Aromatase Inhibitors Improve Breast Conservation Rates

Similar breast cancer surgical outcomes with exemestane, letrozole, or anastrozole pretreatment

THURSDAY, May 12 (HealthDay News) -- Patients with clinical stage II to III estrogen receptor (ER)-positive breast cancer who undergo preoperative treatment with the aromatase inhibitors (AIs) exemestane, letrozole, or anastrozole have improved surgical outcomes, according to a study published online May 9 in the Journal of Clinical Oncology.

Matthew J. Ellis, Ph.D., from Washington University in St. Louis, and colleagues compared the responses to preoperative treatment with three AIs in 377 postmenopausal women with clinical stage II to III ER-positive breast cancer (Allred score 6 to 8). Participants were randomly assigned to receive neoadjuvant exemestane, letrozole, or anastrozole. Clinical response to treatment, breast conserving surgery (BCS), Ki67 proliferation marker changes, the Preoperative Endocrine Prognostic Index (PEPI), and PAM50-based intrinsic subtype analysis were the end points of the study.

The investigators selected letrozole and anastrozole for further investigation on the basis of clinical response rates but found no differences in surgical outcome, PEPI score, or Ki67 suppression for the three agents. The BCS rate after treatment was 51 percent for patients who were designated candidates for mastectomy at presentation. AI-unresponsive nonluminal subtypes (human epidermal growth factor receptor 2 enriched or basal-like) were identified in 3.3 percent of the patients based on PAM50 analysis. Luminal A (LumA) and luminal B tumors had similar clinical responses and surgical outcomes, but PEPI of zero (best prognostic group) was highest in the LumA subset (27.1 versus 10.7 percent).

"The results from this study confirm earlier trial results demonstrating that marked improvements in surgical outcomes are achievable with neoadjuvant aromatase inhibitor therapy," the authors write.

Several authors disclosed financial relationships with pharmaceutical companies, including Pfizer and Novartis, which supported the study.

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