Colorectal Cancer with Residual Polyp of Origin: A Model of Malignant Transformation

• Main Authors: Brooke R. Druliner, Shahrooz Rashtak, Xiaoyang Ruan, Taejeong Bae, Nikolaos Vasmatzis, Daniel O’Brien, Ruth Johnson, Donna Felmlee-Devine, Jill Washechek-Aletto, Nivedita Basu, Hongfang Liu, Thomas Smyrk, Alexej Abyzov, Lisa A. Boardman
• Format: Article
• Language: English
• Published: Elsevier 2016-08-01
• Series: Translational Oncology
• Online Access: http://www.sciencedirect.com/science/article/pii/S1936523316300833
• ISSN: 1936-5233; 1944-7124

The majority of colorectal cancers (CRCs) arise from adenomatous polyps. In this study, we sought to present the underrecognized CRC with the residual polyp of origin (CRC RPO+) as an entity to be utilized as a model to study colorectal carcinogenesis. We identified all subjects with biopsy-proven CRC RPO+ that were evaluated over 10 years at Mayo Clinic, Rochester, MN, and compared their clinical and pathologic characteristics to CRC without remnant polyps (CRC RPO−). Overall survival and disease-free survival overlap with an equivalent hazard ratio between CRC RPO+ and RPO− cases when age, stage, and grade are adjusted. The somatic genomic profile obtained by whole genome sequencing and the gene expression profiles by RNA-seq for CRC RPO+ tumors were compared with that of age -and gender-matched CRC RPO− evaluated by The Cancer Genome Atlas. CRC RPO+ cases were more commonly found with lower-grade, earlier-stage disease than CRC RPO−. However, within the same disease stage and grade, their clinical course is very similar to that of CRC RPO−. The mutation frequencies of commonly mutated genes in CRC are similar between CRC RPO+ and RPO− cases. Likewise, gene expression patterns are indistinguishable between the RPO+ and RPO− cases. We have confirmed that CRC RPO+ is clinically and biologically similar to CRC RPO− and may be utilized as a model of the adenoma to carcinoma transition.