Molecular Genetic Characteristics of Colorectal Cancer in Patients 90 Years and Older Differ from the Findings in Younger Patients

Abstract

Aim: Only limited information is available on the molecular characteristics of colorectal cancers diagnosed in patients 90 years and older. There are indirect suggestions that in cancers from very elderly patients, molecular genetic changes may be either more, or less prevalent; thus, raising the question as to the similarity in genetic changes found in colorectal cancers between very elderly and younger patients. We examined several molecular changes associated with colorectal cancers in 41 very elderly patients, and compared the results to the findings of a younger cohort, between ages 55 and 79 years. Methods: We evaluated MSI, loss of heterozygosity for APC and DCC genes, KRAS and BRAF gene mutations, and DNA methylation in colon cancer tissue samples using standard PCR techniques. Results: our data indicate that colorectal cancers from very elderly patients are more frequently right-sided and more likely to demonstrate microsatellite instability. If the cancers contain a KRAS mutation, it is less likely to be in the second codon position. Finally, KRAS 61 may be more frequent in the very elderly. Conclusions: Overall, the colorectal cancers from our very elderly patients, 90 years and older, have at least as many, if not more, molecular genetic changes than the cancers from younger.