Clinicopathology and Outcomes for Mucinous and Signet Ring Colorectal Adenocarcinoma: Analysis from the National Cancer Data Base

We evaluated clinical features and survival outcomes among patients with signet ring and mucinous histologies of colorectal adenocarcinoma by using data from the National Cancer Data Base (NCDB). Patients aged 18-90 years with colorectal adenocarcinoma diagnosed between 1998 and 2002 were identified from the NCDB. Site-stratified (colon vs. rectum) survival analysis was performed by multivariate relative survival adjusted for multiple clinicopathologic and treatment variables. The study included 244,794 patients: 25,546 (10%) with mucinous, 2,260 (1%) with signet ring, and 216,988 (89%) with nonmucinous, non-signet ring adenocarcinoma. Mucinous and signet ring cancers were more frequently right-sided (60% and 62%, respectively) than were nonmucinous, non-signet ring adenocarcinomas (42%, P < 0.001). Signet ring histology was associated with a higher stage (P < 0.001), and 77.2% of signet ring tumors were high-grade lesions, compared with 20% of mucinous and 17% of non-signet ring, nonmucinous adenocarcinomas (P < 0.001). After adjustment for covariates, signet ring histology was independently associated with higher risk of death [hazard ratio (HR) 1.42, 95% confidence interval (CI) 1.33-1.51, and HR 1.57, CI 1.38-1.77, for tumors located in the colon and rectum, respectively]. Mucinous tumors of the rectum (HR 1.22, CI 1.16-1.29), but not the colon (HR 1.03, CI 1.00-1.06), were associated with increased risk of death. Signet ring cell adenocarcinomas of the colon and rectum and mucinous adenocarcinomas of the rectum are associated with poorer survival. These aggressive histologic variants of colorectal adenocarcinoma should be targeted for research initiatives to improve outcomes.