Metastatic colorectal carcinoma with signet-ring cells: Clinical, histological and molecular description from an Association des Gastro-Entérologues Oncologues (AGEO) French multicenter retrospective cohort.

Abstract

Metastatic signet-ring cell colorectal carcinoma is rare. We analyzed its clinicopathological and molecular features, prognostic factors and chemosensitivity. Retrospective study from 2003 to 2017 in 31 French centers, divided into three groups: curative care (G1), chemotherapy alone (G2), and best supportive care (G3). Tumors were most frequently in the proximal colon (46%), T4 (71%), and poorly differentiated (86%). The predominant metastatic site was peritoneum (69%). Microsatellite instability and BRAF mutation were found in 19% and 9% (mainly right-sided) of patients and RAS mutations in 23%. Median overall survival (mOS) of the patients (n=204) was 10.1 months (95%CI: 7.9;12.8), 45.1 for G1 (n=38), 10.9 for G2 (n=112), and 1.8 months for G3 (n=54). No difference in mOS was found when comparing tumor locations, percentage of signet-ring cell contingent and microsatellite status. In G1, relapse-free survival was 14 months (95%CI: 6.5-20.9). In G2, median progression-free survival (PFS) was 4.7 months (95%CI: 3.6;5.9]) with first-line treatment. Median PFS was higher with biological agents than without (5.0vs 3.9 months, p=0.016). mSRCC has a poor prognosis with specific location and molecular alterations resulting in low chemosensitivity. Routine microsatellite analysis should be performed because of frequent MSI-high tumors in this population.