Plant-Based Diet and Survival Among Patients with Metastatic Colorectal Cancer

A plant-based diet is associated with better survival among patients with nonmetastatic colorectal cancer (CRC), but its association in metastatic CRC is unknown.
Using an National Cancer Institute-sponsored trial (CALGB/SWOG 80405), we included 1284 patients who completed validated food frequency questionnaires at the initiation of metastatic CRC treatment. We calculated 3 indices: overall plant-based diet index (PDI), which emphasized consumption of all plant foods while reducing animal food intake; healthful plant-based diet index (hPDI), which emphasized consumption of healthful plant foods such as whole grains, fruits, and vegetables; and unhealthful plant-based diet index (uPDI), which emphasized consumption of less healthful plant foods such as fruit juices, refined grains, and sugar-sweetened beverages. We estimated the associations of 3 indices (quintiles) with overall survival (OS) and progression-free survival (PFS) using multivariable Cox proportional hazards regression.
We observed 1100 deaths and 1204 progression events (median follow-up = 6.1?years). Compared with the lowest quintile, patients in the highest quintile of PDI had significantly better survival (hazard ratio [HR] for OS = 0.76 [0.62-0.94], Ptrend?=?.004; PFS = 0.81 [0.66-0.99], Ptrend?=?.09). Similar findings were observed for hPDI (HR for OS = 0.81 [0.65-1.01], Ptrend?=?.053; PFS = 0.80 [0.65-0.98], Ptrend?=?.04), whereas uPDI was not associated with worse survival (HR for OS = 1.16 [0.94-1.43], Ptrend?=?.21; PFS = 1.12 [0.92-1.36], Ptrend?=?.42).
Our study suggests that a plant-based diet, especially when rich in healthful plant foods, is associated with better survival among patients with metastatic CRC. The cause of survival benefits warrants further investigation.

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