Risk of recurrence and death following breast cancer: influence of pregnancy and hormone replacement therapy
Velentgas, Priscilla T
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Women diagnosed with breast cancer while still in their reproductive years face special concerns regarding future childbearing following initial cancer treatment. Previous epidemiologic studies have not identified an adverse effect of pregnancy after breast cancer on survival, but have been unable to rule out bias as an explanation for their findings. Use of hormone replacement therapy (HRT) might provide relief of menopausal symptoms for women who undergo early menopause following breast cancer treatment, were it not for concerns about an adverse impact on prognosis. Little scientific evidence exists to determine whether use of HRT after breast cancer affects prognosis. This study of women diagnosed with primary invasive breast cancer before age 45 from 1983 to 1992 examined the influence of subsequent pregnancy or HRT use on risk of recurrence and death from breast cancer. Information on pregnancies and HRT use were obtained from questionnaires or telephone interviews completed by subjects or proxy respondents for deceased subjects. Overall response to the survey was 73%.Subsequent pregnancies were reported for 21% of women diagnosed before age 35, who had not undergone menopause or any surgical sterilization, compared with 1.4% of women diagnosed after age 35. There was no overall association between pregnancy following breast cancer and risk of recurrence or mortality. The adjusted relative risk for the association of subsequent pregnancy with recurrence was 1.0 (95% CI 0.3-2.9); the association with mortality was 0.9 (95% CI 0.2-4.2).Nine percent of subjects reported use of HRT after breast cancer diagnosis. The adjusted relative risk of recurrence associated with any subsequent HRT use was 1.5 (95% CI 0.7-3.0), and the adjusted association of subsequent HRT use with mortality was 3.9 (95% CI 1.6-9.6). The results suggest that HRT use after breast cancer may be associated with an increased risk of mortality of threefold or more. However, further evidence that this finding cannot be explained by overreporting of HRT use by proxies is being sought. Further studies of this question with accurate, prospective ascertainment of HRT use after breast cancer and recurrences are needed.
- Epidemiology