MONDAY, Oct. 23, 2006 (HealthDay News) -- Not every breast cancer patient needs to turn to aromatase inhibitor drugs after using tamoxifen for five years, a new study suggests.
While some women definitely stay cancer-free longer by taking the drugs, others do fine without them, and so their use should be weighed carefully, said Dr. Gary M. Freedman, a radiation oncologist at Fox Chase Cancer Center in Philadelphia. He is the lead author of the study published in the Dec. 1 issue of Cancer.
In recent years, aromatase inhibitors have been given to postmenopausal women after using the breast cancer drug tamoxifen. The new study suggests re-thinking universal use of aromatase inhibitors because many women may not need them.
"One message from the study is the majority of women, by the time they finish surgery, radiation and five years of tamoxifen, have a very good prognosis at that point," said Freedman. "The vast majority of these women have been cured after the five-year mark on tamoxifen."
Tamoxifen, in use for more than 20 years, works against the effect of the hormone estrogen, which promotes the growth of breast cancer cells. The newer aromatase inhibitors (such as Femara, Aromasin or Arimidex) interfere with an aromatase enzyme and also reduce estrogen.
Freedman's team looked at 471 women, all treated with breast-conserving surgery, lymph node dissection and radiation after they received a diagnosis of breast cancer in the years 1982 to 1999, "before aromatase inhibitors came out," he said. They all received tamoxifen.
He looked at subgroups of these women to see if most of them would have actually benefited from the additional aromatase inhibitor treatment, evaluating such factors as how many lymph nodes were involved and their menopausal status.
Freedman concluded that the extra treatment in this group of women would have provided only marginal benefit. "The key is to be very selective about who is going to benefit the most from the medication," he said. Those who were premenopausal at the time of the diagnosis and those who had four or more lymph nodes positive for cancer would have been helped the most.
Freedman's team followed the women for a median of 8.25 years. During that time, they found 10 breast cancers in the other breast and 26 recurrences.
At the end of the follow-up period, 45 women had died; eight from breast cancer, the other 37 from other causes, Freedman said. Of those 37, 32 were women over age 60.
Freedman's study follows a large randomized study published last year in the Journal of the National Cancer Institute. Researchers followed more than 5,000 women, half given Femara and half not, and found the aromatase inhibitor improved disease-free survival.
But, Freedman said, "their study didn't go into the kind of detail we did, trying to separate out which subgroups benefit and which didn't."
The new study points out an important fact about decisions about breast cancer treatments, said Dr. Len Lichtenfeld, deputy chief medical officer for the American Cancer Society. "Ultimately, these are individual decisions," he noted. "Women have to turn to their oncologist to get accurate and honest information about the benefits and the risks of the treatments recommended."
Like all drugs, the aromatase inhibitors have drawbacks, Lichtenfeld and Freedman pointed out. Cost is one, with a typical monthly fee of more than $200 in the United States. The aromatase inhibitors can also cause hot flashes, loss of appetite and boost the risk of getting osteoporosis.
But some women may still choose to take the drugs, Lichtenfeld said. "Once breast cancer recurs, it is difficult to get it back under control," he said. As a result, he said, there are likely to be women, after being informed of the risks and benefits, who will choose to take the drugs even if they boost the chance of disease-free survival by only a modest amount.
The same advice of tailoring the treatment to the person was echoed by a panel of advisors to the Food and Drug Administration on Oct. 18. It recommended that breast cancer patients be told in the prescribing information for the drug tamoxifen that if they have a certain genetic profile or take specific antidepressants, it might raise their risk of cancer recurrence.
Some people carry an inactive copy of an enzyme that prevents the body from breaking down some drugs, including tamoxifen, potentially boosting their risk of recurrence. And some research has shown that women on certain antidepressants fare worse on tamoxifen treatment.
To learn more about hormone therapy for breast cancer, visit the American Cancer Society.