Ovarian and endometrial cancer
Use of COCs helps protect users from two kinds of cancer—cancer of the ovaries and cancer of the lining of the uterus (endometrial cancer).
This protection continues for 15 or more years after stopping use.
Breast cancer
Research findings about COCs and breast cancer are difficult to interpret:
– Studies find that women who have used COCs more than 10 years ago face the same risk of breast cancer as similar women who have never used COCs.
In contrast, current users of COCs and women who have used COCs within the past 10 years are slightly more likely to be diagnosed with breast cancer.
– When a current or former COC user is diagnosed with breast cancer, the cancers are less advanced than cancers diagnosed in other women.
– It is unclear whether these findings are explained by earlier detection of existing breast cancers among COC users or by a biologic effect of COCs on breast cancer.
Cervical cancer
Cervical cancer is caused by certain types of human papillomavirus (HPV). HPV is a common sexually transmitted infection that usually clears on its own without treatment, but sometimes persists.
Use of COCs for 5 years or more appears to speed up the development of persistent HPV infection into cervical cancer.
The number of cervical cancers associated with COC use is thought to be very small.
If cervical screening is available, providers can advise COC users—and all other women—to be screened every 3 years (or as national guidelines recommend) to detect any precancerous changes on the cervix, which can be removed.
Factors known to increase cervical cancer risk include having many children and smoking.
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