CAPOX and FOLFOX are widely used chemotherapy regimens for colorectal cancer (CRC). The superiority of one regimen over the other in a real-world setting (RWE) could have significant clinical implications given their common use, but such RWE is limited. This study analyzed provincial database records of 13,461 Canadian patients treated from 2005 to 2017. The primary outcomes were rates of Emergency Department visits and/or hospitalizations (ED/H) and overall survival (OS). CAPOX was used less frequently (8.4%) than FOLFOX (91.6%), often in older patients (p < 0.003 for Stage I–III; p < 0.001 for Stage IV). CAPOX recipients had shorter treatment durations (median 15 vs. 20 weeks, p = 0.002) and higher unadjusted ED/H rates (60.8% vs. 50.9%, p < 0.001), though this difference was nonsignificant on multivariate analysis (MVA) (HR 1.05 (0.92, 1.20), p = 0.466). Patients receiving CAPOX had worse OS than those on FOLFOX, (5-year OS 70.1% vs. 77.2% (p < 0.001) non-metastatic; 16.6% vs. 33.2% (p < 0.001) metastatic). MVA confirmed inferior OS with CAPOX (HR 1.42, p < 0.001). Other predictors of shorter OS included older age, male sex, comorbidities, rural residence, and lower income. This administrative data is at risk of bias but highlights the need for careful patient selection and informed treatment decision making.

Purpose: Pembrolizumab combined with chemotherapy is the standard of care for early-stage triple-negative breast cancer (TNBC) following KEYNOTE-522. However, real-world data on immune-related adverse events (irAEs) remain limited. We evaluated the incidence, severity, and clinical consequences of irAEs in a real-world cohort and compared outcomes with KEYNOTE-522. Methods: We conducted a retrospective cohort study of patients with stage II–III TNBC treated according to the KEYNOTE-522 regimen at two Ontario cancer centres between June 2022 and May 2024. Data on irAEs, treatment discontinuation, and pathological complete response (pCR) were collected and contextualized against trial outcomes. Results: Among 79 patients, the pCR rate was higher than that reported in KEYNOTE-522 (77.2% vs. 64.8%). irAEs were documented in 51.9% of patients, compared with 33.5% in the trial. Permanent discontinuation due to irAEs occurred in 22.8% of patients, compared with 15.7% reported in KEYNOTE-522. Most discontinuations occurred during the neoadjuvant phase. Conclusions: Real-world patients experienced higher observed rates of low-grade irAEs and treatment discontinuation than reported in KEYNOTE-522; however, differences in study design limit direct comparison. These findings highlight the need for optimized toxicity management and further study of the impact of treatment duration on long-term outcomes.