The authors review the most common situation concerning oncological patients with concomitant thyroid
disease. In case of unknown origin of metastasis and nodular goitre the ultrasound examination with fine needle
aspiration biopsy confirms or excludes the thyroid origin. The euthyroid sick syndrome is often diagnosed in
oncological patient as a consequence of oncological disease and it doesn’t mean hypothyroidism. If oncological
patients prove to have a thyroid functional failure the endocrinologist must correct the function as fast as
possible to enable oncological treatment. There is no evidence that chemotherapy can influence the thyroid
function, but radiotherapy can cause thyroiditis with later hypofunction. The interferon therapy causes thyroid
dysfunction in l0% of patients and the recommendation to examine not only TSH and FT4 but also thyroid
antibodies is warranted. Lymphoma of the thyroid gland occurs most often on the basis of lymphocytic
thyroiditis and lymphocytic thyroiditis may be a risk factor for papillary carcinoma of the thyroid as well.
Women with breast carcinoma were proved to have lymphocytic thyroiditis with minor thyroid hypofunction
more often than the corresponding group of women with colon cancer or control group of healthy women. In
case of renal tumor (Grawitz), breast or lung carcinoma the thyroid can be attacked with metastasis, and
ultrasound with fine needle biopsy can reliably differentiate between primary or secondary thyroid
involvements. The thyroid can be involved in some diseases: multiple endocrine neoplasia, Carney, Cowden and
thyroid, hypothyroidism, hyperthyroidism, breast carcinoma, lymphoma, cytokins.