Stage IIIA KRAS p.G12V lung adenocarcinoma: pathologic complete response after chemoimmunotherapy and surgery

What happened, in summary

A 77-year-old woman with a 17 pack-year smoking history had a small 2 cm ground-glass opacity in the right lower lung that was first noticed during evaluation for interstitial lung disease. She was referred for biopsy but was lost to follow-up. Four years later, after recovering from COVID-19, worsening dry cough and intermittent coughing of blood brought her to the emergency department. CT now showed an 8 cm right lower-lobe mass. Biopsy confirmed invasive lung adenocarcinoma with a KRAS p.G12V mutation. PD-L1 staining was 0% in tumor cells and below 1% in tumor-associated inflammatory cells. Nodal staging by endobronchial ultrasound at stations 4L, 7, and 11R was negative, and PET/CT plus brain MRI showed no distant metastasis. She was clinically staged T4N0M0 / Stage IIIA. Her tumor board recommended induction chemoimmunotherapy followed by surgery. She completed 3 cycles of cisplatin, pemetrexed, and nivolumab, with stable disease on PET/CT. Before surgery, she entered a prehabilitation program with physical therapy and nutritional support. She then underwent robotic-assisted thoracoscopic right lower-lobe lobectomy with mediastinal lymph-node dissection. Dense adhesions were found between the tumor and chest wall, but biopsy of that area showed no malignancy. Because the mass adhered to the right upper lobe, an en bloc wedge resection was performed to ensure margins. She was discharged on postoperative day 2. Final pathology showed a pathologic complete response, and 12-month surveillance imaging showed no recurrence. Her postoperative course was smooth: the chest tube was removed, she received multimodal pain control, and her 2- and 6-week follow-up visits progressed as expected.