Chemotherapy, immunotherapy, and surgery for lung cancer that spread to the foot

What happened, in summary

A 70-year-old woman sought care for pain in her right ankle and foot. MRI showed extensive abnormalities in the bones of the midfoot and hindfoot. Open biopsy found metastatic adenocarcinoma with staining that supported a lung primary. Chest CT then identified a 1.5 cm nodule in the left lower lobe. Bone scanning showed disease in the right foot and ankle but no other confirmed bone metastases. Her lung cancer was classified as T1bN0M1b. Radiation to the right foot produced marked improvement in her symptoms. She began pemetrexed and carboplatin, and pembrolizumab was added after testing showed PD-L1 expression of 20%. Next-generation sequencing found no actionable mutations. After four cycles, PET/CT showed a significant response. She then underwent robotic wedge resection of the left lower lobe with mediastinal lymph-node dissection. The removed nodule showed fibrosis, scar, chronic inflammation, and reactive change without residual carcinoma. A later scan raised concern about the right shoulder and upper arm, but MRI findings were indeterminate and could have represented marrow changes rather than metastasis. Continued systemic chemotherapy and additional radiation were being considered at the latest follow-up.