Document Type



Medicine and Health Sciences



During the multiyear progression to colorectal cancer, numerous genomic alterations arise in events ranging from single base mutations to gains or losses of entire chromosomes. A single genetic change might not stand out as an independent predictor of outcome. The goal of this study was to determine if more comprehensive measurements of genomic instability provide clinically relevant prognostic information.


Our study included 65 sporadic colorectal cancer patients diagnosed from 1987 to 1991 with last follow-up ascertained in 2006. We estimated an overall tally of alterations using the genome-wide sampling technique of inter-(simple sequence repeat [SSR]) polymerase chain reaction (PCR), and evaluated its relationship with all-cause survival. We also extended and sensitized the Bethesda criteria for microsatellite instability (MSI), by analyzing 348 microsatellite markers instead of the normal five. We expanded the MSI categories into four levels: MSI stable (MSS), very low-level MSI, moderately low-level MSI, and classical high-level MSI.


Tumors with genomic instability above the median value of 2.6% as measured by inter-SSR PCR, were associated with far greater risk of death compared to tumors with lower levels of genomic instability. Adverse outcome was most pronounced for patients presenting with stage 3 disease. A gradient of increased survival was observed across increasing MSI levels but did not reach statistical significance.


Our findings suggest genomic instabilities quantified by inter-SSR PCR and increased precision in MSI values may be clinically useful tools for estimating prognosis in colorectal cancer.


Ann Surg Oncol. Author manuscript; available in PMC 2012 June 19. Published in final edited form as: Ann Surg Oncol. 2012 January; 19(1): 344–350. Published online 2011 April 13. doi: 10.1245/s10434-011-1708-1 PMCID: PMC3378325 NIHMSID: NIHMS378305