Cancer and Birth Control Pills
An article in the prestigious medical journal The Lancet, November 10, 2007, Vol. 370: pp.1609-21, reports on a re-examination of cervical cancer data from 24 earlier worldwide studies. These studies were conducted to look at birth control pill use and cervical cancer. The study investigators felt it was important to re-evaluate this data as “the International Agency for Research on Cancer (IARC) has classified combined oral contraceptives as carcinogenic to humans on the basis of increased risk for cancer of the cervix.” (The Lancet, p.1609)
The 24 studies contained information from 26 countries worldwide and included 16,573 women with cervical cancer and 35,509 women without cervical cancer. The analysis of all of this data confirms that:
1. Current and recent use of combined oral contraceptives is associated with an increased risk of invasive cancer of the cervix;
2. The risk in current users of birth control pills increases with the length of time of use;
3. Use of birth control pills for 5 or more years doubles the risk of cervical cancer;
4. The increased risk of cervical cancer associated with birth control pill use diminishes with time since last use;
5. By 10 or more years since the last use of birth control pills, the risk of cervical cancer is similar to that in women who have never used birth control pills; and
6. There is a small increase in the risk of cervical cancer for women who use progesterone-only injectable contraceptives for 5 years or more. (The Lancet, p.1616)
To sum up the above findings, the studies showed that using birth control pills for 10 years, when a woman is around the ages of 20-30, increases the risk of getting cervical cancer by the age of 50 from 3.8 for every 1000 women to 4.5 per 1000 women. In less developed countries the risk went from 7.3 to 8.3 per 1000 women. (The Lancet, p. 1609)
Women have been concerned about the link between breast cancer and taking hormones. In April of 2007, NPR covered a story about a study published in The New England Journal of Medicine.
The study showed that a decrease in hormone use by women has led to a decline in breast cancer cases. Read more...
For more information on breast cancer and hormones, go to our web page on breast health.