Do metastatic colorectal cancer (mCRC) patients with late relapse after curative surgery have a better survival?

Methods: A retrospective cohort study was perfomed to compare the characteristics and survival of relapsed patients with metachronous (m) mCRC. Patients were categorised into relapse at < 2yrs, 2-5 yrs and > 5yrs following their initial surgery. Univariate log-rank tests and and multivariate Cox regression was performed to determine whether time to relapse (TTR) and other factors were associated with overall survival (OS). Results: Of 750 mmCRC, 56% percent relapsed at < 2yrs, 32.4% at 2-5yrs, and 11.6% at > 5yrs. Patient characteristics are summarised in the table. Median OS, from the time of diagnosis of the recurrence, was 17 mths, 24.8 mths, and 26.5 mths respectively. Age (HR = 1.01, 95% CI=1.005-1.02, p=0.003) and liver resection (HR = 0.2, 95% CI=0.1-0.3, p < 0.001) were significant independent predictors of OS. TTR was also significantly associated with OS (HR = 0.75, 95 % CI = 0.60-0.93 and HR = 0.73, 95% CI = 0.53-1.01 respectively for 2-5 yrs and > 5 yrs versus < 2yrs, p < 0.05). There was no significant difference in survival between patients that relapsed at 5 yrs or later compared to those who relapsed between 2 and 5 yrs (HR = 0.98, 95% CI = 0.69-1.38, p = 0.90). Conclusions: TTR predicted shorter survival for mmCRC patients whose relapse occurred within 2 yrs. However, when comparing TTR 2-5 yrs and TTR > 5 yrs, there is no evidence that mmCRC patients with later relapse have a better prognosis.