31st Annual San Antonio Breast Cancer Symposium

Published: Tuesday, Jan 27, 2009
Couldn’t make it to the Henry B. Gonzalez Convention Center in San Antonio, TX December 10–14, 2008 for the San Antonio Breast Cancer Symposium (SABCS)? Don’t worry, we’ve got you covered, with highlights straight from the convention center, thanks to our editors, who covered the best of the 2008 SABCS. This year’s symposium, the first SABCS to be presented by the CTRC, AACR, and the Baylor College of Medicine, encompassed “the full spectrum of breast cancer research” and was designed to “facilitate the rapid transition of new knowledge into improved care for breast cancer patients.”

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

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 withlow- 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 with5 years of tamoxifen regardless of received treatment. Moreover, sequencing tamoxifen followed by anastrozole improved overall survival by 23% (P=.025) compared with5 years of tamoxifen. “Deathwas 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.

Communicating Risk Prediction of Breast Cancer for an Individual Woman an Elusive Goal

When an individual patient asks a physician, “What is my risk of getting breast cancer,” the physician has little to offer. “For a woman sitting in my office, her risk is either 0 [she won’t get breast cancer] or 100% [she will get breast cancer],” explained JoAnn Elmore, MD, University of Washington, Seattle, WA. “The ideal risk model needs to work well for the individual woman, so we can counsel her, but we have lots of work to do before we have an ideal risk prediction model,” she said.

The Gail model, developed in 1989, is widely used to estimate expected cancer incidence among populations, but not individuals. This model is based on agreed-upon risk factors that include age, age at first period, age at first birth/or nulliparity, number of first-degree relatives with breast cancer, and history of benign atypical hyperplasia of the breast.

“Websites, such as the American Cancer Society, get hundreds of thousands of hits by women attempting to use this model to estimate their risk of developing breast cancer,” Elmore explained.

A study by Rockhill et al. attempted to validate the Gail model in 82,109 women enrolled in the Nurses’ HealthStudy. Over the first five years of the study, about 1000 women developed breast cancer (1.65%). The expected incidence, according to the Gail model, was 1.55%, “so the risk model worked well at a population level,” Elmore said.

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