Blood levels of miR-21, a piece of DNA known as microRNA, could serve as a promising biomarker for the early detection and prognosis of colorectal cancer, according to the results of a study published in the Journal of the National Cancer Institute.
Colorectal cancer remains the second leading cause of cancer-related death in the United States. More than 100,000 people in the United States are diagnosed with the disease each year and about 50,000 die from the disease. Researchers continue to investigate new methods of detecting the disease early when it is most treatable.
Although miR-21 and miR-31 (another microRNA) have been shown to negatively regulate tumor-suppressor genes, their potential as biomarkers for colorectal cancer has not yet been determined. In order to evaluate both of these microRNA, researchers screened blood samples from several hundred patients with either colorectal polyps (noncancerous growths that often precede cancer) or colorectal cancer or those who were part of the control group (and had neither cancer nor polyps).
The researchers found that miR-21 was secreted from colorectal cancer cell lines and upregulated in serum from colorectal cancer patients. Patients with polyps or colorectal cancer had a significantly elevated level of miR-21. What’s more, the levels dropped after curative surgery. Blood levels of miR-21 differentiated controls from patients with polyps or colorectal cancer. In fact, blood levels of miR-21 accurately identified approximately 92 percent of patients with colorectal cancer and 82 percent of those with advanced polyps. There was a significant correlation between high expression of miR-21 and tumor size, distant metastases, and poor survival.
The researchers concluded that miR-21 could serve as a promising biomarker for the early detection and prognosis of colorectal cancer. Right now, colonoscopy is the gold standard for colorectal cancer screening; however, less than half of those who should be screened are. A simple blood test could change the face of colorectal cancer screening and translate to more people being screened. Researchers will continue to evaluate miR-21 as a biomarker for this disease.
Toiyama Y, Takahashi M, Hur K, et al. Serum miR-21 as a diagnostic and prognostic biomarker in colorectal cancer. Journal of the National Cancer Institute. 2013; 105 (12): 849-859.