A SEER Registry‐Based Analysis of the Management Strategies and Survival Outcomes of Colorectal Cancer With Isolated Synchronous Lung Metastases

ABSTRACT Background Current treatment guidelines for stage IV colorectal cancer (CRC) with isolated synchronous lung metastases are limited. This study aimed to assess the association between management strategies and cancer‐specific survival (CSS). Methods This study was a retrospective cohort analysis of patients with stage IV colorectal adenocarcinoma and isolated synchronous lung metastases from the SEER registry (2010–2022). Patients were grouped by treatment strategy: surgery‐only, chemotherapy‐only, or combined surgery and chemotherapy. The main outcome measure was 3‐year CSS, assessed by Kaplan‐Meier statistics and multivariable Cox regression to adjust for survival confounders. Results 5666 (6.9%) of 82,502 patients with stage IV CRC had isolated lung metastases. 736 (13%) were treated with surgery‐only, 1870 (33%) chemotherapy‐only, and 1908 (33.6%) surgery and chemotherapy; no treatment was recorded in 20.3% of patients. Chemotherapy alone was increasingly used over time (from 33.8% to 51.1%), whereas combined treatment decreased. Combined surgery and chemotherapys was associated with the highest 3‐year CSS (55.1%) compared with chemotherapy‐only (26.1%) and surgery‐only (21.7%) ( p < 0.001). Resection of both primary CRC and lung metastases combined with chemotherapy conferred the best 3‐year CSS (66.2%). Combined surgery for primary and metastatic tumors and chemotherapy was associated with significant mortality risk reduction (HR 0.31, p < 0.001) compared with chemotherapy‐only. Older age, signet‐ring cell histology, poor differentiation, N2 primary disease, elevated CEA, and perineural invasion were associated with reduced CSS. Conclusions Combined resection of primary CRC and synchronous lung metastases with chemotherapy was associated with the best survival outcomes. However, use of this combined strategy is employed in select patients and has decreased over time.