Current status and challenges of breast cancer prevention~DNA methylation would lead to groundbreaking progress in breast cancer prevention~

The number of breast cancer patients is increasing worldwide. Furthermore, breast cancer often develops in young people, even those only in their 30s, who play a central role in their families and society. Results from many cohort studies suggest that dietary factors, alcohol consumption, lack of physical activity, obesity, nulliparity, breastfeeding, oral contraceptive use, fertility treatment and hormone replacement therapy are risk factors for breast cancer. However, the effects of lifestyle habits on the human body are complexly intertwined with various factors, and the effects vary from person to person depending on their constitution, etc., so there is no basis for this. Therefore, primary prevention of breast cancer is still not being implemented appropriately and efficiently. Furthermore, advances in genomic technology make it possible to assess the risk of developing breast cancer in some individuals. As a result, the establishment of breast cancer prevention methods has become a health priority for high-risk individuals. Drugs such as tamoxifen and raloxifene are known to prevent the development of breast cancer, based on the results of multiple randomized controlled trials, but there are concerns regarding the side effects of these powerful agents. In addition, several clinical studies have shown that prophylactic mastectomy for women who have BRCA mutations or who are identified as being at high risk reduces the incidence of breast cancer development. However, many issues, such as changes in long-term quality of life after preventive surgery, the optimal timing of surgery and the identification of women who are at high risk but will not develop breast cancer, remain uncertain. In other words, although many researchers have focused on chemoprevention and surgical prevention and clear preventive effects of these strategies have been confirmed, it cannot be said that they are widely accepted. Therefore, the current evidence for chemoprevention and surgical prevention, as well as highlights of several interesting lines of research currently underway, are summarized in this article.