Secondary osteosarcoma developing 10 years after chemoradiotherapy for non-small-cell lung cancer

A 53-year-old female patient was admitted with pain and a progressively enlarging mass in the right upper chest. Chest computed tomography revealed a mass lesion in the region of the right upper ribs. Ten years prior to this admission, the patient had undergone right lobectomy for lung adenocarcinoma. One year after the surgery, follow-up computed tomography had revealed tumor recurrence in the mediastinal and supraclavicular lymph nodes, and the patient had been treated by chemoradiotherapy. Thereafter, regular follow-up had revealed no evidence of recurrence of the non-small-cell lung cancer. Histopathological findings revealed proliferation of spindle-shaped malignant tumor cells in a background of osteoid, consistent with the diagnosis of osteosarcoma. The location of the tumor was consistent with the radiation field. Based on the clinicopathological findings, the patient was diagnosed as having secondary osteosarcoma occurring as a result of the chemoradiotherapy administered previously for the recurrent non-small-cell lung cancer. Unfortunately, the patient died of rapid progression of the osteosarcoma within a week of admission to the hospital. The autopsy revealed contiguous invasion by the tumor of the heart, with massive thrombus formation. The peripheral pulmonary arteries were diffusely occluded by metastatic tumors. Our case serves to highlight the risk of development of secondary sarcoma as a life-threatening late complication after chemoradiotherapy for locally advanced non-small-cell lung cancer, even after complete cure of the primary tumor.