Pulmonary Metastasectomy in Colorectal Cancer (PulMiCC) cohort study: analysis of case selection, risk factors and survival in a prospective observational study of 512 patients

Aim We wanted to examine survival in patients with resected colorectal cancer (CRC) whose lung metastases are and whose are not resected. Methods Teams participating in the study of Pulmonary Metastasectomy in Colorectal Cancer (PulMiCC) identified potential candidates for lung metastasectomy and invited their consent to join Stage 1. Baseline data related to CRC and fitness for surgery were collected. Eligible patients were invited to consent for randomisation in the PulMiCC RCT(Stage 2). Sites were provided with case report forms for non-randomised patients to record adverse events and death at any time. They were all reviewed at one year. Baseline and survival data were analysed for the full cohort. Results Twenty-five clinical sites recruited 512 patients from October 2010 to January 2017. Data collection closed in October 2020. Before analysis 28 patients with non-CRC lung lesions were excluded and 3 had withdrawn consent leaving 481. The date of death was known for 292 patients, 136 were alive in 2020, and 53 at earlier time points. Baseline factors and five-year survival were analysed in three strata: 128 non-randomised patients did not have metastasectomy; 263 had elective metastasectomy; 90 were from the randomised trial. The proportions of solitary metastases for electively operated and non-operated patients were 69% and 35%. Their respective five-year survivals were 47% and 22%. Conclusion Survival without metastasectomy was greater than widely presumed. Difference in survival appeared to be largely related to selection. No inference can be drawn about the effect of metastasectomy on survival in this observational study.