SABCS Report: Tackling the Optimal Use of Established Therapies

Ben Leach
Published: Wednesday, Feb 06, 2013
Dr. Debu Tripathy
Debu Tripathy, MD

Dr. William Gradishar
William Gradishar, MD
The search for the appropriate duration of therapy for long-term treatment of patients with breast cancer and the continuing challenges of identifying which patients would benefit from novel treatments were among the most-discussed topics at the 2012 CTRC-AACR San Antonio Breast Cancer Symposium in Texas.

More than 1000 abstracts were featured during the symposium, which drew approximately 7500 oncologists, researchers, and other oncology specialists from around the world to the Henry B. Gonzalez Convention Center.

Much of the discussion revolved around whether more treatment translates into a greater clinical benefit. In the case of tamoxifen and fulvestrant (Faslodex), women with hormone-responsive breast cancer may benefit from longer durations or higher doses of these therapies in the long-term, research indicated. However, that was not the case with trastuzumab (Herceptin), where one year of therapy appeared to have just as much benefit as two years of the drug for HER2-positive breast cancer.

Finding the right therapies has also proved challenging. Multiple studies failed to show that bevacizumab (Avastin) improved survival across all breast cancer patients, though some subgroups may experience modest benefits. After gaining approval more than a year ago in later lines of therapy, eribulin mesylate (Halaven) for earlier-line therapy has failed to show superiority over capecitabine (Xeloda), a drug that has been widely available for a longer period of time.

Some emerging therapies appear to have promise, such as a novel drug that significantly improved progression- free survival in women with estrogen receptor (ER)-positive breast cancer.

In interviews with OncologyLive, Debu Tripathy, MD, co-leader of the Women’s Cancer Program and professor of Medicine at the University of Southern California/ Norris Comprehensive Cancer Center in Los Angeles, California, and William Gradishar, MD, Betsy Bramsen Professorship of Breast Oncology and a professor of Medicine-Hematology/Oncology at Northwestern University Feinberg School of Medicine in Chicago, Illinois, discussed their views of the most important abstracts presented during the symposium.

10-Year Tamoxifen Regimen Superior

A large study involving women with ER-positive breast cancer found that patients who received 10 years of treatment with tamoxifen had fewer recurrence events and fewer deaths than patients who received five years of treatment with the drug.1

“Ongoing hormonal therapy is something that has been investigated, but we have very little data beyond five years of treatment,” Tripathy said. “We know in the case of tamoxifen that five years is certainly better than one or two years, but we also know that after five years of therapy, patients are still at risk for recurrence.”

The ATLAS trial enrolled 6846 women with ER-positive breast cancer between 1996 and 2005. All of the women used tamoxifen for at least four years, after which patients were randomized to either continue treatment with tamoxifen for another five years or stop treatment with tamoxifen immediately.

Gradishar said that the most striking aspect was that researchers observed little difference in recurrence rates and death rates between the two groups in years five through nine. However, during the second decade after diagnosis, patients who continued on tamoxifen for 10 years had a 25% lower recurrence rate and a 29% lower breast cancer mortality rate compared with women who received tamoxifen for five years.

Overall, the risk for death from breast cancer between five and 14 years after diagnosis was 12.2% in patients who received 10 years of tamoxifen compared with 15% in patients who stopped taking tamoxifen after five years, with the greatest benefit being observed between years 10 and 14. Patients who continue on tamoxifen are at risk for developing endometrial cancer, though the disease is generally curable and the reduced risk of death from breast cancer heavily outweighs the risk of death from endometrial cancer.

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