Abstract
Background. Although nivolumab is applied as standard second-line chemotherapy for non-small cell lung cancer (NSCLC), it induces many immune-related adverse events (irAEs), including thyroid dysfunction. The various clinical features and pathogenesis of thyroid dysfunction induced by nivolumab are not well defined. Case 1. A 47-year-old man diagnosed with cT1bN2M1b stage IV lung adenocarcinoma underwent surgical resection of brain metastasis followed by several lines of chemotherapy. Nivolumab was initiated as the third line chemotherapy. Case 2. A 66-year-old man relapsed after undergoing surgical resection of cT1bN0M0 stage IB squamous cell carcinoma of the lung. Several lines of chemotherapy were administered; nivolumab was initiated as the fourth line. In both cases, a blood test after the initiation of nivolumab revealed increased levels of free triiodothyronine (FT3), free thyroxine (FT4), and anti-thyroglobulin antibody (TgAb), and decreased levels of thyroid-stimulating hormone (TSH). The clinical findings were consistent with those of silent thyroiditis. Nivolumab therapy was continued and the regression of the tumors was remarkable. Conclusion. Silent thyroiditis is one of clinical features of thyroid dysfunction when only TgAb emerges among the thyroid auto-antibodies induced during nivolumab therapy. Thus, it is recommended that thyroid function test be performed at regular intervals in order to detect the induction of thyroid dysfunction by nivolumab therapy at an early stage.
