Oral contraceptive may boost breast cancer risk

Oral contraception is readily available and highly effective at preventing pregnancy.  UK researchers have now developed a type of morning after pill that prevents pregnancy within five days after sexual intercourse.

But there is some concern about the safety of the birth control method because the contraceptive is made of hormones which have been suspected to raise breast cancer risk for a long time.

A study published Jan 15 in the Cancer Research has found oral contraceptive may at least boost triple-negative (ER(-)/PR(-)/HER2(-) breast cancer.

Ma H and colleagues of the City of Hope Medical Center in Duarte, California analysed data from 1,197 population-based cases and 2,015 controls and evaluated the associations between oral contraceptive use and invasive breast cancer subtypes.

The researchers found women aged 45 to 64 years who started taking oral contraceptives at 18 were at 2.9 fold increased risk of triple-negative tumors. But no association was found for any other type of breast cancer.

They also found the number of births and age at first full term pregnancy was associated with the risk of (ER(+) or PR(+), HER2(-)) breast cancer.  Long duration of breastfeeding reduced the risk of this type of tumor and triple negative tumors.

It has been known that full-term pregnancies at young ages reduce breast cancer risk.  Early voluntary termination of pregnancy results in high risk for the disease.

Breast cancer is diagnosed in 170,000 women each year in the United States and the disease kills about 50,000 annually in the country, according to the National Cancer Institute.

By David Liu