Stage IVA EGFR-mutated lung adenocarcinoma: stable disease on first-line osimertinib

What happened, in summary

This 79-year-old lifetime nonsmoker had major cardiopulmonary comorbidities, including chronic obstructive pulmonary disease, congestive heart failure, atrial fibrillation, and post-COVID pulmonary fibrosis. In September 2024, she developed worsening shortness of breath, pleuritic chest pain, and a large left pleural effusion. CT showed an encapsulated left pleural effusion with pleural thickening, pleural-pericardial adhesions, fibrosis, and bronchiectasis, without obvious mediastinal lymphadenopathy or discrete pulmonary nodules. On 26 September 2024, she underwent video-assisted thoracoscopic surgery with pleural biopsy, pleurodesis, and drainage of 1000 mL of serous fluid. Pathology from the parietal pleura showed metastatic lung adenocarcinoma. Immunohistochemistry was TTF-1-positive, ALK-negative, and PD-L1 TPS 30%. Molecular testing found an EGFR exon 19 deletion plus a baseline EGFR exon 20 T790M mutation before systemic therapy began. Total-body CT on 31 October 2024 staged the disease as cT4N0M1a, Stage IVA, because of malignant pleural effusion and malignant pleural-pericardial adhesions. Because of her EGFR profile, age, comorbidities, and advanced stage, she started osimertinib 80 mg once daily on 28 November 2024, with denosumab given on a scheduled basis. Follow-up was structured with monthly laboratory checks and contrast-enhanced CT every 3-6 months. CT imaging through January 2026 showed no progressive disease, no recurrent pleural effusion, and no new visceral, nodal, brain, or bone lesions. The target pulmonary and pleural disease remained stable by RECIST 1.1. A right frontal extra-axial lesion was stable and interpreted radiologically as meningioma rather than metastasis. Clinically, her ECOG performance status improved from 2 to 0, quality of life improved, and treatment continued without adverse events, dose reductions, interruptions, or discontinuations.