Treatment outcomes and prognostic factors in patients with colorectal cancer and synchronous lung metastases in the conversion therapy era.

Purpose: The Japanese Grade Classification based on the status of pulmonary and mesenteric nodal metastases and the presence of extrapulmonary metastases had a prognostic value in patients with colorectal lung metastases previously. Because the survival of such patients has improved in the era of conversion therapy, this classification needs to be reaudited.

Methods: This study reviewed the treatment sequences of 126 colorectal cancer patients with synchronous lung metastases between 2010 and 2022 at our hospital. Patients were divided into Japanese Classification Grade A, B, and C. Prognostic factors for overall survival (OS) were analyzed.

Results: Thirty patients were initially diagnosed with resectable disease. Among these, 6 (35%) of 17 patients who were scheduled to undergo upfront surgery developed unresectable disease. In contrast, 3 (23%) of 13 patients receiving neoadjuvant therapy could not undergo curative resection. Twelve (13%) of 96 patients with initially unresectable metastases underwent conversion to complete resection after systemic therapy. On multivariate analysis, curative resection and H3 (> 5 liver metastases and maximum diameter > 5 cm) at diagnosis were independent prognostic factors, whereas the Japanese Grade Classification was not associated with OS.

Conclusion: Instead of the Japanese classification, a new prognostic classification incorporating H3 should be established.