Patients with carcinoma of unknown primary with isolated carcinomatosis on presentation: Clinicopathologic features and survival data.

4123 Background: Isolated or predominant carcinomatosis is not an uncommon presentation in patients with carcinoma of unknown primary (CUP). Primary peritoneal serous carcinoma (PPSC) is a well studied favorable CUP subset though data on non–PPSC is lacking and this group comprises of a large differential (gastric, colorectal, appendiceal, pancreatico-biliary and other cancer profiles). Information on the clinicopathologic characteristics and survival of these patients can help articulate a management strategy for these patients. Methods: Review of a M. D. Anderson Cancer Center CUP database from 2005 to 2010 has identified 64 patients in an ongoing study. Patients with predominant disease sites other than peritoneum/omentum were excluded. Data on demographics, imaging, detailed pathology, treatment, clinical course and survival was collected. Results: Median age of the patients is 56 years (range 31-86) and 38% are male. 13 (20%) women presented with typical PPSC. Immunohistochemistry (IHC) for all patie...