 15 among the unexposed women.
Overall, exposed daughters did not have a statistically significant increase in the risk of breast cancer. Although the relative risk was 1.4, this elevation could have been a chance finding due to the small number of breast cancer cases. However, among the subgroup of women aged 40 and older, those exposed to DES were estimated to have 2.5 times the risk of breast cancer, and this result was statistically significant. Follow-up in the study has continued, and a new analysis that includes additional cases diagnosed since 1997 has begun. The new analysis will likely provide more definitive results.