Scatter patterns in lymph node metastases as a novel prognostic indicator in patients with stage III/N2 colorectal cancer

To classify patients with stage III/N2 colorectal cancer into high- and low-risk groups for recurrence, the present study compared clinicopathological features by immunohistochemical staining. The single-center analysis included 53/668 patients (7.9%) with stage III/N2 colorectal cancer who underwent radical resection between January 2006 and December 2014. The present study examined cancer cell distribution in metastatic lymph nodes and classified patients into a group with circumferential localization patterns like a cystic mass (CLP) and a group with scatter patterns like fireworks (SPF). Subsequently, 5-year relapse-free survival (5Y-RFS) and 5-year overall survival (5Y-OS) rates were compared and the histological type (differentiation degree) of the primary adenocarcinoma was included. The CLP group included 16 patients (30.2%) and the SPF group included 37 patients (69.8%). The 5Y-RFS rates in these groups were 75.0 vs. 37.8%, respectively (P=0.021), and the 5Y-OS rates were 81.3 vs. 48.6% (P=0.033). Patient clinicopathological characteristics exhibited no significant differences between groups. The adenocarcinoma was well differentiated in 14 patients (Well; 26.4%) and moderately (Mod; n=37) or poorly (Por; n=2) differentiated in 39 patients (Mod+Por; 73.6%). Patients were further classified into four groups: Well/CLP (n=6), Well/SPF (n=8), Mod+Por/CLP (n=10) and Mod+Por/SPF (n=29). For Well/CLP vs. Well/SPF, the 5Y-RFS rates were 66.7 vs. 25.0%, respectively (P=0.293), and for Mod+Por/CLP vs. Mod+Por/SPF (80.0 vs. 41.4%; P=0.052), the respective values for 5Y-OS were 66.7 vs. 50.0% (P=0.552) and 90.0 vs. 48.3% (P=0.059). Based on the aforementioned results, the CLP group was considered a low-risk group for recurrence with a relatively good prognosis; however, the SPF group was considered a high-risk group for recurrence with a poor prognosis, suggesting a need for more potent multi-combination chemotherapy in these patients from the early postoperative period.