High-Grade Neuroendocrine Carcinomas (Hgnecs) Of The Colon And Rectum: A Single-Institution Retrospective Analysis.

e14040 Background: HGNECs of the colon and rectum are uncommon with no standard treatment guidelines. Methods: We undertook a single institution IRB approved retrospective evaluation of patients (pts) with HGNECs of the colon and rectum from 1991-2010. 95 pts with histologically confirmed HGNEC with adequate follow up information for survival analysis were identified. Results: Median age of pts was 55 (range 34 to 89) and the median follow up was 12.5 months. 53% were male. Majority of the HGNECs had poorly differentiated and/or small cell histology (92.6%) while the remaining had large cell histology. Immunohistochemistry demonstrated positivity with chromogranin, synaptophysin and neuron specific enolase in 59%. 92.6% and 86.7% cases, respectively. Rectosigmoid was the most common primary site (55%) followed by the cecum (17%). Metastatic disease was present at diagnosis in 63% pts. Liver was the most common site of metastasis (92%) and was an isolated site of metastatic disease in 51% of pts. Pts with right sided tumors presented more often with metastatic disease at initial diagnosis (79%) compared to patients with left sided tumors (38%) and rectosigmoid tumors (58%), (p=0.046). Among pts with localized disease, 80% underwent resection of primary tumor. Distribution among stages I, II and III were 13%, 8% and 79%, respectively based on histopathologic and operative staging. Among the 28 pts who underwent surgery 6 underwent neo-adjuvant therapy, 17 underwent adjuvant therapy and 5 received both. Among pts with metastatic disease at presentation, 90% underwent first line palliative chemotherapy and 49% received second line palliative chemotherapy. Pts with localized disease had a median survival of 20.4 months and 5-year survival of 28%, while pts with metastatic disease had a median survival of 8.6 months. Conclusions: This single-institution retrospective analysis suggests that HGNEC arising in the right colon may have a more aggressive biology compared to other sites in the colon and rectum, however even localized disease has a very low 5-year survival. Further evaluation of treatment patterns in this cohort may provide guidance on optimized treatment approaches in a poor prognosis group of pts.