Abstract P6-08-05: United States real-world drug utilization patterns and associated overall survival in Medicare patients with newly-diagnosed metastatic triple negative breast cancer using surveillance, epidemiology, and end results-Medicare data
Authors: Aly A , Shah R , Hill K , Waldeck AR , Botteman M 
Published: February 2018

Background: Limited information is available about treatment patterns for elderly patients (pts) with metastatic triple negative breast cancer (mTNBC). This analysis characterized real-world drug utilization patterns and associated overall survival (OS) for Medicare mTNBC pts.

Methods: Pts ≥66 years of age who were newly diagnosed with mTNBC between 2004 and 2011 were identified from the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database. Triple negative status was obtained from the SEER registry, except for HER2 that was unavailable from 2004-2009 during which we assumed that pts who had a claim for a HER2 test followed by absence of hormonal therapy to be presumed HER2 negative. Pts were followed from diagnosis to death, Medicare disenrollment, HMO enrollment, or 12/31/2013 (whichever occurred first) to characterize the sequence of chemotherapy received – first regimen (1R), second regimen (2R), and third regimen (3R) and median (interquartile, IQR) duration of and between regimens. OS estimates were reported using the Kaplan-Meier method.

Results: Among 694 mTNBC pts, 69 died within 30 days of diagnosis and were excluded. In the remaining 625 pts observed from 2004 through 2013 (median age: 75 years; Charlson comorbidity index (CCI) ≥2: 21%; and median follow-up: 11.4 months), 317 (51%) received chemotherapy. Of the 317 pts, 161 got only 1R, 88 got only 2R, and 68 got 3R+. Compared to pts on 1R, pts on 2R were significantly younger (median age: 2R, 72; 1R, 75 years), married (2R, 40%; 1R, 30%), had fewer comorbidities (CCI≥2: 2R, 16%; 1R, 23%). The top 2 most commonly prescribed single agents in 1R, 2R, and 3R were: 1R, paclitaxel followed by capecitabine; 2R, capecitabine followed by paclitaxel; 3R, gemcitabine followed by capecitabine. The most common combination regimen given was taxane-based in 1R (57%) and 2R (70%).

Drug utilization patterns First Regimen (n=317)Second Regimen (n=156)Third Regimen (n=68)Single Agent205 (65%)74 (47%)40 (59%)Microtubule inhibitors80 (39%)23 (31%)NRPaclitaxel72 (35%)18 (24%)NRAnthracyclines29 (14%)13 (18%)NRDoxorubicin27 (13%)13 (18%)NRAntimetabolites/Others96 (47%)38 (51%)27 (73%)Capecitabine51 (25%)20 (27%)NRGemcitabineNRNR13 (35%)OthersNRNRNRCombination Regimens112 (35%)82 (53%)28 (41%)Taxane-based64 (57%)57 (70%)NRNR, not reported per DUA with NCI. %, col. % relative to single/comb. category

Median (IQR) durations of 1R, 2R, and 3R were 2.7 (1.4-4.4), 3.1 (1.6-5.0), and 2.3 (0.9-4.5) months, respectively. Median time from diagnosis to start of 1R was 1.6 (0.9-2.8) months. Median time to start of 2R and 3R after the end of the previous regimen was 4.6 (2.1-8.1), and 6.2 (3.3-11.0) months, respectively. The median (12-month) OS was 7 months (34%) for all pts and ranged from 3.5 (17%) in the untreated to 25.3 (88%) months in 3R+ pts.

Conclusions: About half of Medicare mTNBC pts do not receive chemotherapy in the real world. Paclitaxel and capecitabine were the most commonly used single agents and taxane-based combination therapy was the most commonly used combination.

Citation Format: Aly A, Shah R, Hill K, Waldeck AR, Botteman M. United States real-world drug utilization patterns and associated overall survival in Medicare patients with newly-diagnosed metastatic triple negative breast cancer using surveillance, epidemiology, and end results-Medicare data [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-08-05.