Outcomes of Thoracic Surgical Oncology Group 103: Multimodality management in risk-stratified patients with lung-limited metastatic colorectal cancer

Objective Thoracic Surgery Oncology Group 103 was a prospective multi-institutional trial that aimed to (1) evaluate the role of perioperative chemotherapy for low-risk patients with metastatic colorectal cancer undergoing pulmonary metastasectomy and (2) characterize the impact of surgery on outcomes for high-risk patients with metastatic colorectal cancer receiving chemotherapy. Methods From July 2018 to September 2023, patients with histologically confirmed primary colorectal cancer and lung metastases amenable to complete margin-negative resection from 3 institutions were enrolled and stratified by low- and high-risk clinical features and randomized accordingly within 2 treatment paradigms. Results A total of 22 and 26 patients were enrolled in the low- and high-risk cohorts, respectively. Randomization within the low-risk cohort resulted in 8 individuals (40.0%) receiving perioperative chemotherapy and surgery (+Chemo) and 12 patients (60.0%) undergoing surgery alone (–Chemo). Median overall survival was unable to be calculated for either group, and median recurrence-free survival was 21.8 months for +Chemo and not yet reached for –Chemo ( P = .33). Among high-risk patients receiving chemotherapy, 8 (36.4%) remained on chemotherapy only (–SX) and 14 (63.6%) underwent pulmonary metastasectomy (+SX). Partial response to initial chemotherapy was achieved in 4 (50.0%) –SX patients and 6 (42.9%, P = 1.00) +SX patients. No deaths occurred in either group, and median recurrence-free survival was 33.4 months in the –SX group and 55.8 ( P = .95) months in the +SX group. Conclusions Patient accrual targets were not reached, leaving this study underpowered; as such, all analyses are descriptive and hypothesis generating. We were unable to determine differences in survival in the high-risk cohort; however, our findings suggest that adequately selected low-risk individuals can be treated with up-front pulmonary metastasectomy without additional lung-directed chemotherapy.