Also says that taking an oral contraceptive less than eight years wont boost cancer risk


Taking the contraceptive pill doesnt increase a womans chances of developing cancer and may even reduce the risk for most women, according to a recent study published on bmj.com.


There was, however, an increased risk for women who used it for more than eight years, the study found.


Since oral contraceptions introduction in the early 1960s, more than 300 million women are thought to have used it. Although several studies have looked at the overall balance of cancer deaths associated with oral contraceptives, none so far have examined the absolute risks or benefits.


Researchers from the University of Aberdeen, in Aberdeen, Scotland, analyzed data spanning a 36-year period from the Royal College of General Practitioners (RCGP) Oral Contraception Study, which began in 1968.


The study recruited 46,000 women, with an average age of 29. About half were using oral contraceptives; the other half had never taken them. Every six months, their doctors provided the study with information on the womens health. In addition, three quarters of the women were flagged at the NHS central registries so that the study group was notified of deaths and cancers.


Professor Philip Hannaford and colleagues used the data to calculate the risk of developing any type of cancer and the main gynecological cancers combined. They also considered the effects of variables such as age, smoking, and social class.


Given the length of the study, a sizable number of doctors werent able to provide updates throughout the entire study period.


So the researchers calculated the cancer risks using two sets of data. One set related to cancers reported while the women remained registered with their recruiting doctor and whose information was more detailed. The second data set was larger, including cancers documented by national health registries after women had left the care of participating doctors.


In both cases, there was no overall increased risk of cancer among pill users.


When the data set was used involving direct observation by participating doctors, women who had taken the pill at some time during their lives had a 3 percent reduced risk of developing any cancer. When the larger main data set was used, the reduction was 12 percent.


A 12 percent reduction equates to about one less case of cancer for every 2,200 women who have used the pill for a year and 3 percent equates to one less case of cancer for every 10,000 women. In the larger data set, women on the pill had statistically much lower rates of large bowel/rectal, uterine body, and ovarian cancer. The other data set also showed a reduced risk of uterine and ovarian cancer.


The researchers did sound a note of caution. When the women were examined by how long they had used the pill, women who used it for more than eight yearsless than a quarter of pill users in the studyhad a statistically significant increased risk of developing any cancer, in particular cervical and central nervous system cancer.


The same women, however, were at reduced risk of developing ovarian cancer. Evidence suggests that the protective effect of taking the pill lasts for at least 15 years after stopping.


The authors say that many women, especially those who used the first generation of oral contraceptives many years ago, are likely to find the results reassuring.Periods and new pillSeparately, an article focusing on the new birth control pill Lybrel, which is the first oral contraceptive designed to be taken 365 days a year with no pill-free intervals, notes that there are both risks and benefits to suppressing menstruation. The article appeared in the September issue of Harvard Womens Health Watch.


Women who use Lybrel dont have regular periods, although they may have some bleeding.


The idea of preventing periods isnt completely new. Conventional oral contraceptives also stop periods if they are taken continuously, and a clinician may suggest this approach to enable a woman to skip her period at an inconvenient time, such as during her honeymoon. The notion of suppressing periods over a longer term has become increasingly attractive, partly because this strategy has helped with treating endometriosis and managing the hormonal swings of perimenopause.


Theres some justification for reducing the number of periods or eliminating them altogether. For some women, eliminating periods can mean avoiding cramps, mood swings, headaches, and heavy bleeding that can cause anemia. On the other hand, many women are uncomfortable with the notion of not having periods.


One concern about Lybrel is that if it fails, a woman may not know she is pregnant.


The Harvard Womens Health Watch notes that there are no long-term safety data on Lybrel, but its risks are thought to be similar to conventional oral contraceptivesan increased incidence of blood clots, heart attacks, and stroke, especially in smokers.


On the plus side, birth control pills appear to lower the risk of ovarian and endometrial cancers; Lybrel might do the same. But the effects of taking Lybrel for more than a year are unknown. The use of continuous birth control has to be considered largely uncharted territory.