Contraceptive pills may cut cancer risk for women

14 September, 2007

The contraceptive pill, often described as one of the most significant medical advances of the 20th century, does not enhance a woman’s risk of
developing cancer and, for a majority of women, it might even reduce that hazard.

This is the finding of a long-term study based on 46,000 British women who had an average age of 29 when the survey began in 1968.

Roughly half of the women were taking oral contraceptives, and the other half had never taken it.

Over the 36 years of the study, which appears in the British Medical Journal, many women dropped out of the study, so the investigators used two additional datasets to get a comparative view of the cancer risk.

The authors, from the University of Aberdeen, say that they found no overall increased risk of cancer among users of contraceptive pills. Instead, there was a reduced risk of 3% to 12% depending on which data batch was examined.

However, they found that, among women who had used contraceptive pills for over eight years – accounting for roughly a quarter of the Pill users – there was a statistically significant, increased risk of cancer of the cervix and central nervous system. But, the same women benefited from a reduced risk of developing ovarian cancer.

The study paper claims that “oral contraception was not associated with an overall increased risk of cancer; indeed it may even produce a net public
health gain.”

In 2005, a study of women conducted in Australia, the United States and Canada had found that young women with a genetic mutation placing them at high risk of breast cancer were substantially able to reduce their risk of developing the disease if they took oral contraceptives.

The contraceptive pill – which is inextricably connected to the swinging 60s, free love, and women’s liberation – is a combination of the hormones estrogen and progestin. It was developed in the United States in the 1950s by the American biologist Dr Gregory Pincus.

The Pill was approved for release in 1960. The take-up was quick – within two years, it was being used by 1.2 million women in the United States.

It was introduced in the United Kingdom in 1961 for married women only (this lasted until 1967), and is at present taken by 3.5 million women in Britain between the ages of 16 and 49.

The Pill, which comes in 32 different forms, is estimated to be taken worldwide by around 100 million women.

The Pill has been associated with health scares from the beginning, with reports in the US shortly after it was launched linking its use with blood clots, strokes, heart attacks, and diabetes.

But the number of women taking it continued to rise, even after reports in the 1970s showed that smoking and the Pill together increased the risk of blood clots. The number of users began to dip in the early 1980s owing to scares about its safety, as research suggested possible links between Pill use and breast cancer, strokes, heart attacks, and blood clots.

One study showed a 125% increase in the risk of breast cancer for women who used hormonal contraceptives for four years or more before having a full-term pregnancy, and a series of studies in the 1990s appeared to confirm the risk.

Some of the concerns were linked to hormone levels in the Pill, which have now been lowered.

A health scare in the United Kingdom in 1995 over thrombosis caused a drop in the Pill usage, and an increase in pregnancies and abortions. However, in 2000, a report in the British Medical Journal said the scare was unfounded.

On the positive side, the Pill has been shown to protect against cancer of the ovaries and the womb lining, and against pelvic inflammatory disease, a
major cause of infertility in women.

It can make periods more regular, but is not recommended for women over 35 who smoke heavily, the obese, or those with high blood pressure, a history of heart disease, blood clots or other specific illnesses such as breast cancer.