Early Breast Cancer Patients Live Longer on Sequencing Tamoxifen and Anastrozole Versus 5 Years of Tamoxifen

DECEMBER 11, 2008
Alice Goodman
Giving tamoxifen for 2 years followed by 3 years of anastrozole (sequencing strategy) improved relapse-free survival and overall survival compared to 5 years of tamoxifen in postmenopausal women with newly diagnosed, hormone-sensitive, early breast cancer, according to analysis of the sequencing arm and the total population in the large, prospective, randomized ABCSG 8 trial.

Although other landmark trials of adjuvant hormonal therapy have confirmed the superiority of aromatase inhibitors (AIs) over tamoxifen in preventing breast cancer recurrence in patients with early breast cancer, ABCSG is the first to show that patients live longer when treated with an AI. “As distinct from other trials, mature data from ABCSG 8 show a high overall survival benefit,” said Raimund Jakesz, MD, Vienna Medical School, Austria, who presented results.

The study enrolled postmenopausal women with low- to intermediate-risk, estrogen receptor-positive/progesterone-receptor-positive (ER+/PgR+), ductal cancer grade 1 or 2, and lobular cancer (18%). Dr. Jakesz pointed out that ABCSG 8 had several unique factors compared with other AI trials: including lobular cancer, including women age 80 years and younger, and not allowing chemotherapy.

ABCSG 8 was originally designed to compare tamoxifen for 2 years followed by tamoxifen for 3 years versus tamoxifen for 2 years followed by anastrozole for 3 years. The trial was stopped early in 2004, and women in the tamoxifen alone arm were allowed to cross over to the sequencing arm.

A benefit of sequencing was observed regardless of age, Dr. Jakesz said. “Women with high expression of ER/PgR did particularly well,” he noted. Those with ER+++/PgR+++ enjoyed longer relapse-free survival and overall survival, he noted.

Analysis of 2922 patients (including crossovers to the sequencing arm) showed that sequencing significantly improved relapse-free survival by 21% (P=.038) compared with 5 years of tamoxifen regardless of received treatment. Moreover, sequencing tamoxifen followed by anastrozole improved overall survival by 23% (P=.025) compared with 5 years of tamoxifen. “Death was reduced in women without recurrence as well as those with recurrence,” Dr. Jakesz stated.

Analysis of the total study population of 3714 showed that sequencing therapy with anastrozole improved relapse-free survival by 27% (P=.001) in patients according to actually received therapy, and sequencing improved overall by 22% (P=.032).

The study turned up no new concerns about safety. As in previous trials, more bone and joint pain was reported in patients taking an AI, and more gynecologic symptoms were reported in the tamoxifen group.

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