Loyola University School of Medicine, Chicago, USA.
Reprod Biol Endocrinol. 2013 Aug 8;11:75. doi: 10.1186/1477-7827-11-75.
Levothyroxine (LT4) treatment can lead to iatrogenic hyperthyroidism and oxidative stress that can cause patient discomfort. Oxidative stress is also recognized as one of the causes of chronic diseases and cancer.
The prevalence of breast, colorectal, gastric and lung cancer in 18 Italian Regions during 2010 was correlated with the sales of LT4 in 2009. The cancer prevalence was analyzed in women aged 30-84. This age range corresponds to more than 80% of the consumers of the drug and to about 99% of all malignant cancers. The correlation between sales of LT4 and cancers was determined with the technique of Density Ellipses. The age and smoking contribution for lung cancer was determined with the Sequential test.
No significant correlation was seen between LT4 sales and breast, colorectal and gastric cancers. A significant correlation was instead found for lung cancer (p<0.05) corrected for smoking and age.
LT4 consumption in Italy is about 0.7 boxes/women/year. There is a correlation between lung cancer and LT4 treatment and oxidative stress caused by LT4 supplementation can be one of the causes. Although we cannot exclude that dysthyroidism needing LT4 supplementation might be the ground for lung cancer itself and measuring oxidative stress could be helpful in avoiding excessive use of the drug.
左甲状腺素（LT4）治疗可导致医源性甲状腺功能亢进和氧化应激，从而导致患者不适。氧化应激也被认为是慢性病和癌症的原因之一。
2010 年，意大利 18 个地区的乳腺癌、结直肠癌、胃癌和肺癌的患病率与 2009 年 LT4 的销售额相关联。分析了 30-84 岁女性的癌症患病率。这个年龄范围超过了 80%的药物消费者，占所有恶性癌症的 99%左右。用密度椭圆技术确定 LT4 销售与癌症之间的相关性。用序贯检验确定肺癌的年龄和吸烟贡献。
LT4 销售与乳腺癌、结直肠癌和胃癌无显著相关性。然而，肺癌（p<0.05）与 LT4 治疗和 LT4 补充引起的氧化应激之间存在显著相关性，且校正了吸烟和年龄因素。
意大利 LT4 的消耗量约为 0.7 盒/女性/年。肺癌与 LT4 治疗之间存在相关性，LT4 补充引起的氧化应激可能是其原因之一。尽管我们不能排除需要 LT4 补充的甲状腺功能减退症可能是肺癌本身的基础，而且测量氧化应激可能有助于避免过度使用该药物。
