Changes in adjuvant breast cancer chemotherapy regimen selection over time in the community.

Abstract

6109 Background: Adjuvant breast cancer (BC) chemotherapy (CT) treatment has evolved over time due to improved understanding of risk conveyed by pathology and patient (pt) characteristics, as well as emergence of new and mature data for survival and toxicity. We aimed to evaluate how CT regimen selection has changed in recent years in various subgroups. Methods: Using iKnowMed EHR data from The US Oncology Network, we retrospectively identified female pts diagnosed with stage I-III BC between 1/2007 and 12/2010 at practices with EHR data available at time of diagnosis. Pts with <5 office visits, those with a second primary or previous cancer diagnoses were excluded. Age, ER, HER2, nodal status, stage and year of diagnosis were captured. CT utilization was determined by the number of pts who received CT within 6 months of their diagnosis. Clinical trial pts were included. Regimens were categorized by the initial CT title and drugs assigned. Pts with metastatic regimens were excluded. CT regimens were analyzed by subgroups and trended over time. Results: During the time period, 26,095 stage I-III BC pts were identified. A CT regimen within 6 months of diagnosis was documented in 56% of pts. CT utilization was 83% in HER2+ pts, 85% in ER-/HER2- pts, and 45% in ER+/HER2- pts. CT utilization decreased overall with increasing pt age (71%, 64%, 51%, 33%, and 13% for pts in their 4th, 5th, 6th, 7th and ≥8th decade of life). In HER2+ pts, use of non-anthracycline containing regimens increased from 26 to 62%, and anthracyline-taxane combination regimens decreased from 33 to 15%. In HER2-/ER+ pts, the most used non-anthracycline regimen was docetaxel + cyclophosphamide (TC) at 41%. Anthracycline-taxane combinations were used more often in the HER2-/ER- group (32%). Conclusions: In the 4 year study period, this data suggests that ER and HER2 status may drive chemotherapy choice more than nodal status. Anthracycline containing regimens are being used less often possibly due to similar efficacy but less cardiac toxicity, particularly when combined with trastuzumab. These results suggest a change away from anthracyclines in specific subgroups with the controversy over the benefits of that change unsettled, and cost implications yet unquantitated.