Importance: The American Cancer Society and American Institute for Cancer Research recommend that cancer survivors limit intake of red and processed meats. This recommendation is based on consistent associations between red and processed meat intake and cancer risk, particularly risk of colorectal cancer, but fewer data are available on red and processed meat intake after cancer diagnosis.

Objectives: To examine whether intake of unprocessed red meat or processed meat is associated with risk of cancer recurrence or mortality in patients with colon cancer.

Design, Setting, and Participants: This prospective cohort study used data from participants with stage III colon cancer enrolled in the Cancer and Leukemia Group B (CALGB 89803/Alliance) trial between 1999 and 2001. The clinical database for this analysis was frozen on November 9, 2009; the current data analyses were finalized in December 2021.

Exposures: Quartiles of unprocessed red meat and processed meat intake assessed using a validated food frequency questionnaire during and 6 months after chemotherapy.

Main Outcomes and Measures: Hazard ratios (HRs) and 95% CIs for risk of cancer recurrence or death and all-cause mortality.

Results: This study was conducted among 1011 patients with stage III colon cancer. The median (IQR) age at enrollment was 60 (51-69) years, 442 patients (44%) were women, and 899 patients (89%) were White. Over a median (IQR) follow-up period of 6.6 (1.9-7.5) years, we observed 305 deaths and 81 recurrences without death during follow-up (386 events combined). Intake of unprocessed red meat or processed meat after colon cancer diagnosis was not associated with risk of recurrence or mortality. The multivariable HRs comparing the highest vs lowest quartiles for cancer recurrence or death were 0.84 (95% CI, 0.58-1.23) for unprocessed red meat and 1.05 (95% CI, 0.75-1.47) for processed meat. For all-cause mortality, the corresponding HRs were 0.71 (95% CI, 0.47-1.07) for unprocessed red meat and 1.04 (95% CI, 0.72-1.51) for processed meat.

Conclusions and Relevance: In this cohort study, postdiagnosis intake of unprocessed red meat or processed meat was not associated with risk of recurrence or death among patients with stage III colon cancer.