Analysis of a large cohort of patients with metastatic colorectal cancer who received chemotherapy at academic, private, and community-based oncology practices using the same chemotherapy order entry system showed that “bevacizumab has been more consistently integrated into treatment regimens than anti-EGFR antibody therapies, particularly in first-line therapy. However, treatment choices vary substantially according to specific patient, practice, and provider characteristics,” Thomas A. Abrams, MD, of Dana-Farber Cancer Institute in Boston, and colleagues reported in the Journal of the National Cancer Institute.
The chemotherapy order entry system captured disease, patient, provider, and treatment data for patients who received chemotherapy between January 2004 and March 2011. Of the 4,877 eligible patients who received first-line chemotherapy for metastatic colorectal cancer, 2,575 (53%) went on to receive second-line treatment, 1,373 (28%) received third-line treatment, and 640 (13%) received fourth-line treatment. The investigators noted that between 2004 and 2007, bevacizumab (Avastin), cetuximab (Erbitux), and pantimumab (Vectibix) had all been approved for the treatment of metastatic colorectal cancer.
Most Common Combination
“Throughout the study period, fluoropyrimidine/oxaliplatin combination was the most commonly used first-line chemotherapy regimen, representing 71% of first-line therapy by 2007. First-line bevacizumab use averaged 51%, peaking at 55% in 2006. Of those who received first-line bevacizumab, 34% continued to receive bevacizumab in the second-line,” the researchers wrote.
Only 26% of the patients ever received an anti-EGFR monoclonal antibody, mostly cetuximab. “Patients treated at academic centers, with longer duration of first-line therapy, and at sites in the western United States were statistically more likely to receive an anti-EGFR antibody. Anti-EGFR antibody use fell by 18% after the US Food and Drug Administration limited its use to patients with KRAS wild-type tumors in June 2009,” the investigators stated.
Oncologists at academic centers and those who treated higher volumes patients with colorectal cancer “were more likely to prescribe combination chemotherapy as compared with monotherapy, were more likely to prescribe a biologic agent in the first-line setting, and were more likely to continue bevacizumab into the second-line therapy after progression of a bevacizumab-containing first-line regimen,” the researchers found. Ongoing studies are evaluating the sequence of currently available therapies and “two new agents, ziv-aflibercept [Zaltrap] and regorafenib [Stivarga], were recently added to the arsenal of therapies for patients” with metastatic colorectal cancer. ■
Abrams TA, et al: J Natl Cancer Inst 106(2):djt371, 2014.