Long disease-free interval diminishes the prognostic value of primary tumor stage for patients with colorectal cancer liver metastases

Background: It is assumed that the impact of primary tumor stage (PTS) on prognosis gradually weakens with increasing disease-free interval (DFI) from colorectal cancer resection to liver metastases. Methods: Data from 733 patients undergoing hepatectomy in the Hepato-pancreato-biliary Surgery Department I of Peking University Cancer Hospital were retrospectively analyzed. Early and late metastases were defined as DFI <= and > 12 months, respectively. Results: In early metastases group, patients with T-4 stage had a significantly worse recurrence-free survival (RFS) and overall survival (OS) than those with T1-3 stage (P = 0.002 and P < 0.001, respectively). Patients with N1-2 stage disease also demonstrated a worse RFS and OS than those with N-0 stage (P = 0.006 and P = 0.007, respectively). In late metastases group, patients with T-4 and T1-3 stages as well as patients with N1-2 and N-0 stages, had comparable RFS (P = 0.395 and P = 0.996, respectively) and OS (P = 0.387 and P = 0.684, respectively). T and N stages were independent prognostic predictors only in patients with early metastases. Conclusion: The impact of PTS on prognosis is diminished with increasing DFI and limited only to patients with early metastases.