Next-Generation Sequencing of Matched Primary and Metastatic Rectal Adenocarcinomas Demonstrates Minimal Mutation Gain and Concordance to Colonic Adenocarcinomas.

Context.—Colorectal carcinoma is the third most common cause of cancer death in males and females in the United States. Rectal adenocarcinoma can have distinct therapeutic and surgical management from colonic adenocarcinoma owing to its location and anatomic considerations. Objective.—To determine the oncologic driver mutations and better understand the molecular pathogenesis of rectal adenocarcinoma in relation to colon adenocarcinoma. Design.—Next-generation sequencing was performed on 20 cases of primary rectal adenocarcinoma with a paired lymph node or solid organ metastasis by using an amplicon-based assay of more than 2800 Catalogue of Somatic Mutations in Cancer (COSMIC)–identified somatic mutations. Results.—Next-generation sequencing data were obtained on both the primary tumor and metastasis from 16 patients. Most rectal adenocarcinoma cases demonstrated identical mutations in the primary tumor and metastasis (13 of 16, 81%). The mutations identified, listed in order of frequency, included TP53,...