Incidence, treatment, and survival of isolated patients with colorectal cancer lung metastases: A registry-based retrospective cohort study.

Background: The benefit of surgical resection for colorectal cancer (CRC) lung metastases is unclear. The aim was to investigate the incidence, treatment strategy, and 5-year overall survival (OS) in CRC patients with isolated lung metastases.

Methods: This registry-based retrospective cohort study included patients treated with curative resection of CRC within the county of Skåne during the period 2010-2016, who had synchrone or metachrone isolated lung metastases. Exclusion criteria were previous or concurrent metastases at other organ sites. Patients were identified in the Swedish Colorectal Cancer Registry (SCRCR) and data were retrieved from SCRCR and medical charts. Patients were divided into groups based on whether they had synchronous or metachronous lung metastases and curative or palliative treatment intent. The primary endpoint was 5-year OS. Multivariable Cox-regression and Kaplan-Meier survival analysis were performed.

Results: Of 8457 curatively resected CRC patients, 93 (1.1%) had isolated lung metastases (53 synchronous/40 metachronous). Of these, 53 were treated with curative intent, 51 (96%) of whom were managed surgically. The remaining 40 patients were treated palliatively and either with chemotherapy or with best supportive care. Five-year OS was 42% (39/93), median 50 months (IQR: 24-60) for the entire cohort, and 68% (36/53), median 60 months (IQR 55-60) and 7.5% (3/40), median 22 months (IQR: 12-33) for curative and palliative patients, respectively. In multivariable analysis, age (hazard ratio (HR): 1.04, confidence interval (CI): 1.01-1.07), multiple lung metastases (HR: 1.64, CI: 1.08-2.47), and unilateral distribution (HR: 0.41, CI: 0.20-0.84) were predictors of OS.

Conclusions: Isolated CRC lung metastases are rare. Curative treatment was associated with considerably better 5-year OS than palliative treatment (68% vs 8%). Age, solitary metastases, and unilateral distribution were predictors of survival.