Cramer Daniel W
Department of Obstetrics, Gynecology and Reproductive Biology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.
Front Oncol. 2023 Oct 6;13:1240309. doi: 10.3389/fonc.2023.1240309. eCollection 2023.
Estrous cycles are recurring changes in therian mammals induced by estrogen, progesterone, and other hormones culminating in endometrial proliferation, ovulation, and implantation if fertilization occurred. In women, the estrous cycle is the menstrual cycle; but, unlike most mammals, the end of an infertile cycle is marked by endometrial sloughing and the start of another without an anestrous phase. Women stop cycling at menopause, while in most mammals, cycles continue until death. Epidemiologic studies identified menarche, menopause, births, lactation, and oral contraceptive (OC) use as key risk factors for ovarian, breast, and endometrial cancers. A composite variable was created to estimate the number of cycles not interrupted by events that stop ovulation. Captured by the phrase "incessant ovulation", repetitive cycles were first postulated to affect ovarian cancer risk and later extended to breast and endometrial cancers. These associations could be explained by cumulative effects of repetitive tissue changes within reproductive organs, immune consequences of repetitive ovulation through the glycoprotein mucin 1, and residual effects of past ovulations that enhance ovarian production of testosterone. The latter two pathways could affect the risk for cancers in other organs not considered "reproductive".
发情周期是有袋类哺乳动物由雌激素、孕激素和其他激素引起的周期性变化，如果发生受精，最终会导致子宫内膜增生、排卵和着床。在女性中，发情周期即月经周期；但是，与大多数哺乳动物不同，未受孕周期的结束以子宫内膜脱落为标志，且新周期开始时没有发情间期。女性在绝经时停止月经周期，而在大多数哺乳动物中，周期会持续到死亡。流行病学研究确定初潮、绝经、生育、哺乳和口服避孕药的使用是卵巢癌、乳腺癌和子宫内膜癌的关键危险因素。创建了一个综合变量来估计未被停止排卵的事件打断的周期数。用“持续排卵”这一表述来概括，重复周期最初被认为会影响卵巢癌风险，后来又扩展到乳腺癌和子宫内膜癌。这些关联可以通过生殖器官内重复组织变化的累积效应、通过糖蛋白粘蛋白1重复排卵的免疫后果以及过去排卵的残留效应来解释，这些残留效应会增强卵巢产生睾酮的能力。后两种途径可能会影响其他未被视为“生殖”器官的癌症风险。
