Is the presence of acellular mucin in rectal cancer patients with a pathologic complete response to preoperative chemoradiation of prognostic significance

4119 Background: Rectal cancer patients who achieve a pathologic complete response (pCR) to preoperative chemoradiation have decreased local recurrence and improved survival rates. The presence of acellular mucin pools in the resected specimen is frequently reported; however, the prognostic significance of this finding is unknown. The objective of this study was to determine the prevalence and prognostic significance of acellular mucin within resected specimens of rectal cancer patients with a pCR to preoperative chemoradiation. Methods: Data from a retrospective rectal cancer database was used to analyze clinical courses of 562 patients with nonmetastatic rectal adenocarcinoma treated with preoperative chemoradiation and mesorectal excision between 1989 and 2004. Pathologic CR was defined as the absence of tumor cells in the operative pathologic specimen, at the primary site, or in lymph node regions. The presence or absence of acellular mucin within the specimen was determined by review of operative pat...