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Background: Alcohol and tobacco are the major risk factors for oral and pharyngeal cancer, but diet is likely to have a role, too. Objective: The objective was to analyze the relationship between adherence to the 2015-2020 Dietary Guidelines for Americans (DGA), as measured by the Healthy Eating Index 2015 (HEI-2015), and oral and pharyngeal cancer risk. Moreover, this work aimed to quantify the number of avoidable cases under different scenarios of increased adherence to the DGA, with the use of the potential impact fraction. This estimates the proportion of cases that would occur if the distribution of the risk factor in the population followed an alternative distribution. Design: A multicenter, case–control study was conducted in Italy between 1991 and 2009. Participants’ usual diet for the 2 years preceding study enrolment was assessed using a food frequency questionnaire. Participants and setting: Cases were 946 patients admitted to major hospitals with incident, histologically confirmed oral and pharyngeal cancer. Controls were 2,492 patients admitted to the same hospitals for acute non neoplastic conditions. Main outcome measures: The adherence to the DGA was assessed using the HEI-2015 score (range = 0 to 100), based on 13 components. The outcome was oral and pharyngeal cancer. Statistical analyses performed: Odds ratios and the corresponding 95% CIs were estimated using multiple logistic regression models adjusted for tobacco, alcohol, and other relevant covariates. The potential impact fraction was estimated under different scenarios of adherence to the DGA. Results: In this Italian population the HEI-2015 score ranged from 33.4 to 97.5. A higher HEI-2015 score was associated with a lower risk of oral and pharyngeal cancer, with an odds ratio of 0.70 (95% CI 0.62 to 0.79) for a 10-point increment of the score. The estimated potential impact fraction was 64.8% under the maximum achievable reduction scenario, and it ranged from 9% to 27% following other more

Flavonoids have been inversely associated to colorectal cancer (CRC) and are plausible intermediaries for the relation among gut microbiome, intestinal permeability and CRC. We analyzed the relation of flavonoid intake with CRC and blood bacterial DNA. We conducted a case–control study in Italy involving 100 incident CRC cases and 200 controls. A valid and reproducible food–frequency questionnaire was used to assess dietary habits and to estimate six flavonoid subclass intakes. We applied qPCR and 16S rRNA gene profiling to assess blood bacterial DNA. We used multiple logistic regression to derive odds ratios (ORs) of CRC and Mann–Whitney and chi-–square tests to evaluate abundance and prevalence of operational taxonomic units (OTUs) according to flavonoid intakes. Inverse associations with CRC were found for anthocyanidins (OR for the highest versus the lowest tertile = 0.24, 95% confidence interval, CI = 0.11–0.52) and flavanones (OR = 0.18, 95% CI = 0.08–0.42). We found different abundance and prevalence according to anthocyanidin and flavanone intake for OTUs referring to Oligoflexales order, Diplorickettsiaceae family, Staphylococcus, Brevundimonas, Pelomonas and Escherischia–Shigella genera, and Flavobacterium and Legionella species. The study provides evidence to a protective effect of dietary anthocyanidins and flavanones on CRC and suggests an influence of flavonoids on blood bacterial DNA, possibly through intestinal permeability changes.

High dietary glycaemic index (GI) and glycaemic load (GL) may increase cancer risk. However, limited information was available on GI and/or GL and head and neck cancer (HNC) risk. We conducted a pooled analysis on 8 case-control studies (4081 HNC cases; 7407 controls) from the International Head and Neck Cancer Epidemiology (INHANCE) consortium. We estimated the odds ratios (ORs) and 95% confidence intervals (CIs) of HNC, and its subsites, from fixed- or mixed-effects logistic models including centre-specific quartiles of GI or GL. GI, but not GL, had a weak positive association with HNC (ORQ4 vs. Q1 = 1.16; 95% CI = 1.02–1.31). In subsites, we found a positive association between GI and laryngeal cancer (ORQ4 vs. Q1 = 1.60; 95% CI = 1.30–1.96) and an inverse association between GL and oropharyngeal cancer (ORQ4 vs. Q1 = 0.78; 95% CI = 0.63–0.97). This pooled analysis indicates a modest positive association between GI and HNC, mainly driven by laryngeal cancer.

The possible role of dietary fiber in the etiology of head neck cancers (HNCs) is unclear. We used individual-level pooled data from ten case-control studies (5959 cases and 12,248 controls) participating in the International Head and Neck Cancer Epidemiology (INHANCE) consortium, to examine the association between fiber intake and cancer of the oral cavity/pharynx and larynx. Odds Ratios (ORs) and their 95% Confidence Intervals (CIs) were estimated using unconditional multiple logistic regression applied to quintile categories of non-alcohol energy-adjusted fiber intake and adjusted for tobacco and alcohol use and other known or putative confounders. Fiber intake was inversely associated with oral and pharyngeal cancer combined (OR for 5th vs. 1st quintile category = 0.49, 95% CI: 0.40–0.59; p for trend <0.001) and with laryngeal cancer (OR = 0.66, 95% CI: 0.54–0.82, p for trend <0.001). There was, however, appreciable heterogeneity of the estimated effect across studies for oral and pharyngeal cancer combined. Nonetheless, inverse associations were consistently observed for the subsites of oral and pharyngeal cancers and within most strata of the considered covariates, for both cancer sites. Our findings from a multicenter large-scale pooled analysis suggest that, although in the presence of between-study heterogeneity, a greater intake of fiber may lower HNC risk.