Reproductive history and breast cancer survival: a prospective patient cohort study in Japan

• Published in: Breast cancer (Tokyo, Japan) Japan), 2019-11, Vol.26 (6), p.687-702
• Main Authors: Minami, Yuko, Nishino, Yoshikazu, Kawai, Masaaki, Tada, Hiroshi, Kanemura, Seiki, Miyashita, Minoru, Ishida, Takanori, Kakugawa, Yoichiro
• Format: Article
• Language: English
• Subjects: Adult; Age Factors; Aged; Aged, 80 and over; Analysis; Breast cancer; Breast Neoplasms - mortality; Breast Neoplasms - pathology; Cancer; Cancer patients; Cancer Research; Cancer Survivors; Development and progression; Disease Progression; Estrogen; Female; Follow-Up Studies; Humans; Japan; Kaplan-Meier Estimate; Medicine; Medicine & Public Health; Menarche; Menopause; Middle Aged; Oncology; Oncology, Experimental; Original Article; Parity; Patient outcomes; Pregnancy; Progesterone; Proportional Hazards Models; Prospective Studies; Receptors, Estrogen - metabolism; Receptors, Progesterone - metabolism; Reproductive History; Risk Factors; Surgery; Surgical Oncology; Survival Rate
• ISSN: 1340-6868; 1880-4233
• DOI: 10.1007/s12282-019-00972-5

Background Reproductive factors may influence breast cancer progression and patient survival; however, evidence has been limited. Methods The associations of reproductive factors with tumor characteristics and patient survival were analyzed among 1468 breast cancer patients diagnosed during 1997–2013 at a single institute in Japan. The patients were followed until 2016. During a median follow-up period of 8.6 years, 272 all-cause and 199 breast cancer deaths were documented. Results In case–case comparisons, later age at menarche was inversely associated with advanced tumors. Nulliparous patients tended to have receptor-positive [estrogen receptor (ER)+ or progesterone receptor (PR)+] tumors. Conversely, the Cox proportional-hazards model including adjustment for tumor characteristics revealed U-shaped relationship between parity number and the risk of all-cause death among the patients overall [hazard ratio (HR) = 2.10 for nulliparous, 1.28 for 2, and 1.50 for ≥ 3 vs. one child]. According to hormone receptor, later age at menarche and later age at last birth were positively associated with the risk of all-cause death among patients with ER– and PR– cancer (menarche, HR = 2.18 for ≥ 15 vs. ≤ 12 years, p trend  = 0.03; last birth, HR = 3.10 for ≥ 35 vs. ≤ 29 years, p trend  = 0.01). A shorter time since last birth was associated with the risk of death among receptor-positive patients (HR = 5.72 for ≤ 4 vs. ≥ 10 years, p trend  = 0.004). Conclusion The results indicate that the timing of menarche and parity have significant effects on patient survival, providing clues for understanding the association between women’s life course and breast cancer outcome.