MONDAY, Dec. 15 (HealthDay News) -- After breast cancer patients undergo surgery and receive tamoxifen, switching to anastrozole may increase the likelihood of disease-free survival but also decrease quality of life. In addition, surgical patients who receive letrozole may have a lower risk of death compared to those who receive tamoxifen, according to research presented at the San Antonio Breast Cancer Symposium held Dec. 10 to 14 in San Antonio, Texas.

In one study, Shozo Ohsumi, M.D., of the NHO Shikoku Cancer Center in Matsuyama, Japan, and colleagues studied 346 patients who continued tamoxifen and 348 patients who switched from tamoxifen to anastrozole. After a median follow-up of 42 months, the researchers found that the anastrozole group had a 31 percent improvement in disease-free survival and a 48 percent improvement in relapse-free survival, but that their health-related quality of life had significantly declined compared to the tamoxifen group.

In a second study, Alan Coates, M.D., and colleagues from the BIG 1-98 Collaborative and the International Breast Cancer Study Group conducted a four-arm and two-arm study to compare outcomes in women who received either letrozole or tamoxifen alone or both of the drugs in sequence. After a median follow-up of 71 months, the investigators found that the letrozole-only group had a 13 percent improvement in survival compared to the tamoxifen-only group and that the sequential treatments did not improve disease-free survival compared with letrozole alone.

"We believe recurrence-free survival rate should be regarded as a more important outcome than quality of life in general," Ohsumi said in a statement. "Therefore, we would advise recurrence-free postmenopausal breast cancer patients who had undergone initial treatment with tamoxifen after surgery to switch from tamoxifen to anastrozole. However, if they experience side effects that make their quality of life worse, such as severe joint pain with anastrozole, we will give patients an option to switch back to tamoxifen with an explanation that tamoxifen will give better quality of life but a little worse recurrence-free survival rate."

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