Association of Total Flavonoid and Flavonoid Subclass Intake With Cancer-Related and All-Cause Mortality Among Cancer Patients.

Flavonoids remain controversial regarding their role in cancer-related mortality and all-cause mortality in cancer patients. A comprehensive search was conducted on Web of Science, PubMed, and CINAHL up to February 2024. Using adjusted hazard ratios (HRs), we compared flavonoid intake in the highest with lowest categories. Random-effects models were employed when the I² statistic surpassed 50%, while fixed-effects models were utilized otherwise. Fifteen eligible articles, comprising 19 cohorts, met the inclusion criteria. A significant inverse association was observed between total flavonoid intake and all-cause mortality (HR: 0.95, 95% CI: 0.91-0.99). However, the study found no significant association between total flavonoid intake and reduced cancer-related mortality risk (HR: 0.93, 95% CI: 0.83-1.04). A meta-regression analysis showed that the hazard ratio significantly decreased with the duration of follow-up (p = 0.005). Among flavonoid subclasses, flavan-3-ols intake was linked to a reduced risk of cancer-related mortality (HR: 0.74, 95% CI: 0.59-0.94). The consumption of flavanones, flavones, and isoflavones was correlated with a reduced likelihood of mortality from any cause, with summary HRs of 0.97 (95% CI: 0.95-0.99), 0.95 (95% CI: 0.92-0.98), and 0.88 (95% CI: 0.80-0.97), respectively. This study indicated that dietary intake of total flavonoids, flavanones, flavones, and isoflavones is inversely correlated with the risk of all-cause mortality in cancer patients.