Background: Oxaliplatin-based adjuvant therapy is the standard of care for stage III colon cancer; however, its impact on PRS in these patients is unclear. We therefore compared PRS in trials of patients with stage III colon cancer treated with oxaliplatin plus capecitabine (XELOX) or 5-flourouracil (5-FU; FOLFOX) vs. leucovorin/5-FU (LV/5-FU). Methods: Individual patientdata (N = 4,819) from NSABP C-08, XELOXA, X-ACT, and AVANT were pooled and analyzed by XELOX/FOLFOX vs. LV/5-FU; patients treated with bevacizumab were excluded. Hazard ratios (HR) were estimated by Cox regression analyses and multivariate Cox regression analyses controlled for age, gender, T, and N stage. Post-relapse treatment data were collected when available. Results: Patient demographics and disease characteristics (except lymph nodes examined) were well balanced across analytic groups. Median follow-up was shorter in NSABP C-08 and AVANT (36 and 50 months) than in XELOXA and X-ACT (83 and 74 months). PRS was very similar for XELOX/FOLFOX and LV/5-FU (HR 0.94, 95% CI, 0.82–1.07; P = .33). Multivariate analyses supported these findings, but showed that PRS was associated with younger age and lower N stage at diagnosis after controlling for gender and T stage. PRS was also comparable for capecitabine or XELOX vs. LV/5-FU or FOLFOX (N = 5,819, HR 1.07, 95% CI, 0.95–1.20; P = .26). Post-relapse therapies were comparable across the two cohorts. Conclusions: Adjuvant chemotherapy regimen did not impact on PRS in patients with stage III colon cancer; however, both N stage and age demonstrated independent effects on PRS. Studies have demonstrated significantly improved disease-free and overall survival for oxaliplatin-based therapy, and our data show that survival is not compromised by worsened PRS at subsequent relapse.

Multivariate analysis	PRS HR	95% CI	P
Randomized treatment: XELOX/FOLFOX vs. LV/5-FU	0.92	0.81–1.05	.23
Female vs. male	1.02	0.90–1.16	.71
< 70 vs. ≥ 70	0.70	0.60–0.81	< .0001
T1–2 vs. T3–4	0.82	0.61–1.10	.19
N1 vs. N2	0.73	0.64–0.83	< .0001