Impact of histological subtype on the prognosis of patients undergoing surgery for colon cancer

Background: The effect of the histological subtype on the prognosis of patients undergoing surgery for colon cancer (CC) is not completely understood. Methods: The Surveillance, Epidemiology, and End Results (SEER) 2004–2014 database was used to compare the long-term outcomes of patients undergoing colon resection for classical adenocarcinoma (CA), mucinous adenocarcinoma (MUC), and signet-cell adenocarcinoma (SC). Results: A total of 153 317 (89%) patients had CA, 16 660 (10%) MUC while 1810 (1%) patients had SC subtype. Patients with MUC and SC more frequently had a poorly differentiated CC and were more likely to present with advanced disease compared with CA patients (P < 0.001). Patients with CA had a 5-year OS of 62% versus 55% and 34% for patients with MUC and SC subtypes, respectively (P = 0.001). On multivariable analysis, site of cancer, tumor grade, and TNM stage were associated with prognosis (all P < 0.001). After controlling for these risk factors, patients with MUC (HR, 1.09, P < 0.001) and SC (HR, 1.47, P < 0.001) had a roughly 10% and 50% increased hazard of death, respectively, compared with CA patients. Conclusions: MUC and SC are distinct subtypes of CC associated with a worse prognosis. These data can help inform discussion about prognosis and possibly direct adjuvant management.