312 Patients With Very Early Onset Colorectal Cancer Have Increased Microsatellite Instability

Abstract

INTRODUCTION: The incidence of colorectal cancer (CRC) in young patients has been increasing. This has led to increase interest in the molecular patterns and epigenetics of CRC in this age group. Microsatellite instability has been noted to be a positive prognostic factor in CRC. We aimed to evaluate the disease and molecular characteristics of patients with early-onset CRC (40-49 years of age) and compare them with those of very early-onset CRC (<40 years of age). METHODS: A retrospective cross-sectional study was performed using our electronic pathology database. All patients diagnosed with CRC between January 2012 and September 2018 were included. Data regarding patient demographics, comorbid conditions and patient presentation was noted. We also noted information regarding the location, staging and molecular features of CRC. RESULTS: A total of 627 patients with CRC were identified. Out of these, 117 (18.6%) were younger than 50 years of age (early-onset CRC). From patients < 50 years of age, 74 (63.2%) had early-onset CRC (40-49 years of age) and 36.8% of patients had very early-onset (<40 years of age). The mean age was 45.4 in those between 40-49 years of age and 33.5 in those < 40 years of age. The most common complaint in early-onset CRC was rectal bleeding (44.6%), while abdominal pain was the most common (39.5%) complaint in the very-early onset CRC group. There were no differences in stage of CRC among both groups. Microsatellite instability (MSI) was more common in patients with very early-onset CRC (40.7 vs 13.6%, P-value = 0.009) as compared to those with early onset CRC. Other clinical and molecular features of patients with very-early onset CRC are summarized in Table 1. CONCLUSION: There are unique clinical characteristics and molecular features in patients with very-early onset CRC. Our study shows that patients very early-onset CRC have increased MSI. Although our study limitations include a small sample size and an experience from a single center, our findings suggest that further understanding of molecular features in patients with very early-onset CRC is needed to improve diagnosis and management of CRC in this age group.