Geographic practice patterns in the selection of adjuvant dose dense (DD) chemotherapy among stage 1 breast cancer (BC) patients.

Abstract

126 Background: Oncology Analytics (OA) reviewed drug pre-authorization requests amongst populations with similar demographic features. Small stage I, node-negative, margin-free BC may be treated by observation, hormone therapy or adjuvant chemotherapy. If chemo is used, either standard or DD schedules may be requested. Patient age, HER2 status, and ER expression affect the choice of treatment. Methods: We analyzed data from oncology drug preauthorization requests for BC protocols submitted by providers in FL, GA and TX from October 1, 2013 through September 30, 2015. Pearson chi-square was used to test for association at 95% CL. Risk was bifurcated by consideration of age, putative ER/PR status, and HER2 status. High-risk patients are those with putative ER/PR(-) status and/or Her2(+) status and/or younger than 50 years old. Results: Requests for standard and DD chemotherapy are related to the risk characteristics of the tumor. Oncologists in GA/TX prescribed a greater proportion of adjuvant chemotherapy for stage I BC patients than oncologists in FL (13.13% GA/TX vs 9.97% FL;p = 0.001). About 40% of all stage 1 chemotherapy requests are for dose-dense chemotherapy. Patients with high risk BC have a higher chance of getting dose dense chemotherapy than the low risk subgroup. FL oncologists have a higher likelihood of prescribing dose-dense chemotherapy than GA/TX oncologists (82% FL vs 65% TX p < 001) if the BC risk is high, whereas the opposite is true if the patient is low risk (8% FL vs 17% GA/TX, p = 0002). Conclusions: While these geographical differences may be random, it may also be relevant that OA has worked in Florida for six, Georgia and Texas for two years. This suggests that patients with low risk disease are less likely to get the more toxic DD therapy if OA is in a market for a longer period of time.