Treatment patterns and outcomes in metastatic colorectal cancer (mCRC).

Abstract

699 Background: Treatment (tx) selection for mCRC is multifactorial and affected by patient (pt) and disease factors, comorbidities, and previous tx. Few agents existed for therapy after second progression (i.e. third line (3L) at the time of this study. We aimed to capture mCRC tx patterns up to 3L and associated clinical and economic outcomes. Methods: A retrospective observational study of mCRC pts initiating 1L tx from 1/1/07 to 6/30/11 and 3L tx before 6/30/12. Data was extracted from The US Oncology Network (USON)/McKesson Specialty Health EHR and claims database. Pts on clinical trial or with another cancer diagnosis were excluded. Tx was organized into tx backbone categories and lines of therapy (LOTs), and adherence to NCCN guidelines and USON pathways assessed. The Kaplan-Meier method was used to estimate overall survival (OS). A multivariable generalized linear regression model was used to evaluate total costs during 3L tx as a function of 3L covariates by Medicare allowable. Clinical outcomes in 3L have been previously reported. Additional information on cost and other utilization is provided. Results: Of756 eligible 1L pts, 577 pts received 3L tx. At 1L, median age was 61 yrs (range 26-90+), male (55%), normal BMI (43%), ECOG performance status (PS) of 1 (65%), and Medicare (39%) insurance. The most utilized txs in 1L, 2L, and 3L were oxaliplatin-based (FOLFOX + bevacizumab, 46%), irinotecan-based (FOLFIRI + bevacizumab, 23%), and irinotecan + anti-EGFR (irinotecan + cetuximab, 24%) respectively. Adherence to NCCN and USON recommendations for 1L, 2L, and 3L was 88%/75%/55% and 84%/62%/38% respectively. OS in 3L was influenced by PS, BMI, and KRAS (p < 0.05), but was not different by tx backbone (p = 0.47). In the multivariable model of total cost per pt in 3L, there were no significant predictors. Conclusions: Knowledge of tx sequencing aids in understanding selection choices and outcomes in pts who are candidates for later lines of therapy of mCRC. High utilization of targeted therapies was observed in each line. Adherence to guidelines decreased with increasing lines of therapy. Utilization and costs by tx backbone in the 3L during this time frame varied. 3L OS did not differ according to tx backbone.