First-line Palliative Chemotherapy for Colorectal Cancer: a Population-based Analysis of Delivery and Outcomes in a Single-payer Health System.

AIMS: Clinical practice guidelines recommend palliative chemotherapy for most patients with metastatic colorectal cancer. However, outcomes observed in the real world compared with patients enrolled in clinical trials have not been sufficiently described. The objective of this study was to evaluate the delivery and outcomes of first-line palliative chemotherapy administered to patients with colorectal cancer in routine clinical practice compared with clinical trials.

MATERIALS AND METHODS: Using linked health administrative data, we carried out a retrospective population-level cohort study on patients diagnosed with colorectal cancer in Ontario, Canada from 2010 to 2019. Patient, disease and treatment characteristics were summarised. The primary outcome was median overall survival, stratified by treatment prescribed and age. Demographics and outcomes in this real-world population were compared with those from pivotal clinical trials. A multivariable Cox regression model reporting hazard ratios and 95% confidence intervals was used to determine factors associated with survival in patients receiving systemic treatment.

RESULTS: We identified 70 987 patients with a new diagnosis of colorectal cancer, of which 4613 received first-line chemotherapy for unresectable locally advanced or metastatic disease and formed the study cohort. Fifty-eight per cent were male and the mean age was 63 years. Most had colon cancer (69%), at least one comorbidity (73%) and lived in an urban location (79%). Less than half (47%) had surgery after diagnosis. The most common regimen prescribed was folinic acid, 5-fluorouracil and irinotecan (FOLFIRI) with bevacizumab or epidermal growth factor receptor inhibitors (EGFRi; n = 2784, 60%). Among all treated patients, the median overall survival was 17.1 months, with survival difference by regimen [median overall survival 18.3 for FOLFIRI with bevacizumab or EGFRi, 19.6 for folinic acid, 5-fluorouracil and oxaliplatin (FOLFOX)/capecitabine, oxaliplatin (XELOX) with bevacizumab or EGFRi, 13.6 for FOLFIRI alone and 7.8 for 5-fluorouracil or capecitabine]. Patients aged >80 years were most likely to have received single-agent 5-fluorouracil or capecitabine, and had inferior overall survival compared with their younger counterparts. Compared with pivotal clinical trials, patients in the real world had inferior overall survival outcomes despite similar demographic characteristics (including age and sex).

CONCLUSIONS: In this real-world population-based analysis of patients receiving first-line chemotherapy for unresectable locally advanced or metastatic colorectal cancer, survival outcomes were inferior to those reported in randomised trials despite similarities in age and sex. This information can be used when counselling patients in routine practice about expected outcomes.