CONTEXT Nonalcoholic fatty liver disease (NAFLD) is a hepatic manifestation of metabolic syndrome. Obesity and metabolic syndrome are known risk factors for thyroid cancer. OBJECTIVE We investigated the association between NAFLD and thyroid cancer risk in young adults. METHODS This nationwide cohort study included 1 135 967 participants aged 20 to 39 years who underwent 4 consecutive health screenings in South Korea. NAFLD was categorized using the fatty liver index (FLI), as follows: ≥60, 30 to 60, and <30. The cumulative FLI points were defined as the number of times participants had a FLI of ≥30 (0-4). RESULTS During a median follow-up of 5.2 years, 4126 participants (0.36%) were newly diagnosed with thyroid cancer. Compared with the participants with an FLI of <30, those with an FLI of 30 to 60 (men: hazard ratio [HR] 1.36 [95% CI, 1.22-1.51] and women: HR 1.44 [1.21-1.70]) and those with an FLI of ≥60 (men: HR 1.71 [1.53-1.92] and women: HR 1.81 [1.46-2.25]) had a significantly higher risk of thyroid cancer. Participants with higher cumulative FLI points had a higher risk of thyroid cancer compared to those with a cumulative FLI point of 0 (P < .001). During the follow-up period, the participants with an increased FLI exhibited an increased risk of thyroid cancer. CONCLUSION NAFLD was associated with an increased risk of thyroid cancer in young adults. Repeatedly elevated FLI and progression of NAFLD were associated with an increased risk of thyroid cancer in this study.

中文翻译：

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韩国年轻人非酒精性脂肪肝和甲状腺癌的风险。

背景 非酒精性脂肪性肝病 (NAFLD) 是代谢综合征的肝脏表现。肥胖和代谢综合征是甲状腺癌的已知危险因素。目的 我们调查了年轻人 NAFLD 与甲状腺癌风险之间的关联。方法 这项全国性队列研究纳入了 1 135 967 名年龄在 20 至 39 岁之间的参与者，他们在韩国连续接受了 4 次健康检查。NAFLD 使用脂肪肝指数 (FLI) 进行分类，如下：≥60、30 至 60 和 <30。累积 FLI 分数定义为参与者 FLI ≥30 (0-4) 的次数。结果 在中位随访 5.2 年期间，4126 名参与者 (0.36%) 新诊断出患有甲状腺癌。与 FLI <30 的参与者相比，FLI 为 30 至 60 的参与者（男性：风险比 [HR] 1.36 [95% CI，1.22-1.51]，女性：HR 1.44 [1.21-1.70]）和那些FLI ≥ 60（男性：HR 1.71 [1.53-1.92]，女性：HR 1.81 [1.46-2.25]）患甲状腺癌的风险显着较高。与累积 FLI 分数为 0 的参与者相比，累积 FLI 分数较高的参与者患甲状腺癌的风险较高 (P < .001)。在随访期间，FLI 增加的参与者患甲状腺癌的风险增加。结论 NAFLD 与年轻人患甲状腺癌的风险增加相关。在这项研究中，FLI 反复升高和 NAFLD 进展与甲状腺癌风险增加相关。