Oral contraceptives and cancer.

The use of combined oral contraceptives has been shown in a number of studies to alter a women's risk of developing some kinds of cancer. Specifically, a 50% reduction in the risk of both ovarian and endometrial cancer has been demonstrated. This protective effect appears to persist for some time after oral contraceptives are stopped. Combined oral contraceptives do not appear to effect substantially the overall risk of developing breast cancer, although some data suggest that selected subgroups of women may be at a greater risk of developing breast cancer if oral contraceptives are used at specific times in a woman's reproductive life, especially if used for long periods of time. However, the data are not entirely consistent on this issue. The effect of oral contraceptives on the risk of developing cervical cancer is also not entirely clear, although the data available suggest a slightly increased risk of intraepithelial cervical cancer with prolonged use of oral contraceptives.