Room: ePoster Forums
Purpose: To assess the dosimetric coverage to dominant intraprostatic lesions (DILs) identified with multi-parametric MRI (mpMRI) as compared to those identified with SPECT/CT capromab pendetide for prostate seed implantation (PSI).
Methods: In 2007 our group published a study in which 239 patients underwent PSI for stage T1c-T3b prostate cancer with average Gleason-score: 6 and PSA:9ng/ml. SPECT/CT imaging was used to identify DILs that were dose escalated to 150% of prescription. Patients were treated with either Â¹Â²â?µI or Â¹â?°Â³Pd to a prescription dose of 144Gy or 125Gy for monotherapy, respectively; 110Gy or 100Gy for boost following EBRT of 45Gy. Recently (2006-2018), 113 patients received PSI for stage T1c-T3b prostate cancer with average Gleason-score: 7 and PSA:9.2ng/ml. These patients had at least one mpMRI identified DIL that was dose escalated to 150% of prescription. Isotope and prescription were the same as 2007â€™s study, except the Â¹Â²â?µI monotherapy dose was 145Gy. All the patients from the previous study and the current study were treated by the same physician in the same clinic. Post-operative dosimetric coverage to the SPECT/CT and mpMRI identified DILs as well as other dosimetric parameters were compared.
Results: SPECT/CT identified DILs had average DIL_V100% of 97.3Â±7.1% and DIL_V150% of 72.2Â±24.4%, as compared to DIL_V100% of 99.6Â±1.8% and DIL_V150% of 83.4Â±17.7% for mpMRI identified DILs. Prostate V100% was 88.1Â±8.2% in the previous study, whereas it was 93.4Â±4.3% in the current study. All these differences are statistically significant (p-value<0.001). Previous study didnâ€™t report rectum D2cc and urethra D10%. Comparing the current DIL group with 76 patients who didnâ€™t have a DIL, we found no significant increase in dose to rectum or urethra.
Conclusion: Dosimetric coverage of the prostate and DILs is significantly improved over the years (2007 vs 2018). No unusual acute toxicity has been observed; study on long-term outcome is warranted.
Not Applicable / None Entered.