Contraceptive Pills Don’t Increase Cancer Risk
September 24, 2007
By: Beth Walsh for Uterus1
Contraceptive pills do not increase the overall risk of cancer and may even reduce some risks, according to a large British cohort study published online in the British Medical Journal. Women who used oral contraceptives for more than eight years, however, had an increased risk for cervical, pituitary, and central nervous system malignancies.
|How to Take the Pill Correctly:|
Start the first pack of pills within seven days of starting your menstrual cycle or at any other time your provider is reasonably sure that you are not pregnant. If you do not start your pills within seven days of starting your period, you will also need a back-up method of birth control for the first seven days you actually take the pill. Condoms and abstinence are methods that can protect against pregnancy during the first week of use.
If you miss one active pill, take that pill as soon as you remember, then continue taking your pills as usual. The active pills are the 21 pills that contain the birth control hormones. The inactive pills are the seven pills that do not contain hormones. The seven inactive pills, found only in 28-day packs, often contain iron for your blood. However, missing an inactive pill does not increase your risk of pregnancy.
If you miss two or more active pills in a row, continue taking the remaining pills in the current pack, one each day, until the pack is empty. Use another back-up method of contraception until you have taken active pills again for seven days in a row. These may be from the next pack.
More than 100 million women around the world take “the pill” to prevent pregnancy. Pills containing a combination of the hormones estrogen and progestin have an annual failure rate of less than 1 percent if taken exactly as directed, which is one pill each and every day without interruption. However, typical failure rates among pill users are as high as 12 to 20 percent in some surveys.
The four most common pill-taking errors are: Starting a pack late, without using a back-up contraceptive method;
Taking the pills in the wrong order, out of sequence;
Interrupting use for any reason; and
Not using additional, back-up contraception when two or more pills are missed.
Although previous research has suggested increased risks for breast, cervical, and liver cancer, two cohort studies examined the overall risk of death from cancer among women who have ever used oral contraception and never used it. Neither cohort study found significant differences between the two groups.
The current findings come from standardized data from the Royal College of General Practitioners' oral contraception study, which began in 1968. The information included cancers, periods of observation, information about type and duration of oral contraceptives used, and hormone replacement.
The researchers calculated adjusted relative risks between “never-users” and “ever-users” of oral contraceptives for different types of cancer, gynecological cancers combined, and any cancer. Standardization variables were age, smoking, parity, social class, and (for the general practitioner-observation dataset) hormone replacement therapy.
When compared with never-users, ever-users had statistically significantly lower rates of colorectal, uterine body and ovarian cancers, tumors of unknown site, and other malignancies, as well as main gynecological cancers combined and any cancer. Increasing duration of oral contraceptive use produced statistically significant trends for a decreasing risk of uterine and ovarian malignancies but an increasing risk of cervical, central nervous system, or pituitary cancer.
Most of the agents used in the study were combined oral contraceptives containing 50 µg of estrogen. But, because most women did not stay with one estrogen dose, the researchers said it was impossible to examine cancer risk by hormonal content of the pills used.
Researchers say these results suggest that, at least in this relatively healthy cohort, the benefits associated with oral contraception outweigh the risks. Further work, they concluded, is needed to quantify the risk-benefit balance.
Last updated: 24-Sep-07