Gynecologic Cancer: What Every Woman Should Know
Women’s Hormones, Women’s Cancers
Updated on: June 20, 2003
Bobbie S. Gostout, M.D., Assistant Professor, Department of Gynecologic Surgery, Mayo Clinic, Rochester, Minn.
These days it seems impossible to read a magazine, watch TV or listen to the radio, without encountering some message about hormone therapy. What makes it confusing is that from day to day and week to week, the messages may be conflicting. One day you read that birth control pills cause cancer, the next that birth control pills prevent cancer.
One year, hormones after menopause are touted as a good idea, the next year, hormones are said to be dangerous. How can women make sense of the information and make appropriate decisions regarding hormone replacement therapy (HRT)?
"In partnership with their physicians, women must make decisions using the best information available today," said Eva Chalas, M.D. associate professor, Department of Obstetrics, Gynecology and Reproductive Medicine, University of New York at Stony Brook and chief, Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Winthrop University Hospital.
Although some information about hormones and cancer must still be resolved, there are two specific points where the information appears clear. The first involves excess estrogen.
"There is clear evidence regarding the impact of excess estrogen. The two female hormones estrogen and progesterone must be in balance in a woman’s body, or she will be at high risk for endometrial cancer," explained Don J. Hall, M.D., gynecologic oncologist at Baptist Medical Tower, Knoxville, Tenn. "Estrogen excess may occur naturally, usually due to obesity, or may be the result of medication. With birth control pills and when estrogen and progesterone are given together for post-menopausal hormone replacement, women receive the combination of estrogen plus progesterone they need to maintain a healthy balance and prevent uterine cancer. After hysterectomy, estrogen can safely be used without progesterone."
The protective effect of oral contraceptives also appears certain. It has been about 45 years since the first women began taking oral contraceptive pills (OCP) in clinical trials. Since that time this remarkable form of contraception has revolutionized women’s lives by permit-ting control over the timing of childbearing. It is now clear that these same pills help to prevent ovarian and uterine cancer as well.
"That protection is evident from even a single year of use," said Dr. Hall, "and OCP use for ten or more years is associated with more than 50% reduction in risk for ovarian and endometrial cancer."
The Women’s Health Initiative
A year ago, one arm of the Women’s Health Initiative (WHI) study, a large clinical trial, was closed when early results showed health risks. This study, conducted by the National Institutes of Health (NIH), showed that when the estrogen Premarin was given daily in combination with the progestin Provera, the overall risks outweighed the benefits.
Regarding cancers, this study showed that there was a small (8 per 10,000 women years) increase in the number of breast cancers diagnosed and a small decrease (6 per 10,000 women years) in the number of colon cancers. The total number of cancers in women on and off the hormones, however, was the same.
The decision to close one arm of this trial was based, in part, on the observation that women taking the combination hormone medications had an increase in cardiovascular events including stroke.
The WHI study took nine years and over 16,000 women participants to reach the point where a decision could be made about the relative risks and benefits of Premarin and Provera for hormone replacement therapy. A second arm of the study in which women who have had a hysterectomy take Premarin alone, is still underway.
At this point, a full 10 years after starting the WHI study, we know one thing for certain: two specific drugs given at specified doses cause small changes in breast cancer and colon cancer risk.
The unanswered questions that emanate from this study, however, are far more numerous. We don’t know the effects of different doses or different medication schedules. We don’t know the effects of the same estrogen with a different progestin or the same progestin with a different estrogen. It is not clear that the same risks pertain to estrogens and progesterones taken in the form of a skin patch instead of a pill. There may be cancer causing or cancer protective effects that only become evident years after these women stop taking hormone medication. These are among the many questions that must be answered by future clinical trials.
"While it is distressing to consider all that is not known, women need not feel overwhelmed," said Dr. Chalas. "The associations between cancer and hormones that are still unclear are likely to be weaker and therefore less important associations than those already evident with today’s research. With this likelihood in mind, women entering menopause should consult their physicians to discuss and weigh the risks and rewards of hormone medications in light of their own health and family histories. Women should also be encouraged to embrace established cancer risk-reducing strategies to further diminish their risk for gynecologic and other cancers."
This article by the Gynecologic Cancer Foundation originally appeared in an advertising supplement to the New York Times on Sunday, June 22, 2003.
GCF gratefully acknowledges Aventis Oncology for its generous support of this educational supplement. The content of this supplement is the work of many individuals and does not reflect commercial interests.
Aventis Pharmaceuticals
www.AventisOncology.com