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Cellular Marker Indicates Tumor Response to Erlotinib

Low compliance found with a second chemotherapeutic agent used to treat breast cancer

MONDAY, Jan. 14 (HealthDay News) -- Response to erlotinib, the epidermal growth factor responsible for inhibiting breast cancer proliferation, can be monitored post-surgically based on various cellular markers, according to study findings published online Jan. 7 in the Journal of Clinical Oncology. A second study in the same issue notes that about one-quarter of breast cancer patients are not adherent to anastrozole therapy.

In the first study, Marta Guix, M.D., from Vanderbilt University School of Medicine in Nashville, Tenn., and colleagues treated 41 patients with stage I to IIIA invasive breast cancer with erlotinib for six to 14 days before surgery and assessed changes in tumor proliferation (based on Ki67 expression) and apoptosis after surgery.

The investigators found that erlotinib inhibited tumor proliferation as well as both the expression of epidermal growth factor receptor and human epidermal growth factor receptor 2 (HER-2). Proliferation was inhibited in estrogen receptor-positive cancers but not HER-2-positive or triple-negative cancers. "A presurgical approach to evaluate cellular responses to new drugs is feasible in breast cancer," Guix and colleagues conclude.

The study was partially funded by Genentech.

In the second study, Ann H. Partridge, M.D., from the Dana-Farber Cancer Institute in Boston, and colleagues examined adherence (at least 80 percent of days covered) to anastrozole therapy in over 12,000 women from three datasets with early-stage breast cancer.

The researchers found that mean adherence during the first year of treatment ranged from 82 percent to 88 percent, with 19 to 28 percent of women classified as non-adherent, and adherence decreased with time. "A substantial proportion of women with early-stage breast cancer may be suboptimally adherent to adjuvant anastrozole therapy," Partridge and colleagues conclude.

Abstract - Guix
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Abstract - Partridge
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