Breast Cancer Outcomes After Diagnosis of Hormone-positive Breast Cancer and Subsequent Pregnancy in the Tamoxifen Era

Pregnancy after the diagnosis of breast cancer is an important survivorship issue. We conducted a retrospective analysis that included 32 premenopausal women with a diagnosis of estrogen receptor-positive breast cancer and subsequent pregnancy and an age- and stage-matched control cohort without subsequent pregnancy. The results of the present study did not demonstrate poorer disease-free survival in women who became pregnant within 5 years after their cancer diagnosis. Background Counseling patients regarding the risk of future pregnancy on hormone receptor-positive breast cancer outcomes is difficult because of the minimal data and understanding of pregnancy on the breast environment. Patients and Methods The present retrospective analysis included 32 premenopausal women with a diagnosis of estrogen receptor-positive breast cancer from 2000 to 2010 and subsequent pregnancy within 5 years. The control cohort included 29 women matched for age and stage of breast cancer who had not become pregnant. Results No statistically significant difference was found in age, diagnosis, stage, grade, or HER2 status between the 2 groups. Of the 32 women in the pregnancy cohort and 29 women in the control cohort, 19 (63%) and 23 (82%) had received endocrine therapy (P = .25). The mean length of endocrine therapy was 42.3 months (range, 0-120 months) in the control cohort and 20.9 months (range, 0-72 months) in the pregnancy cohort (P = .008). Four women (14%) in the control cohort experienced breast cancer recurrence compared with 8 women (26%) in the pregnancy cohort (P = .34). The 5-year disease-free survival rate was 92% (95% confidence interval, 81%-100%) in the control cohort compared with 84% (95% CI, 72%-97%) in the pregnancy cohort. The difference was not statistically significant (P = .69). Conclusion The results of the present study did not demonstrate poorer disease-free survival for premenopausal women with estrogen receptor-positive breast cancer who became pregnant within 5 years of diagnosis. Our study is unique because all included patients had estrogen receptor-positive disease and were offered adjuvant hormonal therapy. Further prospective investigation will be beneficial to patients and physicians as they discuss pregnancy as a key survivorship issue.