Immunotherapy and Thyroid Dysfunction: Relevance to Nuclear Medicine

Area of Science:

• Oncology
• Endocrinology
• Immunology

Background:

• Small cell lung cancer (SCLC) is a highly aggressive form of lung cancer.
• Immunotherapy, particularly immune checkpoint inhibitors like nivolumab, is increasingly used in SCLC treatment.
• Immune-related adverse events (irAEs) are common with immunotherapy, affecting various organs.

Observation:

• A 66-year-old woman with stage IIB SCLC received nivolumab immunotherapy.
• She developed thyrotoxic symptoms (low TSH, high free thyroid hormones) after 2 months.
• Thyroid uptake and scan showed diffusely decreased uptake, indicating reduced function.

Findings:

• The patient's condition progressed to hypothyroidism within weeks.
• Thyroid-stimulating hormone (TSH) levels were suppressed, while free thyroid hormone levels were elevated initially.
• Radioiodine uptake was significantly decreased (0.7% at 4 hours, 0.3% at 24 hours).

Implications:

• These findings suggest nivolumab-induced thyroiditis as the cause of the patient's thyroid dysfunction.
• This case highlights the importance of monitoring thyroid function during nivolumab therapy for SCLC.
• Early recognition and management of irAEs like thyroiditis are crucial for patient outcomes.