Abstract
PURPOSE: Quantifying the association of chemotherapy relative dose intensity (RDI) with overall survival may enable supportive care interventions that improve chemotherapy RDI to estimate their magnitude of potential clinical benefit. METHODS: This cohort study included 533 patients with stage II-III colon cancer who initiated a planned regimen of 12 cycles of 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) chemotherapy. The primary exposure was chemotherapy RDI. The primary outcome was overall survival. Restricted cubic splines estimated hazard ratios (HR). RESULTS: Chemotherapy regimen RDI was associated with overall survival in an L-shaped pattern (linear P = 0.006; nonlinear P = 0.057); the risk of death was flat above 85% but increased linearly below 85%. For example, a decrease in RDI from 85 to 75% was associated with an increased risk of death [HR: 1.20 (95% CI: 1.08, 1.52)], whereas an increase in RDI from 85 to 95% was not associated with the risk of death [HR: 1.06 (95% CI: 0.82, 1.38)]. CONCLUSION: If chemotherapy RDI is considered a potential surrogate of overall survival, supportive care interventions that improve chemotherapy RDI might confer a potential clinical benefit in this population.