Micronucleus frequency in human peripheral blood lymphocytes as a biomarker for the early detection of colorectal cancer risk.

The early detection of colorectal cancer (CRC) can significantly improve the prognosis of affected patients. The loss of genomic stability and the resulting gene alteration play an important role in the molecular pathological steps that occur early in tumorigenesis of CRC. Thus, the identification of non-invasive biomarkers, whose function may provide useful insights into critical early events in the CRC process, is of great interest. In this regard, micronucleus (MN) frequency in peripheral blood lymphocytes (PBL) has become one of the most established biomarkers for studying DNA damage in the human population. This study investigated the MN frequency in the PBL of 82 subjects (30 females and 52 males; aged 50-70 years) who were participating in a screening programme for CRC prevention. All 82 patients were positive in fecal occult blood tests and they were subsequently classified, according to colonoscopy and histological findings, as patients with CRC, patients with colon polyps or subjects without intestinal lesion, referred to as study controls. This study also examined the relationship between the plasma clastogenic activity and the frequency of micronuclei of the study population. The MN frequency was significantly higher in CRC patients than in both colon polyp patients (16.82±6.56 versus 12.23±1.88; P = 0.002) and controls (16.82±6.56 versus 8.00±1.77; P < 0.001). An increased MN frequency was detected in the lymphocytes of the polyp group in comparison to the control group, although this was lower than that observed in CRC patients (12.23±1.88 versus 8.00±1.77; P < 0.001). In the overall study population, the increase of MN frequency, which was observed in the lymphocytes of the subjects involved, was significantly associated with the clastogenic activity detected in their plasma (r = 0.594, P < 0.001). Overall, the results suggest that the MN test can become a promising biomarker for the early detection of CRC.