The causes for hypothyroidism in cancer patient may not only be associated with tumor necrosis factor, interleukin-1, interferon-γ [17,18], which inhibits the function of hypothalamus-pituitary-thyroid axis and peripheral conversion of T4 to T3, but also be associated with the self-protection mechanism, reducing the tissue metabolism to suppress the tumor growth. This evidence concerns the gene TNF and neoplasm.