Cohort study of long-term survival and recurrence patterns following operative management of colorectal liver metastasis — is follow-up beyond 5 years warranted?

Aims To evaluate the patterns of overall survival (OS) and recurrence following surgical resection of colorectal liver metastases (CRLM). Methods In compliance with STROCSS guideline, a single-centre retrospective cohort study was conducted. All consecutive patients undergoing resection of CRLM between 2003 and 2019 were considered eligible for inclusion. The outcome measures included OS, recurrence-free survival (RFS), recurrence rate, time to recurrence (TTR) and longest TTR. Statistical analyses included simple descriptive statistics and Kaplan–Meier survival statistics. Results We included 486 liver resections in 472 patients. The estimated median OS and RFS were 5.1 years and 3.1 years, respectively. The probability of 1-year, 3-year, 5-year and 10-year OS was 93%, 69%, 50% and 34%, respectively. The probability of 1-year, 3-year, 5-year and 10-year RFS was 81%, 50%, 34% and 33%, respectively. Recurrence occurred in 56% (271/486) of patients, and the median TTR was 1.6 years (IQR: 0.8–2.7) with longest TTR of 4.8 years. Although there were no recurrences in the 66 patients that entered the 6th year, the 95% CI for true rate of recurrence in the population given these data is 0–5.4%. Conclusions Our results suggest that recurrences that occur after operative management of CRLM are almost certain to occur within the first 5 years even for patients surviving longer than 5 years. This does not disprove the requirement for follow up beyond 5 years. However, based on this data, we have altered our follow up from 10 to 6 years. The need for the 6th year of follow up will be reassessed in light of further observations.