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Oral contraceptives seem to increase the risk of breast cancer. While the Pill's composition and patterns of use have evolved, €more recent formulations have received relatively little scrutiny€, a recent paper remarks.

The authors examined 1,102 women aged 20-49 years with invasive breast cancer and 21,952 matched controls. Overall, women who used oral contraceptives within the previous year were 50 per cent more likely to develop breast cancer compared to never or former users. The association was stronger for oestrogen receptor-positive (70 per cent increased risk) than oestrogen receptor-negative (20 per cent) breast cancer. However, this difference did not reach statistical significance.

The overall risk of breast cancer and oestrogen receptorpositive malignancies increased significantly with the number of pills dispensed during the past year.

Using oral contraceptives during the past year that included high-dose oestrogen (odds ratio [OR] 2.7), ethynodiol diacetate (OR 2.6) or triphasic dosing with an average of 0.75mg of norethindrone (OR 3.1) were associated with €particularly elevated€ breast cancer risks.

The latter was the only oral contraceptive that showed a significantly different risk of breast cancer compared to the other formulations. However, some formulations €“ such as low-dose oestrogen and norethindrone 0.50mg €“ did not significantly increase breast cancer risk compared to never or former use.

€Our results suggest that use of contemporary oral contraceptives in the past year is associated with an increased breast cancer risk relative to never or former oral contraceptive use, and that this risk may vary by oral contraceptive formulation,€ said lead author Elisabeth Beaber, a staff scientist at the public health sciences division of the Fred Hutchinson cancer research center in Seattle.

€Our results require confirmation and should be interpreted cautiously. Breast cancer is rare among young women and there are numerous established health benefits associated with oral contraceptive use that must be considered. In addition, prior studies suggest that the increased risk associated with recent oral contraceptive use declines after stopping oral contraceptives.€