Although the results of existing studies are often contradictory, it is clear that oral contraceptives increase the risk of breast and cervical cancers and decrease the risk of endometrial and ovarian cancers in women. Increased breast cancer risk Compared to women who never use birth control pills, the use of birth control pills mildly increases the risk of breast cancer, and it is not yet possible to determine whether this is related to estrogen or progestin. Some studies have suggested an association with high doses of estrogen, but there was also an increased incidence of breast cancer in women using progestin-only contraception in the study. Other studies have shown that the increased risk of breast cancer disappears if the oral contraceptive pill is discontinued for ≥10 years. The following methods can help reduce the risk of breast cancer: minimizing the duration of use of birth control pills; using multiple methods of birth control, such as hormone-free intrauterine devices (IUDs), which do not increase the risk of breast cancer and may also reduce the risk of cervical and endometrial cancer. Increased risk of cervical cancer Use of birth control pills for ≥5 years is more likely to result in cervical cancer, and the risk increases the longer you use them, and decreases over time after you stop using them. However, in the real world most cervical cancers are caused by persistent infection with human papillomavirus (HPV), so HPV testing and Pap tests are routinely included in women’s health exams. The following methods can help reduce the risk of cervical cancer: regular HPV testing; alternative forms of birth control such as IUDs. Reducing the risk of endometrial cancer The estrogen and progestin in birth control pills can reduce the risk of endometrial cancer, and the longer they are used, the lower the risk, even after stopping them for up to 10 years; and IUDs can also help reduce the risk of endometrial cancer. Reducing the risk of ovarian cancer Combination estrogen and progestin birth control pills can reduce the risk of ovarian cancer, with benefits occurring after 3-6 months of use, and the longer the use, the lower the risk of ovarian cancer. Depo-Provera, which contains megestrol, also reduces the risk of ovarian cancer, with a greater benefit for ≥3 years of use. For women who do not want to have more children and do not want to use birth control pills, tubal resection or ligation is available, and this form of contraception can also help reduce the risk of ovarian cancer. The use of the pill reduces the risk of colorectal cancer as well as reproductive cancers, but more research is needed to support this conclusion. Conclusion When choosing a form of contraception, women should communicate fully with their physicians and try to take all influencing factors into account. Oral contraceptives have therapeutic effects for many conditions, such as endometriosis, and of course contraception itself has many effects, some of which are beneficial for some but may be harmful for others, so it is important to consider all factors as well as family history of cancer when choosing a form of contraception.