LAUSR

BACKGROUND High-risk features in Stage II colon cancer worsen survival and serve as an impetus for adjuvant chemotherapy. Limited data exists on the effect of multiple high-risk features on survival. OBJECTIVE To compare the survival of zero, one or multiple high-risk features in Stage II colon cancer, to Stage III disease. DESIGN Patients with Stage II and III colon cancer diagnosed between 2010 and 2016 were identified using the Survival, Epidemiology, and End Results database. Stage II patients were then classified by the presence of zero, 1, or 2+ of the following high-risk features: pathologic T4, perineural invasion, fewer than 12 lymph nodes assessed (< 12 lymph nodes), or poor histologic differentiation. Observed and cause-specific survival were calculated. Each group was then stratified based on whether chemotherapy was given. SETTINGS This study used the Survival, Epidemiology, and End Results database, 2010-2016. PATIENTS The patients had Stage II or III colon cancer. MAIN OUTCOME MEASURES The primary measure was 5-year observed survival and cause-specific survival. RESULTS A total of 65,831 patients were studied. 18,056 patients were Stage II with zero high-risk features, 9,426 with 1 high-risk features, and 3,503 with 2+ high-risk features. There were 34,842 patients were diagnosed with Stage III disease. The 5-year observed survival and cause-specific survival for patients with Stage II cancer with 2+ high-risk features (49.2%, 59.5%) were lower, compared to those without high-risk features (74.9%, 90.7%), with 1 high-risk feature (67.1%, 82.4%) or Stage III disease (59.1%, 68.1%) (p < 0.05). While chemotherapy is associated with improved cause-specific survival in Stage III disease, it is associated with worse cause-specific survival in patients with Stage II disease. LIMITATIONS This is a retrospective database analysis. Lymphovascular invasion, margin status, and clinical obstruction or perforation were absent from the dataset. CONCLUSIONS Multiple high-risk features in Stage II colon cancer predict worse survival than lymph node metastasis. Chemotherapy is associated with adverse cause-specific survival in patients with Stage II disease. Further study into this group should focus on the type and duration of adjuvant therapy, and biological features of these tumors. See Video Abstract at http://links.lww.com/DCR/B929.