Purpose

To evaluate the role of metformin on thyroid cancer risk in patients with acromegaly.

Methods

Medical charts of 534 patients with acromegaly that were followed-up between 1983 and 2019 were reviewed. Patients with follow-up duration at least 6 months were included. Cohort entry was defined as first visit date. The date of each case's thyroid cancer diagnosis was defined as index date. Patients were followed until the index date, death, or last visit date, whichever came first. Nested case-control study design was selected to evaluate the association between metformin and the thyroid cancer risk in patients with acromegaly.

Results

291 patients with acromegaly were included into final analysis. The mean age at acromegaly diagnosis was 42.3 ± 1.3 years. The median follow-up duration was 76 [34–132] months. Among 291 patients, 13 patients (4.5%) had thyroid cancer. Thirty-one percent (n = 92) of the patients used metformin for 6 months or longer. One standard deviation (SD) increase in average growth hormone increased the odds of having thyroid cancer by 1.164 folds (p = 0.017). One SD increase of the average insulin-like growth factor 1 to upper limit of normal ratio increased the odds of having thyroid cancer by 1.201 folds (p = 0.004). If a patient used metformin for at least 6 months, the odds to have thyroid cancer was decreased, multiplied by 0.62 with a 95% confidence interval of [0.47, 0.83] (p = 0.0013). The risk of thyroid cancer decreased with increasing duration of metformin use.

Conclusion

Metformin may decrease the thyroid cancer risk in patients with acromegaly.

中文翻译：

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二甲双胍对肢端肥大症患者甲状腺癌风险的影响：初步观察性研究

目的

评估二甲双胍对肢端肥大症患者患甲状腺癌风险的作用。

方法

回顾了 1983 年至 2019 年间随访的 534 名肢端肥大症患者的医疗图表。随访时间至少 6 个月的患者被纳入。队列条目定义为首次访问日期。每个病例的甲状腺癌诊断日期被定义为索引日期。对患者进行随访直至索引日期、死亡或最后一次就诊日期（以先到者为准）。选择巢式病例对照研究设计来评估二甲双胍与肢端肥大症患者甲状腺癌风险之间的关联。

结果

291例肢端肥大症患者纳入最终分析。诊断肢端肥大症的平均年龄为 42.3 ± 1.3 岁。中位随访时间为 76 [34-132] 个月。在 291 名患者中，13 名患者（4.5%）患有甲状腺癌。百分之三十一 ( n  = 92) 的患者使用二甲双胍 6 个月或更长时间。平均生长激素水平每增加一个标准差 (SD)，患甲状腺癌的几率就会增加 1.164 倍 ( p  = 0.017)。平均胰岛素样生长因子 1 增加 1 个标准差至正常比例上限，患甲状腺癌的几率就会增加 1.201 倍 ( p  = 0.004)。如果患者使用二甲双胍至少 6 个月，患甲状腺癌的几率会降低，乘以 0.62，95% 置信区间为 [0.47, 0.83] (p = 0.0013 )  。甲状腺癌的风险随着二甲双胍使用时间的增加而降低。

结论

二甲双胍可以降低肢端肥大症患者患甲状腺癌的风险。