Local tumor control and DNA-PK activity of peripheral blood lymphocytes in prostate cancer patients receiving radiotherapy

Repair of dna damage is critical for genomic stability,and dna-dependent protein kinase (dna-pk) has an important role in repairing double-strand breaks. we examined whether the dna-pk activity of peripheral blood lymphocytes (pbls) was related to biochemical (prostate-specific antigen: psa) relapse and radiation toxicity in prostate cancer patients who have received radiotherapy. a total of 69 patients with localized adenocarcinoma of the prostate participated in this study. peripheral blood was collected 2 years or later after radiotherapy and centrifuged,then dna-pk activity was measured by a filter binding assay. the high dna-pk activity group had a significantly higher psa relapse-free survival rate than the low dna-pk activity group. the 10-year psa relapse-free survival was 87.0% in the high dna-pk activity group,whereas it was 52.7% in the low dna-pk activity group. multivariate analysis showed the gleason score and the level of dna-pk activity were significant predictors of psa relapse after radiotherapy. in addition,the low dna-pk activity group tended to have a higher incidence of grade 1-2 urinary toxicity than the high dna-pk activity group. prostate cancer patients with low dna-pk activity had a higher rate of psa relapse and a higher incidence of urinary toxicity. dna-pk activity in pbls might be a useful marker for predicting psa relapse and urinary toxicity,possibly contributing to personalized treatment of prostate cancer. © the author 2016.