Anastrozole Sequence Doesn't Significantly Improve Survival

Sequencing tamoxifen and anastrozole provides limited improvement in breast cancer outcome

TUESDAY, Jan. 24 (HealthDay News) -- Sequencing two years of tamoxifen (TAM) and then three years of anastrozole (ANA) in the first five years of endocrine therapy leads to small, but nonsignificant improvements in breast cancer recurrence, according to a study published online Jan. 23 in the Journal of Clinical Oncology.

Peter C. Dubsky, M.D., of the Medical University of Vienna, and colleagues studied 3,714 postmenopausal women with endocrine receptor-positive G1 or G2 tumors. After surgery, patients were randomly allocated to two years of TAM followed by three years of ANA, or to five years of TAM. Patients were excluded if they had received adjuvant chemotherapy or had G3 or T4 tumors. During a median of 60 months of follow-up, data were examined for 17,563 woman-years. The participants had a median age of 63.8 years; 75 percent of patients were node negative and 75 percent had T1 tumors.

The researchers found that sequencing of ANA after identical two-year treatment with TAM in both arms did not result in a statistically significant improvement of recurrence-free survival (hazard ratio [HR], 0.80; 95 percent confidence interval [CI], 0.63 to 1.01; P = 0.06). Analysis of distant relapse-free survival showed a 22 percent improvement (HR, 0.78; 95 percent CI, 0.60 to 1.00). On-treatment adverse events and serious adverse events were consistent with known toxicity profiles for both agents.

"Despite a low overall rate of recurrence in a population with breast cancer at limited risk of relapse, the a priori sequence strategy of two years of TAM followed by three years of ANA led to small outcome and toxicity benefits," write the authors.

Several authors disclosed financial relationships with pharmaceutical companies, including AstraZeneca, which funded the study and manufactures anastrozole.

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