A retrospective observational study to estimate the attrition of patients across lines of systemic treatment for metastatic colorectal cancer in Canada

Background: Selection and sequencing of treatment regimens for individual patients with metastatic colorectal cancer (mcrc) is driven by maintaining reasonable quality of life and extending survival, as well as by access to and cost of therapies. The objectives of the present study were to describe, for patients with mcrc, attrition across lines of systemic therapy, patterns of therapy and their timing, and KRAS status. Methods: A retrospective chart review at 6 Canadian academic centres included sequential patients who were diagnosed with mcrc from 1 January 2009 onward and who initiated first-line systemic treatment for mcrc between 1 January and 31 December 2009. Death was included as a competing risk in the analysis. Results: The analysis included 200 patients who started first-line therapy. The proportions of patients who started second-, third-, and fourth-line systemic therapy were 70%, 30%, and 15% respectively. Chemotherapy plus bevacizumab was the most common first-line combination (66%). The most common first-line regimen was folfiri plus bevacizumab. KRAS testing was performed in 103 patients (52%), and 38 of 68 patients (56%, 19% overall) with confirmed KRAS wild-type tumours received an epidermal growth factor receptor inhibitor (egfri), which was more common in later lines. Most KRAS testing occurred after initiation of second-line therapy. Conclusions: In the modern treatment era, a high proportion of patients receive at least two lines of therapy for mcrc, but only 19% receive egfri therapy. Earlier KRAS testing and therapy with an egfri might allow a greater proportion of patients to access all 5 active treatment agents.