Two or three year disease-free survival (DFS) as a primary end-point in stage III adjuvant colon cancer trials with fluoropyrimidines with or without oxaliplatin or irinotecan: Data from 12,676 patients from MOSAIC, X-ACT, PETACC-3, C-06, C-07 and C89803

In recent trials of cytotoxic chemotherapy, 2 or 3 years DFS HRs are highly predictive of 5 and 6 years OS HRs in stage III but not stage II patients. In all patients the DFS/OS association is stronger for 6 year OS, thus at least 6 year follow-up is recommended to assess OS benefit. These data support DFS as the primary end-point for stage III colon cancer trials testing cytotoxic agents.