Dietary flavonoids, lignans and colorectal cancer prognosis

Flavonoids and lignans are polyphenol classes with anticarcinogenic activities against colorectal cancer (CRC). However, very limited epidemiological evidence exists on their effects on CRC prognosis. This study aimed to evaluate the association between flavonoid and lignan intakes with the risk of CRC recurrence and overall survival in CRC patients. The study followed incident histologically confirmed CRC cases in Barcelona (Spain). Validated dietary questionnaires and lifestyle information were collected at recruitment. An ad hoc food composition database on flavonoids and lignans was compiled by using data from the US Department of Agriculture and Phenol-Explorer databases. Adjusted hazards ratios (HR) and 95% confidence intervals (CIs) were estimated using multivariable Cox models. After 8.6 years of mean follow-up, 133 of 409 (32.5%) participants died and 77 of 319 (24.1%) had a CRC recurrence. Total flavonoids were associated neither with CRC recurrence (HR comparing extreme tertiles 1.13, 95% CI 0.64–2.02; P-trend 0.67) nor with overall survival (HR(T3vsT1) 1.06, 95% CI 0.69–1.65; P-trend 0.78) in the multivariable models. No associations were also observed with either total lignans or any flavonoid subclass intake. In conclusion, the results of the current study do not support a role of flavonoid and lignan intake in the CRC prognosis.