Multiparametric MRI and post implant CT-based dosimetry after prostate brachytherapy with iodine seeds: The higher the dose to the dominant index lesion, the lower the PSA bounce. Issue 2 (November 2015)

• Record Type: Journal Article
• Authors: Quivrin, Magali; Loffroy, Romaric; Cormier, Luc; Mazoyer, Frédéric; Bertaut, Aurélie; Chambade, Damien; Martin, Etienne; Maingon, Philippe; Walker, Paul; Créhange, Gilles
• Is Part Of: Radiotherapy and oncology. Volume 117:Issue 2(2015:Nov.)
• Page Start: 258
• Page End: 261
• Publication Date: 2015-11
• Subjects: Prostate -- Brachytherapy -- Iodine seeds -- PSA bounce -- MRI -- Dosimetry; Oncology -- Periodicals; Radiotherapy -- Periodicals; Tumors -- Periodicals; Medical Oncology -- Periodicals; Neoplasms -- radiotherapy -- Periodicals; Radiotherapy -- Periodicals; Radiothérapie -- Périodiques; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9940642
• DOI: 10.1016/j.radonc.2015.08.020
• Languages: English
• ISSNs: 0167-8140

Abstract

Abstract: Purpose: To determine whether post-implant MRI-based dosimetry of the Dominant Intra-prostatic Lesion (DIL) could best predict the occurrence of PSA bounce after prostate brachytherapy. Methods and materials: We selected 66 patients with a low risk prostate cancer treated with 125 I prostate brachytherapy as monotherapy. Post-implant dosimetry based on day 30 CT-scan and multiparametric MRI co-registration was generated: planned D 90, D 95, V 100, V 150 values were calculated for each DIL. Bounce was defined as a PSA elevation ⩾0.2 ng/mL from the previous baseline value followed by a decrease to or below the prior nadir with no additional treatment. Results: After a median follow-up of 35.5 months (range 13.2–72.5), a PSA bounce occurred in 24 (36.4%) patients. The mean planned D 90 of the DIL was significantly lower in bouncers: 196 ± 61 Gy vs. 234 ± 62 Gy, p = 0.018. The mean planned V 150 of the DIL was 56 ± 32% for bouncers while it was 75 ± 30% for non-bouncers, p = 0.026. Conclusion: A lower planned D 90 or V 150 in the DIL were predictive of PSA bounce after prostate brachytherapy. PSA bounce could be caused by delayed cell death related to sublethal damage accumulation in the tumor.