What happened, in summary

A 72-year-old woman with a heavy smoking history was diagnosed with primary lung cancer in the right upper lobe, staged cT1N0M0 Stage IA. Her respiratory function was not strong enough for surgical resection, so she was treated with stereotactic body radiation therapy instead. SBRT delivered 48 Gy in 4 fractions using 4-MV and 10-MV linear accelerator beams. Before treatment, her serum CEA was elevated at 14.7 ng/mL, while KL-6 and SP-D were normal; no tumor genomic biomarker testing was reported. Follow-up CT scans were performed at 2, 6, 9, and 12 months. At 2 months, irregular patchy consolidation appeared in the treated field and was interpreted as radiation pneumonitis. By 6 and 9 months, that area retracted in a pattern considered typical radiation fibrosis. At 12 to 13 months, however, mass-like consolidation enlarged around the treated area, raising concern for local recurrence. FDG-PET showed uptake with SUVmax 5.61, but CT-guided biopsy showed class II cytology and no cancer cells. Because there was no definite evidence of malignancy, and because of her age and poor lung function, doctors chose close follow-up rather than surgery. The consolidation later began to retract, and tumor and inflammation markers gradually decreased, apart from a transient rise during left lower-lung pneumonia. At 40 months after SBRT, she was alive without local recurrence. The confusing part of her follow-up was that radiation fibrosis can look like a growing mass on CT and can also show FDG uptake on PET. Her doctors balanced this concern against her limited lung reserve and chose biopsy plus close monitoring.