Breast Cancer Survivors May Face Fewer Heart Troubles

Study suggests estrogen might offer protection against heart attacks

WEDNESDAY, June 4, 2003 (HealthDayNews) -- There may be good news for women who survive breast cancer: Your risk of heart attack is potentially much lower than women who are cancer-free.

What's more, the reason could hold the clue to helping all women reduce their risk of heart disease, contends new research that is not without its critics.

"Women who have survived breast cancer have had plenty of bad news in their life. Now, for once, there is something good to report," says study author Dr. Elizabeth Lamont, an assistant professor of medicine at the University of Chicago.

That "something," says Lamont, is very early evidence that either having breast cancer or taking one type of breast cancer treatment (SERM drugs such as Tamoxifen) might have some cardio-protective effects.

"Our study has identified a subset of women with a one-third reduction in the risk of heart attack. And with heart disease being the single most significant cause of death in elderly women, this protective effect is definitely significant," says Lamont, whose research appears in the July issue of Cancer.

While Lamont believes the link is estrogen -- either naturally higher concentrations in women who had breast cancer or the result of the SERM drugs that act like estrogens in the body -- not all experts agree.

New York University oncologist Dr. Julia Smith finds the new study provocative, but she's not quick to embrace the thought that either estrogen or SERMS are offering the protective effect.

"What this study tells us is that women who have breast cancer have a reduced risk of heart attack. But it really doesn't offer any solid evidence as to why. And I would not jump to any conclusions about either the protective effects of estrogen or that of SERMs," says Smith, an clinical assistant professor at NYU's School of Medicine.

One reason, she says, is because the research conclusions were drawn using data from a much larger study -- one that identified women with breast cancer but did not indicate the type of tumors found.

"So, we don't really know if these women had estrogen-positive tumors or if excess estrogen even played a role in their breast cancer," Smith says. It's not known for sure if the cardio-protective effects were hormone-driven, she adds.

Smith also points out the data does not indicate which women took SERM drugs or how many did -- another factor that she says makes it impossible to link cardio-protective effects to this medication, or to estrogen in general.

"Perhaps most important is that other major studies of estrogen and SERMs have not found even a hint that this protection exists. So you have to wonder how this new study came to these conclusions," says Smith, who adds it's certainly worth further investigation to learn more.

Lamont concedes she can only estimate that "about half" of the women in the study took SERMs and the rate of estrogen-positive tumors was unknown.

Still, she says, "We don't believe any of the women in the control group had any SERM exposure." And, Lamont adds, other studies have hinted of some cardio-protective effects of SERMS, including not only Tamoxifen but also Raloxifene, which is used to treat osteoporosis.

"So, I don't think the chapter is closed on estrogen, or at least estrogen receptors, just yet," Lamont says.

The study was based on data from the National Cancer Institute's large Surveillance, Epidemiology, and End Results (SEER) study, conducted between 1993 and 1998. For the new research, doctors evaluated data on 5,980 women with a history of early-stage breast cancer, for heart attack risks, and then compared them to a group of 23,165 women who were cancer-free.

The result: Breast cancer survivors showed a 34 percent decreased risk of first acute heart attack when compared to women without breast cancer. This remained true even after the researchers accounted for socioeconomic factors, as well as geographic location and other health factors that could influence the outcome.

"Clearly, the news is good for women who have breast cancer: You are less likely to face cardiac problems, particularly a heart attack, " Lamont says.

Although the authors hint at the idea that estrogen, or the use of SERM drugs, may hold the key to cardio-protection for all women, they admit more studies are needed before any solid conclusions can be drawn.

Smith offers another possibility, pointing out that perhaps women who survive breast cancer are simply a hardier stock, better able to cope with the factors that might otherwise cause you to have a heart attack.

"These are women who have survived the psychological trauma and stress of diagnosis, and the physical and emotional traumas of cancer treatment, at an advanced age. So these are strong women," she says. Strong enough, perhaps, to also overcome the factors that lead to heart disease.

More information

To learn more about the potential benefits of SERM drugs, visit the National Cancer Institute. For more on women and heart disease, check with the National Heart, Lung, and Blood Institute.

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