Use of Pill over short term may reduce cancer risk
Irish Examiner 13/09/2007
by Sam Reeves
TAKING the contraceptive pill over a short period may reduce a woman's chances of getting cancer — but taking it for too long may increase the risk, scientists said yesterday.
Women who take the pill can have up to a 12% lower risk of developing the disease, according to a study published in the British Medical Journal.
But the same research also showed women who used the pill for more than eight years — a quarter of those in the study — had a significantly higher risk of developing cancer.
Scientists at the University of Aberdeen found those who took the contraceptive for shorter periods suffered from significantly lower rates of bowel and rectal cancer, uterine cancer and ovarian cancer.
And up to 29% had a reduced risk of developing one of the main gynaecological cancers.
But those who took the pill for more than eight years had an increased risk of developing all forms of cancer, particularly cervical and central nervous system cancer.
Some previous studies have suggested earlier forms of the pill may have increased the risk of developing the disease.
The research is one of the largest detailed studies of the pill in the world.
Scientists recruited 46,000 women in 1968 to take part. Half were already using oral contraceptives, and the other half had never taken them.
Researchers at the University of Aberdeen recently analysed the data, which spans a 36-year period, to come up with the findings.
The cancer risks were calculated using two sets of data. The first related to cancers reported while the women were registered with the GP who first recruited them, and whose information was more detailed.
The second main study was larger and included cancers noted by central NHS registries.
This was necessary because many women moved from the GPs who originally signed them up to the study, and so had to be linked to the central registries.
In the smaller study — using the data from GPs — there was a 3% reduced risk of developing any cancer.
This is much lower than in the larger study, where the reduction was 12%.
But the 3% result still represented one fewer case of cancer for every 10,000 women, researchers noted.