Clinicopathologic feature of microsatellite stable early-onset colorectal cancer

Abstract

Introduction: Recent epidemiological studies suggest a significant increase in young adults diagnosed with colorectal cancer (CRC) despite a recent decrease in the overall incidence andmortality. Early-onset colorectal cancers (EOCRCs) can be suggestive of hereditary predisposition, but hereditary syndromes account for only approximately 20%of EOCRCs.Most studies onEOCRCs both include hereditary and sporadic forms which result in discrepancies in clinical characteristics and oncologic outcomes. Wedescribe the oncologic outcomes and clinicopathologic features of microsatellite-stable EOCRCs. Method(s): Among 5,191 patients with CRC who underwent surgical resection between 2005 and 2013, 4,398 patients presented microsatellite-stable (MSS) colorectal cancer. Patients were categorized into EOCRC and late-onset CRC (LOCRC) according to a cut-off age of 42 which was determined using the Cox proportion hazard coefficient. Result(s): There were 183 EOCRC (4.2 %) and 4,215 LOCRC (95.8 %) with MSS features. The mean age of EOCRC and LOCRC was 37.1+/-4.7 and 63.7+/-9.9 years, respectively. The median follow-up period was 74 months (range: 1-160 months). Rectal location (41.6% vs. 34.6%, p=0.034), lymph node metastasis (53.9% vs. 46.8%, p=0.003), lymphatic invasion (37.7% vs. 31.2%, p=0.042) and distant metastasis at diagnosis (21.7%vs. 15.7%, P=0.008) were frequent in EOCRC than LOCRC, respectively. Gender, histologic type, venous invasion, and perineural invasion were not significantly different between two groups. While the overall survival (OS) rate was insignificant between EOCRC and LOCRC (5-year OS 62.0% vs. 67.0%, p=0.579), 5-year disease-free survival (DFS) of EOCRC was worse than LOCRC (73.3% vs. 80.9%, p=0.012). The difference between EOCRC and LOCRC in DFS was prominent in left colon cancers with stage II and III (5-year DFS 67.2% vs. 82.7%, p=0.002) Conclusion(s): MSS EOCRC is diagnosed in an advanced stage and the DFS of MSS EOCRC is worse than LOCRC, especially in left colon cancer.