What happened, in summary

A 51-year-old man with a long smoking history was diagnosed with Stage IV squamous cell cancer of the right lung. Enlarged mediastinal and hilar lymph nodes were present at diagnosis. He began first-line treatment with nab-paclitaxel and carboplatin together with tislelizumab and completed 4 cycles. Imaging showed improvement in the enlarged lymph nodes. During evaluation before another immunotherapy cycle, blood testing showed very low morning cortisol and ACTH levels. He had few obvious symptoms, and pituitary imaging was normal, but the clinical team diagnosed secondary adrenal insufficiency related to immunotherapy. Tislelizumab was paused while chemotherapy continued, and he started steroid hormone replacement. Thyroid replacement was also used temporarily until his thyroid tests normalized. More than 8 months later, his cortisol remained below normal, so immunotherapy had not been restarted. Updated follow-up found no recurrence or additional metastasis. His cancer had responded to treatment, but the endocrine side effect required prolonged monitoring and changed the treatment plan.