Measuring the genetic damage in cancer patients during radiotherapy with three genetic end-points

In this paper the genetic damage for three genetic end-points was studied in cancer patients during radiotherapy using the micronucleus test, comet assay and hprt gene mutation test. The subjects were from: (i) a group of 24 patients suffering from various types of cancers; (ii) a group of 23 controls matched according to age, sex and smoking. Blood samples were collected from the controls and from the cancer patients prior to radiotherapy and after cumulative radiation doses of 10, 30 and 50 Gy. The results of the micronucleus test indicated that the mean micronuclei rate (MNR) and mean micronucleated cells rate (MCR) in the cancer patients prior to radiotherapy were 12.46 and 11.29 per thousand, respectively, which were significantly higher than those (6.65 and 5.96 per thousand) in controls (P < 0.01). However, the results of the comet assay and hprt gene mutation test showed no significant difference between untreated cancer patients and controls (P > 0.05). The mean MNR/MCR at 0, 10, 30 and 50 Gy in cancer patients increased with the cumulative dose, being 12.46, 35.83, 64.63 and 85.00 per thousand for MNR and 11.29, 31.25, 53.63 and 67.28 per thousand for MCR, respectively. Similar results were obtained in the comet assay and hprt gene mutation test. Meanwhile, it was found that there was inter-individual variability in response to radiotherapy among patients.