Degree of food processing and risk of head and neck and oesophageal cancers in the European Prospective Investigation into Cancer study

Background and objectives: Evidence suggests that food processing may be associated with cancer risk. Associations between different degrees of food processing and head and neck cancer (HNC) and oesophageal cancer (OC) have not been fully explored. We aimed to investigate these associations in the European Prospective Investigation into Cancer (EPIC) cohort. Methods: EPIC recruited 521,323 adult participants across 10 European countries between 1992 and 1998. Our study included 450,111 EPIC participants, of which 814 and 409 were incident cases of HNC and OC, respectively. Food frequency questionnaires were used to obtain dietary data at baseline and the NOVA classification was used to categorise foods into four groups according to their degree of processing. We used Cox proportional hazard models to investigate associations between the consumption of unprocessed/minimally processed foods (NOVA 1), processed foods (NOVA 3) and ultra-processed foods (NOVA 4) and the risk of HNC and OC. Results: A 10% increase in the proportion of grams of ultra-processed food in the diet was associated with an increase in the risk of HNC (HR=1.16, 95%CI 1.07-1.27, events=814) and oesophageal adenocarcinoma (HR=1.25, 95%CI 1.06-1.48, events=215). Among HNC subtypes, a strong positive association was found for pharynx cancer (HR=1.25, 95%CI 1.09-1.44, events=264) and larynx cancer (HR=1.20, 95%CI 1.04-1.38, events=310), but not for oral cancer (HR=0.97, 95%CI 0.81-1.15, events=277). Similarly, a 10% increase in the proportion of processed food was associated with a higher risk of HNC (HR=1.26, 95%CI 1.19-1.34; pharynx cancer HR=1.23, 95%CI 1.10-1.37; larynx cancer HR=1.23, 95%CI 1.12-1.35; oral cancer HR=1.30, 95%CI 1.17-1.45) and oesophageal squamous cell carcinoma (SCC) (HR=1.77, 95%CI 1.58-1.98, events=194). In contrast, a 10% increase in the proportion of unprocessed/minimally processed food was associated with a lower risk of HNC (HR=0.73, 95%CI 0.69-0.78; pharynx cancer HR=0.77, 95%CI 0.70-0.85; larynx cancer HR=0.77, 95%CI 0.71-0.85; oral cancer HR=0.82, 95%CI 0.74-0.91) and oesophageal SCC (HR=0.66, 95%CI 0.59-0.74). Conclusions: Reducing the intake of processed and ultra-processed foods in favour of unprocessed/minimally processed foods may confer protection against HNC and OC. Further research is required to uncover the mechanisms underlying our findings.