Consumption of salt and high-salt foods and the risks of oral, pharyngeal and oesophageal cancers: the JACC Study.

The association between salt and salted food consumption and oral, pharyngeal and oesophageal cancers remains inconclusive. To address this, we conducted a large-scale nationwide cohort study in Japan, a region globally recognised for its high-salt consumption. In a baseline survey conducted from 1988 to 1990, salt consumption was evaluated using a self-administered FFQ in a sample of 42 535 participants aged 40-79 years. Over a median 14·4-year follow-up period, 145 incident cases of oral (n 43), pharyngeal (n 17) and oesophageal (n 85) cancers were observed. A Cox proportional hazards model was used to estimate the hazard ratio (HR) and 95 % CI after adjusting for age, sex, smoking status, alcohol consumption and fruit and vegetable consumption. High-salt consumption was associated with a higher risk of oral, pharyngeal and oesophageal cancers combined; the multivariable HR for the highest v. lowest tertiles of salt consumption was 1·67 (95 % CI: 1·08, 2·61, P-trend = 0·01). An excess risk was primarily observed for oral and oesophageal cancers. Among the salt sources, miso soup consumption was positively associated with the combined risk of oral, pharyngeal and oesophageal cancers; however, the consumption of other high-salt foods was not. In conclusion, high-salt consumption was associated with a higher combined risk of oral, pharyngeal and oesophageal cancers.