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- Title
Breastfeeding, PAM50 Tumor Subtype, and Breast Cancer Prognosis and Survival.
- Authors
Kwan, Marilyn L.; Bernard, Philip S.; Kroenke, Candyce H.; Factor, Rachel E.; Habel, Laurel A.; Weltzien, Erin K.; Castillo, Adrienne; Gunderson, Erica P.; Maxield, Kaylynn S.; Stijleman, Inge J.; Langholz, Bryan M.; Quesenberry Jr, Charles P.; Kushi, Lawrence H.; Sweeney, Carol; Caan, Bette J.
- Abstract
Background: Breastfeeding is associated with decreased breast cancer risk, yet associations with prognosis and survival by tumor subtype are largely unknown. Methods: We conducted a cohort study of 1636 women from two prospective breast cancer cohorts. Intrinsic tumor subtype (luminal A, luminal B, human epidermal growth factor receptor 2 [HER2]-enriched, basal-like) was determined by the PAM50 gene expression assay. Breastfeeding history was obtained from participant questionnaires. Questionnaires and medical record reviews documented 383 recurrences and 290 breast cancer deaths during a median follow-up of nine years. Multinomial logistic regression was used to estimate odds ratios (ORs) and 95% conidence intervals (CIs) between breastfeeding and tumor subtype. Cox regression was used to estimate hazard ratios (HRs) for breast cancer recurrence or death. Statistical signiicance tests were two-sided. Results: Breast cancer patients with basal-like tumors were less likely to have previously breastfed than those with luminal A tumors (OR = 0.56, 95% CI = 0.39 to 0.80). Among all patients, ever breastfeeding was associated with decreased risk of recurrence (HR = 0.70, 95% CI = 0.53 to 0.93), especially breastfeeding for six months or more (HR = 0.63, 95% CI = 0.46 to 0.87, P = .01). Similar associations were observed for breast cancer death. Among women with luminal A subtype, ever trend breastfeeding was associated with decreased risks of recurrence (HR = 0.52, 95% CI = 0.31 to 0.89) and breast cancer death (HR = 0.52, 95% CI = 0.29 to 0.93), yet no statistically signiicant associations were observed among the other subtypes. Effects appeared to be limited to tumors with lower expression of proliferation genes. Conclusions: History of breastfeeding might affect prognosis and survival by establishing a luminal tumor environment with lower proliferative activity.
- Subjects
BREASTFEEDING; BREAST cancer prognosis; CANCER relapse; GENE expression; LOGISTIC regression analysis; CANCER risk factors
- Publication
JNCI: Journal of the National Cancer Institute, 2015, Vol 107, Issue 7, p1
- ISSN
0027-8874
- Publication type
Article
- DOI
10.1093/jnci/djv087