A. Ejaz2, L. Casadaban1, M. Kobialka1, A. V. Maker1 1University Of Illinois At Chicago,Chicago, IL, USA 2Johns Hopkins University School Of Medicine,Baltimore, MD, USA
Introduction: The impact of negative prognostic factors among patients with stage II colon cancer is ill-defined. We sought to define the incidence and impact of microsatellite instability (MSI), lymphovascular invasion (LVI), and perineural invasion (PNI), features often not captured in large cancer population databases, on overall (OS), and recurrence-free survival (RFS) following resection among patients with stage II colon cancer.
Methods: Using a prospectively-collected multi-institutional database across 8 hospitals, we identified 345 stage II colon cancer patients who underwent curative resection between 2010-2013. The impact of high-risk microscopic features (MSI, LVI, PNI) and clinicopathologic and treatment factors were evaluated using multivariate regression models.
Results: In a subset of 175 patients for whom high-risk microscopic features were available, median patient age was 72 (IQR: 64, 81) years. The majority of patients were white (77.7%) and female (52.6%). On pathology, most patients had a T3 tumor (81.3%) with a mean of 20.9±10 lymph nodes examined. High-risk microscopic features were common as 76.0% of patients had evidence of MSI-stable (63.2%), LVI (31.9%), or PNI (7.1%). Adjuvant chemotherapy was administered in 30 (17.1%) patients. After a median follow-up of 37 months, 31 patients (17.7%) died within the study period and median overall survival (OS) was not reached. After adjusting for patient-, treatment-, and tumor-related factors, MSI-stable (HR: 1.20; P=0.72), LVI (HR: 0.89; P=0.85), and PNI (HR: 1.98; P=0.48) were not associated with a worse OS. Similarly, recurrence-free survival was also not affected by high-risk microscopic features (all P>0.05).
Conclusion: Over three-fourths of patients with resected stage II colon cancer possess at least one high-risk microscopic feature. The presence of these high-risk features did not impact short-term OS or RFS. Further studies on OS and RFS among patients with stage II colon cancer and high-risk microscopic features are warranted.