Stage 4 lung cancer: complete response to chemoimmunotherapy and surgery

What happened, in summary

A 58-year-old Asian man with hypertension was admitted on February 22, 2023, after 2 months of cough with bloody sputum. He had no smoking or alcohol history. PET/CT on March 31 showed a malignant-appearing left lower-lobe mass with obstructive inflammation and atelectasis, possible adjacent pleura and diaphragm involvement, left pulmonary hilar lymph-node metastasis, right adrenal metastasis, and left pleural effusion. Pathology from April 4 showed poorly differentiated squamous cell carcinoma. Immunohistochemistry was P40-positive, CK5/6-positive, TTF-1-negative, Napsin A-negative, CEA-negative, and Ki-67 60%. The clinical stage was cT4N1M1b, and next-generation sequencing found an EGFR exon 20 p.S768_D770 duplication. PD-L1 TPS was 70%. Treatment began April 10 with albumin-bound paclitaxel plus cisplatin. Subsequent cycles on April 29, May 24, and June 17 used albumin-bound paclitaxel, carboplatin, and pembrolizumab every 3 weeks. He developed grade IV myelosuppression requiring leukocyte-boosting therapy. After 4 cycles, the primary tumor shrank markedly and the right adrenal metastasis disappeared. On July 25, 2023, he underwent conversion surgery with left lower lobectomy, lymph-node dissection, left upper-lobe wedge resection, and partial diaphragm resection. Pathology showed no residual cancer in the lung, bronchial stump, diaphragmatic nodule, or examined lymph nodes, consistent with pathologic complete response and postoperative ypT0N0Mx. Pembrolizumab maintenance resumed September 7, 2023. As of May 7, 2024, CT follow-up showed no evidence of disease. Echocardiogram, blood tests, CT imaging, and thyroid-function testing showed no immune-related myocarditis, hepatitis, pneumonia, hypothyroidism, or hyperthyroidism while he continued pembrolizumab maintenance. The surgical procedure was extensive because the tumor had involved the left lower lung region with suspected adjacent structures and pleural adhesions, requiring conversion from video-assisted thoracoscopy to open thorax. That operative detail helps explain why conversion surgery was clinically notable after systemic response.