Interleukin-2-induced thyroid dysfunction is correlated with treatment duration but not with tumor response

Purpose: To analyze the putative relationship between immunotherapy-associated dysthyroidism and the probability of a tumor response. Patients and Methods: A total of 89 consecutive patients with advanced cancer were treated with interleukin-2 (IL2)-based immunotherapy in a prospective study. Results: Twenty patients developed thyroid dysfunction. Repeatedly positive tests for thyroid antibodies developed in 28% of the patients. Twenty-two patients achieved a response. There was no relationship between the formation of antibodies and the probability of response. There appeared to be a trend toward a relationship between thyroid dysfunction and response (P = .23). A strong relationship was found between re-sponse on the one hand and cumulative dose of IL2 (P = .01) and treatment duration with IL2 (P = .025) on the other. The frequency of thyroid dysfunction was also significantly correlated with treatment duration (P = .001). After adjustment for cumulative dose of IL2 and treatment duration, no relationship between thyroid dysfunction and response remained (P = .99). Conclusion: There is no relationship between thyroid dysfunction and the probability of tumor response. Thyroid dysfunction is merely a function of treatment duration and cumulative dose of IL2.