Breast cancer treatment patterns by age and time since last pregnancy in the Carolina Breast Cancer Study Phase III.

PURPOSE: To describe breast cancer treatment patterns among premenopausal women by age and time since last pregnancy. METHODS: Data were analyzed from 1179 women diagnosed with premenopausal breast cancer in the Carolina Breast Cancer Study. Of these, 160 had a recent pregnancy (within 5 years of cancer diagnosis). Relative frequency differences (RFDs) and 95% confidence intervals (CIs) were used to compare cancer stage, treatment modality received, treatment initiation delay (> 30 days), and prolonged treatment duration (> 2 to > 8 months depending on the treatment received) by age and recency of pregnancy. RESULTS: Recently postpartum women were significantly more likely to have stage III disease [RFD (95% CI) 12.2% (3.6%, 20.8%)] and to receive more aggressive treatment compared to nulliparous women. After adjustment for age, race and standard clinical tumor characteristics, recently postpartum women were significantly less likely to have delayed treatment initiation [RFD (95% CI) - 11.2% (- 21.4%, - 1.0%)] and prolonged treatment duration [RFD (95% CI) - 17.5% (- 28.0%, - 7.1%)] and were more likely to have mastectomy [RFD (95% CI) 14.9% (4.8%, 25.0%)] compared to nulliparous. Similarly, younger women (< 40 years of age) were significantly less likely to experience prolonged treatment duration [RFD (95% CI) - 5.6% (- 11.1%, - 0.0%)] and more likely to undergo mastectomy [RFD (95% CI) 10.6% (5.2%, 16.0%)] compared to the study population as a whole. CONCLUSION: These results suggest that recently postpartum and younger women often received prompt and aggressive breast cancer treatment. Higher mortality and recurrence among recently pregnant women are unlikely to be related to undertreatment.