What happened, in summary

A 74-year-old woman with a remote history of breast cancer was evaluated after a chest X-ray for chest pain revealed a new density in the right lower lobe. She had a 40 pack-year smoking history and chronic obstructive lung disease. CT showed a 3.3 × 3.1 × 2.8 cm mass in the right lower lobe, and CT-guided biopsy confirmed primary squamous cell carcinoma of lung origin with no EGFR mutation detected. PET/CT showed uptake limited to the lung mass, without hilar, mediastinal, or distant disease, giving a clinical stage of Stage IB (cT2aN0M0) non-small cell lung cancer. Because pulmonary function testing showed limited lung reserve and she was considered a poor surgical candidate, she received definitive stereotactic body radiation therapy. Treatment was planned with 4D CT motion assessment and delivered as 50 Gy in 4 daily fractions using VMAT and daily cone-beam CT guidance. Surveillance CT scans followed at 3, 6, 10, and 13 months. At 20 months after SBRT, a new 6-mm nodule appeared in the opposite, left lower lobe. Biopsy confirmed a metachronous second primary squamous cell lung cancer, and it was treated with a similar SBRT course. That second cancer remained without progression or side effects 5.1 years later. The original right-lower-lobe site became concerning again: PET/CT at about 3.8 years showed increased uptake, and biopsy at 4.3 years confirmed persistent squamous cell carcinoma confined to the original treatment site. Repeat SBRT was not recommended because of normal-tissue injury risk; percutaneous thermal ablation or HDR brachyablation was recommended.