Results from a large, prospective cohort study show that eating a less inflammatory diet may reduce the risk of death for patients with stage III colon cancer. The research was presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting.

"One of the most common questions that patients ask is what diet they should be following to maximally reduce their risk of cancer recurrence and improve survival. While there have been many studies examining dietary factors and the risk of developing colorectal cancer, there is significantly less known about how diet impacts colon cancer outcomes after diagnosis. This study sheds light on the relationship between dietary patterns and survival in patients with stage III colon cancer,” said lead study author Sara K. Char, MD, Dana-Farber Cancer Institute in Boston, Massachusetts.

To assess the effects of diet on the risk of colon cancer recurrence, the diet habits of a subset of patients enrolled in the phase 3 CALGB/SWOG 80702 clinical trial were analysed in a prospective cohort study.

The CALGB/SWOG 80702 clinical trial tested 3 months vs. 6 months of adjuvant chemotherapy, with or without celecoxib, an anti-inflammatory medication. A prospective cohort study follows patients with similar characteristics who differ in a key factor over time to see if that factor impacts outcomes.

Of the approximately 2,500 patients enrolled in CALGB/SWOG 80702, there were 1,625 patients followed as part of this study. The patients all had stage III colon cancer that had been removed with surgery. The average age of the participants was 60.9 years. The patients reported their diet and exercise habits at six weeks after being randomly assigned to a treatment group in the CALGB/SWOG 80702 study and again 14 to 16 months after random assignment. Their diets were scored using the empirical dietary inflammatory pattern (EDIP) tool.

The EDIP tool is a weighted sum of 18 food groups: 9 pro-inflammatory and 9 anti-inflammatory. Examples of pro-inflammatory foods include red meat, processed meats, refined grains and sugary drinks. Examples of anti-inflammatory foods include coffee, tea, dark yellow vegetables and leafy green vegetables. A high EDIP score indicates a pro-inflammatory diet. A low EDIP score represents a less inflammatory diet.

Key Findings

• Patients who consumed the most pro-inflammatory diets and had the highest EDIP scores were:

                       - More likely to be younger (average age 58.7 vs. 61.3)

                        - More likely to be female (64% vs. 48.9%)

                        - Have an ECOG score of 1 or 2, indicating a lesser ability to perform daily activities (35.7% vs.19.4%)

                        - Less likely to be White (76.6% vs. 92.0%)

                        - More likely to be Black (15.4% vs. 3.7%)

• Pro-inflammatory diets were associated with worse outcomes. Patients with the highest EDIP scores and very pro-inflammatory diets had an 87% higher risk of death than those who ate highly anti-inflammatory diets.
• Exercise habits, another modifiable factor associated with systemic inflammation, also impacted overall survival. Patients who consumed less inflammatory diets and exercised more often (9 or more metabolic equivalent [MET] hours per week) had the best overall survival, with 63% lower risk of death compared to patients who ate pro-inflammatory diets and exercised less (less than 9 MET hours per week).
• There was no significant difference in disease-free survival between the patients who ate a pro-inflammatory diet and those who ate an anti-inflammatory diet.
• Low-dose aspirin use and which treatment regimen the patients received as part of the CALGB/SWOG 80702 trial were not significantly different between the groups.

“This early but promising observational study suggests a powerful synergy: Patients with stage III colon cancer who embraced anti-inflammatory foods and exercised regularly showed the best overall survival compared to those with inflammatory diets and limited exercise,” said Julie R. Gralow, MD, FACP, FASCO, ASCO Chief Medical Officer and Executive Vice President.

Researchers will continue to study how diet and inflammation, as well as exercise, affect outcomes for patients with colorectal cancer.

Source: ASCO