Thyroid dysfunction associated with immunotherapy for patients with cancer

The authors performed a prospective study to evaluate thyroid dysfunction in 130 patients with cancer who were receiving interleukin‐2 (IL‐2)‐based immunotherapy. Primary hypothyroidism was the most common abnormality, occurring in 12% of patients before, 38% during, and 23% after immunotherapy. Hyperthyroidism occurred in 1%, 4%, and 7% of patients at those time intervals. Among patients initially euthyroid (n = 111), primary hypothyroidism developed in 32% during and 14% after immunotherapy, persisting a median of 54 days. Three patients required levothyroxine. Hyperthyroidism developed in 2% of patients during immunotherapy and 6% after. Thyroid dysfunction was not a function of sex, diagnosis, type of treatment, or response to immunotherapy. Elevated titers of antithyroglobulin and antithyroid microsomal antibodies were detected after treatment in 9% and 7%, respectively, of all patients without prior antibody abnormalities and did not correlate with response to therapy. The high incidence of therapy‐induced thyroid dysfunction suggests that thyroid function should be carefully monitored in all patients receiving IL‐2‐based immunotherapy. Cancer 68:2384–2390, 1991.