The effect of nutritional habits and addictions on the incidence of thyroid carcinoma in the Olsztyn province of Poland.

INTRODUCTION The aim of this study was to investigate the roles of nutritional habits and addictions in the incidence of thyroid carcinoma. MATERIAL AND METHODS The study of risk factors affecting the incidence of thyroid carcinoma was conducted in patients included in a register of thyroid carcinoma. For that purpose, a questionnaire was prepared. The questionnaire covered: personal information, medical history, individual risk factors of thyroid carcinoma such as nutritional habits, alcohol consumption and smoking. Statistical analysis was conducted. RESULTS The register comprised 297 patients with thyroid carcinoma (89% women) and 589 healthy subjects. 46% of patients declared frequent consumption of milk and dairy products. The patients with thyroid carcinoma consumed cruciferous plants significantly more often than healthy subjects (p = 0.0001) whereas egg consumption among both groups of patients was similar. Low consumption of fish and average table salt consumption was typical of both groups. Alcohol consumption was similar in both groups and was, respectively, 42.18% and 47.59%. The patients with thyroid cancer smoked less frequently than subjects from the control group. Logistic regression analysis showed that carcinoma risk increased in patients who consumed cruciferous vegetables (brassicas). Their regular intake was related to a 1.5-fold (CI 1.19-1.96) higher risk of thyroid carcinoma incidence. Despite the demonstrated decreased risk of thyroid cancer, smoking (OR 0.54) was not considered a protective factor. CONCLUSIONS 1. It is not possible to determine unequivocally the causative factors for the growth in the incidence of thyroid cancer in Olsztyn province. 2. It appears that one of the environmental factors causing the increase is overconsumption of cruciferous vegetables.