Levothyroxine and lung cancer in females: the importance of oxidative stress
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RESEARCH
Open Access
Levothyroxine and lung cancer in females: the importance of oxidative stress Umberto Cornelli1, Gianni Belcaro2, Martino Recchia3 and Annarosa Finco4*
Abstract Background: 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. Methods: 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. Results: 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. Conclusions: 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. Keywords: Levothyroxine, Smoking, Oxidative stress, Lung cancer, Dysthyroidism
Background During studies aimed at assessing the relationship between food intake and metabolic syndrome in Italy, a large number of subjects was found to use levothyroxine (LT4) for hypothyroidism. A survey conducted in USA on the intake of thyroid supplements [1] found that side effects may occur in as many as 20% of treated cases, the most common being palpitation, sweating, agitation/anxiety and daily discomfort which are typical symptoms of iatrogenic hyperthyroidism. A clinical study indicated that these side effects were correlated with the increase of plasma hydroperoxides which are markers of oxidative stress [2], and the use of a pool of physiological modulators (PMs) with antioxidant activity was found effective in reducing all these side effects [3].
* Correspondence: [email protected] 4 Cor Con International-Ox Res Dept, Parma(PR), Italy Full list of author information is available at the end of the article
These findings suggest that the chronic use of LT4 is consistent with an overproduction of reactive oxygen species (ROS) caused by the hypermetabolic status provoked by administration of this hormone [4-6]. Achievement of euthyroid status is monitored by measuring TSH, T3 and T4 plasma levels, mainly in the morning on a empty stomach, a few times in a year, but measuring oxidative stress was never considered a useful tool for adjusting LT4 doses. The LT4 administration leads to T4 and T3 peak be
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