Association between dietary habits and incident thyroid cancer: A prospective cohort study

Abstract

BackgroundIn addition to the thyroid cancer (TC) risk from lifestyle and environmental factors such as radiation exposure, some studies have indicated that diet may affect TC development; however, previous findings are inconsistent. The objective of our study was to investigate the association between dietary habits and TC risk in a Korean population.Materials and methodsA total of 13,973 participants were selected after excluding ineligible subjects from the Cancer Screenee Cohort at National Cancer Center in Korea from October 2007 to December 2021. Participants were followed until May 2022 to identify incident TC cases. Information on dietary habits and general characteristics was collected using a self-report questionnaire administered at enrollment without keeping track of changes in eating habits during the follow-up period. A Cox proportional hazards model was used to determine the hazard ratio (HR) and 95% confidence interval (CI) of TC risk for each dietary factor.ResultsA total of 138 incident TC cases were identified during the median follow-up period of 7.6 years. Of the 12 dietary habits evaluated, only two habits showed significant associations with TC. A significantly decreased TC risk was found among participants who consumed milk and/or dairy products 5 or more days a week [adjusted HR (aHR), 0.58; 95% CI, 0.39–0.85]. Notably, a stronger protective effect of dairy consumption was observed in participants aged ≥ 50 years (aHR, 0.44; 95% CI, 0.26–0.75), in women (aHR, 0.53; 95% CI, 0.35–0.81), and in non-smokers (aHR, 0.60; 95% CI, 0.39–0.92). There was a reduced risk of TC in participants with meal durations longer than 10 min (aHR, 0.58; 95% CI, 0.41–0.83). However, this association was limited to individuals aged ≥ 50 years (aHR, 0.49; 95% CI, 0.31–0.79), women (aHR, 0.61; 95% CI, 0.41–0.90), and non-smokers (aHR, 0.62; 95% CI, 0.41–0.92).ConclusionOur findings suggest that consuming milk and/or dairy products 5 or more days a week and having a meal duration longer than 10 min could be protective factors against TC, especially in individuals aged ≥ 50 years, women and non-smokers. Further prospective studies are needed to investigate the association of dietary intake with specific types of TC.

Association between Consumption of Iodine-Rich Foods and Thyroid Cancer Prevalence: Findings from a Large Population-Based Study

“…However, a Japanese cohort study and an Italian case-control study have suggested that individuals with higher dairy intake had a lower TC risk [30,32]. A recent National Cancer Center survey in Korea discovered that consuming milk and dairy products more than 5 times/week is associated with a reduced risk of TC [8]. Our study identified a reverse J-shaped relationship with dairy consumption, aligning with previous research and showing an increased TC risk when consuming too few dairy products.…”

“…Our study comprehensively evaluated 106 food items, including 337 foods that majorly contribute to 17 nutrients, including seasonal items, and was conducted by trained interviewers. In contrast, a prior National Cancer Center study utilized a dietary habit questionnaire consisting of only 12 items, potentially lacking a comprehensive assessment of all food items influencing TC development [8]. Confirmation of our findings will necessitate future studies, and investigating and considering specific dairy products, such as milk and butter, in more detail is essential.…”

“…Vitamin D can protect against tumors by binding to vitamin D receptors on TC cells, inhibiting their growth and impeding TC development [29]. Currently, the influence of dairy food intake on TC occurrence remains controversial [8,30,31]. A population-based case-control study conducted in two regions of Sweden and Norway reported that high cheese and butter intake is associated with higher TC risk [31].…”

“…Numerous studies have sought to elucidate the link between diet and TC [6][7][8]. Specific evidence suggests that dietary patterns and the risks associated with certain nutrients, such as iodine, could influence the modulation of TC risk [9,10].…”

“…The influence of geographical, socioeconomic, ethnic, and cultural factors must be considered in studying TC risk factors [4,5]. Additionally, the complexities of the relationship between dietary consumption and TC occurrence should be considered, as this relationship is influenced by the presence of various bioactive compounds in foods, aside from the multifaceted effects of iodine [6][7][8].…”