JNCI：母乳喂养或可有效降低女性个体乳腺癌的复发风险

  近日，一篇刊登于国际杂志Journal of the National Cancer Institute上的研究论文中，来自美国凯萨医疗研究部门（Kaiser Permanente Division of Research）的研究人员通过研究表明，进行母乳喂养可以使得患乳腺癌的女性总的癌症复发风险降低30%，而研究者指出，母乳喂养的保护效应对于具有特殊遗传亚型的肿瘤较为明显，包括最为常见的乳腺癌。
  文章中，研究者对1636名乳腺癌患者进行了调查问卷，其中内容包括患者的母乳喂养史；研究者Marilyn L. Kwan说道，这项研究中我们首次检测了母乳喂养在癌症复发中所扮演的角色，结果发现，母乳喂养对于细胞腔A亚型乳腺癌的帮助具有预期的效果，而对于其它乳腺癌亚型却没有明显的关联，细胞腔A肿瘤包括雌激素受体阳性（ER+）乳腺肿瘤，其是最为常见的乳腺癌，这些肿瘤一般不易于转移，而且常可以利用激素疗法来治疗，比如他莫昔芬等，效果比较显著。
  母乳喂养除了可以降低乳腺癌的复发率外，而且还可以使得女性个体因乳腺癌死亡的风险降低28%；目前有很多可能性的解释来帮助解析为何母乳喂养和乳腺癌个体较好的预后直接相关，母乳喂养的个体更易于患细胞腔A亚型乳腺癌，但其往往具有低侵袭性而且母乳喂养可以建立一种环境来使得肿瘤对抗雌激素疗法的反应更加明显。
  目前研究者并不清楚为何母乳喂养的女性会产生较低侵袭性的肿瘤，研究者Bette J. Caan表示，母乳喂养可以增加乳腺中导管细胞的成熟，从而使其对致癌物更加敏感或者促进其对致癌物的分泌，最终使得肿瘤生长速度降低；目前科学家们推荐女性最好利用母乳喂养来进行婴儿的哺育，而且相关研究结果也证实了母乳喂养的好处，实际上这种保护作用对于母乳喂养6个月及以上的女性更加强烈。（转化医学网360zhyx.com）
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转化医学网推荐的原文摘要：

Breastfeeding, PAM50 Tumor Subtype, and Breast Cancer Prognosis and Survival
J Natl Cancer Inst   doi: 10.1093/jnci/djv087
Marilyn L. Kwan, Philip S. Bernard, Candyce H. Kroenke, Rachel E. Factor, Laurel A. Habel, Erin K. Weltzien, Adrienne Castillo, Erica P. Gunderson, Kaylynn S. Maxfield, Inge J. Stijleman, Bryan M. Langholz, Charles P. Quesenberry Jr, Lawrence H. Kushi, Carol Sweeney and Bette J. Caan
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% confidence intervals (CIs) between breastfeeding and tumor subtype. Cox regression was used to estimate hazard ratios (HRs) for breast cancer recurrence or death. Statistical significance 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 trend = .01). Similar associations were observed for breast cancer death. Among women with luminal A subtype, ever 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 significant 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.