541P - The Histological Importance of Signet Ring Cell and Mucinous Adenocarcinoma on Outcomes in Patients with Colorectal Cancer

Abstract

ABSTRACT The diagnosis of signet ring cell carcinoma (SRC) and mucinous adenocarcinoma (MC) represents approximately 1% and 15% of all colorectal cancers (CRC) respectively. Both entities have an aggressive biological behavior, but SRC tends to be the worst. A retrospective revision of cases was done in our institution to evaluate the clinical relevance, including metastasic patterns and overall outcome of patients with a SRC and MC component in patients with colorectal cancer. Methods Clinical charts of all patients with a diagnosis of primary CRC were reviewed between 2001 and 2011 at our institution; those with a histological component of SRC and MC adenocarcinomas were registered. The analysis of primary tumor site, stage at presentation, tumor grade, metastasic sites, symptoms and survival for each group were performed and compared. Results A total of 530 patients with primary CRC were identified. Signet cell was accounted for in 4% of patients with colorectal cancer, 14% had MC and the rest pure adenocarcinoma (72%). Median age of diagnosis for non-signet/non-mucinous adenocarcinomas was 61 years in comparison to 47 years for mucinous and signet cell carcinoma. SRC presented at more advanced stages III/IV at diagnosis (72%) more often than mucinous (46%) and highest tumor grade (SRC, 47%; MC 28%). There was no significant difference in location of primary cancer in both histologic types, presenting principally in ascending colon (28% vs 38%) and the rectum (28% vs 26%). Patients with a component of SRC and MC metastasized in a large proportion to the peritoneum and ovaries (80%) followed by ovary and lung. The most frequent symptom was abdominal pain (57%) in both groups. SCR carcinoma had significantly worse overall five-year relative survival than MC (25% vs 60%; p Conclusion SRC in colorectal cancer has a very poor prognosis in comparison to other histologic types. The clinical and pathologic course is outright aggressive and presents in a younger population of patients with a higher tumor grade and in more advanced stages than MC. Both groups share patterns of metastasis predominantly to peritoneum and ovaries. Disclosure All authors have declared no conflicts of interest.