Hormone Replacement Therapy Risk Benefit

Major news magazines, TV documentaries, radio talk show hosts and other media have paid a great deal of attention to the findings from two studies on hormone replacement therapy. A long-term study of more than 16,000 women between the ages of 50 and 79 revealed that HRT did pose some major health risks.

When you look at the numbers, the risks seem small. Let’s look at the math. Suppose you live in a town in which 10,000 women are taking an estrogen-progestin combination. Of those 10,000 women, chances are that eventually 30 of them will develop breast cancer, as that rate (0.3 percent) is the figure for women in general. What recent HRT research shows, however, is that it’s more likely that 37 women in your town will get breast cancer because of the HRT. That’s an extra 7 women. Now just an additional 7 women out of a population of 10,000 women doesn’t seem like many—that is, unless you’re one of those women!

The research also revealed that you’d expect about 18 in a normal population of 10,000 women to develop blood clots. Among women using HRT, though, that number increases to 36. The number doubles. In statistical terms, that’s a 100 percent increase in the likelihood of getting blood clots. Those health risks were too high to allow the study to continue.

Risks and Benefits

The Women’s Health Initiative (WHI), a group studying HRT effects among 16,000 women, found both benefits and risks to hormone replacement. Here is a summary of their research findings:

Heart Attacks, Strokes and Blood Clots
The study found that HRT increased the risk of having a heart attack or a stroke at a rate of 7 and 8 per 10,000, respectively. The risk of blood clots increased by 18 per 10,000.

Breast Cancer
Many studies in the past gave the medical community reason to suspect that HRT might pose an extra risk for breast cancer. The study found that, like strokes, the risk increased by 8 women per 10,000.

Colorectal Cancer and Hip Fractures
While we’ve heard much about increased risks, as doctors have long suspected some conditions actually benefit from HRT.

Many physicians prescribe HRT to prevent bone loss from osteoporosis. Brittle bones lead to fractures and a decrease in an aging woman’s quality of life. The incidence of hip fractures among women taking HRT decreased by 5 per 10,000 women.

Additionally, the incidence of colorectal cancer (cancer involving both the colon and rectum) decreased by 6 women per 10,000.

Endometrial Cancer
The use of HRT did not appear to pose any additional risk of endometrial cancer, nor did it provide any significant health benefit.

Overall Findings
When all the results were combined, the health risks of HRT so outweighed the benefits that the researchers were forced to recommend that women stop taking estrogen/progestin combinations.

According to the WHI, per 10,000 women on HRT, risk of . . .

  • breast cancer increased by 8.
  • colorectal cancer decreased by 6.
  • heart attacks increased by 7.
  • hip fractures decreased by 5.
  • blood clots increased by 18.
  • stroke increased by 8.

More Evidence

Within just days of the WHI announcement, a study by the National Cancer Institute was published in the Journal of the American Medical Association (July 2002). It revealed that women taking estrogen alone (without progestin) were at high risk for ovarian cancer.

While physicians had established that women should plan to take estrogen for at least ten years to derive the benefits of preserved bone mass and relief from the ravages of osteoporosis, the National Cancer Institute’s study found that taking estrogen for ten years increased a woman’s risk of ovarian cancer by 60 percent. And women who took estrogen for 20 years would triple their risk of ovarian cancer.

The National Cancer Institute studied 44,000 women for more than 20 years. Their findings have implications for the almost 8 million women in the U.S. who take estrogen every day.