Keeping Breast Cancer From Coming Back

Women previously treated for breast cancer could benefit from aromatase inhibitors.

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At a 40th birthday celebration, Panina sits in bottom row, second from right.

Last September, I wrote about my friend Panina, 37, whose breast cancer was found on a baseline screening mammogram. After coming through chemotherapy and radiation in a state of grace, she's now taking the anti-estrogen drug tamoxifen, which she'll stay on for five years to lower her chances of recurrence. Lately, given the recent finding that other anti-estrogen drugs often prescribed after tamoxifen—called aromatase inhibitors—can help ward off cancer better than tamoxifen alone, she's wondered if she'll be able to take them and reap the benefit.

Other breast cancer patients are probably asking the same thing: The headline-making study, published in the Journal of Clinical Oncology, found that postmenopausal patients who took the aromatase inhibitor Femara after stopping tamoxifen three years earlier on average had an 80 percent reduced risk of developing a new breast tumor and more than a 60 percent lower risk of life-threatening distant metastases compared with former tamoxifen takers who were given placebos. All in all, those taking Femara after tamoxifen were on anti-estrogen drugs for a total of 10 years. "I think this finding can make a very large difference in the outcome," says study leader Paul Goss, director of breast cancer research at Massachusetts General Hospital in Boston (who is a paid consultant for Novartis, manufacturer of Femara).

Currently, postmenopausal women with the most common kind of tumors that grow in the presence of estrogen are given five years of an aromatase inhibitor (Femara, Arimidex, Aromasin) or a combination of tamoxifen followed by one of these drugs for a total of five years. Either approach prevents recurrences more effectively than tamoxifen alone. Panina and other premenopausal women, though, get only tamoxifen. That's because aromatase inhibitors work by blocking the conversion of other hormones into estrogen; they don't have any effect on estrogen produced by working ovaries. The new finding suggests that younger women could benefit from taking an aromatase inhibitor once they go into menopause, even if they've been off tamoxifen for quite a while, says Nancy Lin, a medical oncologist at the Dana-Farber Institute in Boston who wrote an editorial accompanying the study.

Some experts are urging caution. "Do breast cancer patients always have to be taking something to prevent a recurrence? I'm fighting against this notion," says Susan Love, a clinical professor of surgery at the University of California-Los Angeles medical school and president of the breast cancer-focused Dr. Susan Love Research Foundation. She points out that the benefits of tamoxifen have been shown to persist for 15 years or more after women stop taking it. And while the new study showed promising results, she says, the payoffs were still modest: About 2 percent of those taking Femara had a recurrence during the five-year study compared with 5 percent of the placebo takers. There was no difference in death rates from breast cancer.

Side effects are another thing to consider. Like tamoxifen, aromatase inhibitors can cause hot flashes in about a third of women, and they can also trigger arthritislike joint pain, which prompts some women to discontinue therapy. In terms of overall health, tamoxifen protects against bone loss but slightly increases the risk of uterine cancer and blood clots, while aromatase inhibitors have the opposite effects. In fact, the study found that about 5 percent of the women on Femara had a new diagnosis of osteoporosis or a bone fracture during the study period compared with about 3 percent of the placebo group. Women who go on these drugs should get a bone scan every year or two, recommends Lin, and should take a bone-building drug like Fosamax or Actonel if they are found to have low bone density.

Deciding whether or not to take anti-estrogen drugs for a full decade certainly isn't simple. "A woman needs to ask her doctor about her own risk of recurrence," stresses Love, "and how much it will be reduced on these drugs." Someone who has a 10-year recurrence risk of, say, 20 percent may consider the drugs more beneficial than someone with a 5 percent risk. For Panina, the decision will come after menopause. "With the hot flashes I'm having from the tamoxifen, I feel like I'm already there," she tells me at a friend's 40th-birthday dinner.

Toward the end of the party, my friends and I joke about the pros and cons of turning 40 (better sex drive, greater confidence; more body fat, less muscle). Panina, with a wisdom beyond her years, says, "I'll just consider it a blessing when I make it to 40."