Temporal and Regional Trends in Use of Chemotherapy Regimens in Advanced Colorectal Cancer

Abstract

Introduction: Chemotherapeutic management of advanced colorectal cancer (CRC) has evolved with the availability of biologic agents. However, the pattern of use of these agents in the United States is unclear. Hence, we studied the temporal and regional trend in first-line chemotherapy regimens in patients with stage III/IV CRC between 1997-2007, in a nationally representative database. Methods: We used surveillance, epidemiology, and end results-Medicare (SEER-Medicare) linked database to identify first-line chemotherapy in 29,714 elderly patients (≥66 years) with stage III/IV CRC. Chemotherapy regimens were divided into: biologic-based including bevacizumab, cetuximab, and/or panitumumab; 5-fluorouracil/ leucovorin-based; irinotecan-based; oxaliplatin-based; others; no chemotherapy. Risk-standardized treatment rates and temporal (1997-2002, 2003-05 and 2006-07) and regional trend (based on quintiles of hospital referral regions) in use of these regimens was estimated using a logistic hierarchical generalized linear model. Results: Over time, we observed a progressive increase in the use of biologic (1997-2002: 0%; 2003-05: 2.8%; 2006-07: 7.3%) and oxaliplatin-based (1997-2002: 0%; 2003-05: 10.1%; 2006-07: 18.2%) chemotherapy for first-line treatment of advanced CRC, both on unadjusted (Figure 1) and adjusted analysis. Concomitantly, there was decline in the use of 5-FU (1997-2002: 41.0%; 2006-07: 19.2%) and irinotecan-based therapy (1997-2002: 5.4%; 2006-07: <1%). The proportion of patients opting against any chemotherapy remained the same (52.6-52.9%). This temporal trend was seen across all hospital referral regions across all therapies, with no significant regional variation; 6.7-8.0% of patients across all regions were receiving first-line biologic-based chemotherapy in 2006-07.Figure 1: Temporal trend in first-line chemotherapy regimens in patients with stage III/IV colorectal cancer.Conclusion: Based on analysis of the SEER-Medicare database, there has been a shift towards biologicand oxaliplatin-based regimens as first-line chemotherapy for advanced CRC from 1997 to 2007, across all regions in the United States, without significant geographic variability. Effect on treatment outcomes as well as financial implications merit further evaluation.