Can serum Glutathione-S-transferase levels in carcinoma cervix be a predictor of radiation response?

We conducted a pilot study wherein serum Glutathione-S-transferase levels were measured before and after radiotherapy in carcinoma cervix patients and correlated with response to treatment during a two-year follow-up period. Out of 17 patients who received radiotherapy, 9 showed a significant decrease (p<0.005) while 8 showed significant increase (p<0.004) in post radiotherapy glutathione-S-transferase values as compared to pre treatment values respectively. These patients were followed up for two years and we observed that 71% who had significant increase in post radiotherapy values had relapse of cancer within 2 years where as 66% of those who had significant decrease in post radiotherapy values had no evidence of relapse. This shows that alterations in serum Glutathione-S-transferase levels may help us to predict radiation response.