Impact of a dominant intraprostatic lesion (DIL) boost defined by sextant biopsy in permanent I-125 prostate implants on biochemical disease free survival (bDFS) and toxicity outcomes.

Abstract

BACKGROUND AND PURPOSE\nTo compare bDFS and toxicity outcomes in a population of intermediate risk prostate cancer patients treated using I-125 LDR brachytherapy with or without DIL boost based on multiple core biopsy maps.\n\n\nMATERIALS AND METHODS\nBetween January 2005 and December 2013, all our intermediate risk prostate cancer patients treated with LDR I-125 brachytherapy were reviewed. All patients were given 144\u202fGy to the prostate. A pathologic DIL distribution (defined by sextant biopsy) was contoured prospectively prior to planning, to be covered by the 150% isodose line. Of the 165 patients treated, 55 received a DIL boost. Patients completed prospectively the IPSS questionnaire, a sexual and bowel function questionnaire. Gastro-intestinal toxicities were graded according to CTCAE v4.03. A patient was considered to have erectile dysfunction if he was unable to achieve erection to perform intercourse. BDFS was determined according to the Phoenix consensus definitions.\n\n\nRESULTS\nThe median follow-up was 78\u202fmonths. The estimated 7-year bDFS rate was 96% (95% CI, 74-99%) in the DIL group versus 89% (95% CI, 79-94%) in the control group (p\u202f=\u202f0.188). There was no difference between groups in urinary, gastro-intestinal or sexual toxicities up to 5\u202fyears of follow-up. There was no difference in urinary obstruction with catheterization between DIL versus control groups (3,6 vs 2,8 %, p\u202f=\u202f1.00). Only 1 patient in the DIL group had ≥grade 3 toxicity (TURP) and none in the control group.\n\n\nCONCLUSIONS\nBoost to DIL defined by sextant biopsy with permanent seed prostate implant shows a trend toward improvement of biochemical control in intermediate risk prostate cancer patient without increasing toxicity.