Impact of Cumulative Exposure to Circulating Ovarian Sex Hormones on Increasing the Risk of Hormone Receptor-Positive Breast Cancer

Abstract

There were 2.3 million new cases of breast cancer registered in 2020, establishing it as the world’s leading cancer. The regular exposure of breast cells to circulating ovarian sex hormones may contribute to cancer growth at all stages. A literature review was performed by downloading research articles from PubMed Central, with keywords such as breast cancer, hormone exposure in breast cancer, estrogen/progesterone exposure in breast cancer, and breast cancer risk factors. Since breast cancer is a hormone-related disease, several factors that influence hormonal conditions or are indicators of alterations in hormonal conditions have been linked with the risk for breast cancer. Likewise, an elevated risk for breast cancer has been related to reproductive history and exogenous estrogen exposure because they may amplify lifetime estrogen exposure. All these factors address the total cumulative exposure to circulating ovarian sex hormones that a female is vulnerable to in her lifetime. A healthy lifestyle, a more extended breastfeeding period, and regular physical activity may help lower one’s risk. This review summarizes the factors that increase the risk of estrogen/progesterone (hormone receptor) receptor-positive breast cancer due to overall cumulative estrogen exposure, with an understanding of estrogen biosynthesis mechanisms and estrogen receptor signaling.