Researchers from the M. D. Anderson Cancer Center have reported that long-term hypothyroidism in women significantly increases the risk of developing hepatocellular carcinoma. The details of this study appeared in the May 2009 issue of Hepatology.[1]

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. Factors that increase the risk of developing HCC include long-term, heavy alcohol use and chronic infection with hepatitis B or C viruses. Although not common in the United States, hepatocellular carcinoma is the third leading cause of cancer deaths worldwide. The disease appears to be on the rise, possibly due to an increased incidence of the hepatitis B and C viruses. A recent report suggests that incidence of liver cancer in the United States tripled between 1975 and 2005.

There is some evidence of a link between thyroid disease and hepatitis C virus. In addition, there is evidence that hypothyroidism is related to inflammation of the liver cells. However, no clear link has been established between hypothyroidism and liver cancer.

Researchers conducted a study to compare the incidence of HCC among patients with and without hypothyroidism. The study included 420 patients with HCC and 1,104 healthy control subjects. The researchers found that a long-term history of hypothyroidism (10 or more years) was associated with a statistically significant high risk of HCC in women—specifically, they were 2.9 times more likely to develop HCC than women without thyroid disease.

Hypothyroidism did not appear to increase the risk of HCC for men. Hyperthyroidism did not increase the risk of HCC in either sex.

Comments: These researchers concluded that women with long-term hypothyroidism are at an increased risk of developing HCC. It is unclear whether the weight gain often associated with hypothyroidism plays a role in the development of HCC, as hypothyroidism that did not result in weight gain also appeared to contribute to the development of HCC. Research will likely be ongoing to continue to evaluate this link.

Reference:

[1] Hassan MM, Kaseb A, Li D, et al. Association between hypothyroidism and hepatocellular carcinoma: A case-control study in the United States. Hepatology. 2009; 49: 1563-1570.