What happened, in summary

A 75-year-old man was diagnosed with Stage III squamous cell carcinoma in the right lower lobe of his lung. He received concurrent cisplatin and docetaxel chemotherapy with chest radiation. The lung cancer had a partial response after chemoradiotherapy. He then began durvalumab consolidation every 2 weeks, and the response was maintained through at least 9 cycles. During the 14th cycle, he developed swelling near the left submandibular gland. CT showed enlarged cervical lymph nodes while the primary lung tumor remained substantially smaller than before treatment. Biopsy of a submandibular lymph node and blood testing led to a separate diagnosis of adult T-cell leukemia/lymphoma associated with HTLV-1. Because this new hematologic cancer was considered the more urgent problem, durvalumab and the lung-cancer treatment pathway were stopped. He then began CHOP chemotherapy for the leukemia/lymphoma, with mogamulizumab added from the second cycle. Those drugs were treatment for the separate blood cancer rather than the lung cancer. The lymphadenopathy improved after the new treatment. During the interval between stopping durvalumab and starting therapy for adult T-cell leukemia/lymphoma, the lung cancer showed no progression. The Stage III lung cancer remained controlled despite the major treatment change caused by the second malignancy.