Biomarkers Could Lead to Early Diagnosis of Colorectal Cancer

An understanding of early genetic and epigenetic changes in colorectal cancer would aid in diagnosis and prognosis for patients suffering from this disease.

Genetic changes have been identified in the colon lining, or mucosa, in colorectal cancer patients that could be used as biomarkers of the disease and that will allow doctors to diagnose patients earlier, more accurately and less invasively.

Scientists at the McGill University Health Center (Montreal, QC, Canada) collected biologic specimens from patients undergoing colon resection for presumed or biopsy-proven colon cancers and also biologic specimens from subjects undergoing routine screening colonoscopy for control specimens.

Ribonucleic acid (RNA) was extracted, and prepared biologic replicates were used to confirm microarray results by quantitative real-time polymerase chain reaction (qRT-PCR) and verify effects of genotype and diet on expression. Microarray studies were performed using Affymetrix Mouse Gene 1.0 ST Array Chips (Santa Clara, CA, USA) and quantitative cytosine, phosphate, guanine (CpG) methylation analysis was performed by pyrosequencing.

The investigators identified five possible abnormal marker genes in a colon cancer-mouse model. They then confirmed that these candidate biomarker genes were also abnormal in tissue obtained from colon cancer patients. Interestingly, the abnormal patterns of these genes were detected in otherwise normal colon cells that were not near the tumor site. DNA-based biomarkers in normal colonic mucosa would be extremely useful because they have the potential to be diagnostic of colon cancer in the near term or, upon further development, may become prognostic indicators of colon cancer risk. Such biomarkers would provide discriminatory and quantitative biochemical measures to supplement the current endoscopic screening test that is both invasive and subjective.

Rima Rozen, PhD, a geneticist and senior author of the study said, “This new method could help to avoid false negative findings, which can occur in 10% to 15% of endoscopic procedures. The key is using the right genes. I believe the ones we have identified are good candidates. Our finding suggests that it may be possible to take tissue samples in more accessible regions of the gastrointestinal tract or, ideally, in blood or stool, and look for biomarkers as an early indicator of disease." The study was published on November 3, 2013, in the journal Cancer Prevention Research.

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