Purpose: There is little information comparing signet-ring cell carcinoma to common non-signet-ring cell colon and rectal cancers. The aim of this study was to better define the clinicopathologic differences between these two distinct entities.
Methods: Using a prospective database of 5,350 surgical patients with rectal cancers operated on at Memorial Sloan-Kettering Cancer Center between 1986 and 1997, 46 patients with signet-ring cell carcinoma were identified. Signet-ring cell carcinoma lesions were those in which signet-ring cells constituted more then 50 percent of the tumor. Six patients who presented with recurrent disease were excluded from the study. Control patients were matched for age, gender, TNM stage, primary site, procedure, and adjuvant therapy. Age, primary site of the tumor, stage at presentation, and survival times of patients with signet-ring cell carcinoma were also compared with 3,371 patients with primary non-signet-ring cell rectal cancers. Survival was calculated using Kaplan-Meier survival estimates.
Results: Mean age of the signet-ring cell carcinoma group was 59 +/- 12 years and median age was 61 (range, 20-91) years. Male-to-female ratio was 1.1:1. Lymphatic and peritoneal spread was more common among the signet-ring cell carcinoma group. Approximately one-third of signet-ring cell carcinoma patients presented with metastatic disease. Mean survival time of the signet-ring cell carcinoma group was 45.4 months (95 percent confidence interval, 26.9-63.8) compared with 78.5 months (95 percent confidence interval, 62.0-94.9) for the control patients group; P = 0.02 by the log-rank test. The cumulative survival curve of patients with signet-ring cell carcinoma resembles that of patients with poorly differentiated rectal cancers.
Conclusions: Patients with signet-ring cell carcinoma of the colon and rectum have a worse prognosis compared with matched controls with the same stage of disease.