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

Magali Quivrin; Romaric Loffroy; Luc Cormier; Frédéric Mazoyer; Aurélie Bertaut; Damien Chambade; Etienne Martin; Philippe Maingon; Paul Walker; Gilles Créhange

doi:10.1016/j.radonc.2015.08.020

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

Radiother Oncol. 2015 Nov;117(2):258-61. doi: 10.1016/j.radonc.2015.08.020. Epub 2015 Aug 28.

Authors

Affiliations

¹ Department of Radiation Oncology, Georges François Leclerc Cancer Center, Dijon, France; Medical Imaging Group, Laboratory of Electronics, Computer Science and Imaging (Le2I), CNRS 6306, University of Burgundy, France.
² Medical Imaging Group, Laboratory of Electronics, Computer Science and Imaging (Le2I), CNRS 6306, University of Burgundy, France; Department of Radiology, University Hospital Le Bocage, Dijon, France.
³ Department of Urology, University Hospital Le Bocage, Dijon, France.
⁴ Department of Medical Physics and Radiation Oncology, Georges François Leclerc Cancer Center, Dijon, France.
⁵ Department of Biostatistics, Georges François Leclerc Cancer Center, Dijon, France.
⁶ Department of Surgery, Georges François Leclerc Cancer Center, Dijon, France.
⁷ Department of Radiation Oncology, Georges François Leclerc Cancer Center, Dijon, France.
⁸ Medical Imaging Group, Laboratory of Electronics, Computer Science and Imaging (Le2I), CNRS 6306, University of Burgundy, France; Department of MR Spectroscopy, University Hospital Le Bocage, Dijon, France.
⁹ Department of Radiation Oncology, Georges François Leclerc Cancer Center, Dijon, France; Medical Imaging Group, Laboratory of Electronics, Computer Science and Imaging (Le2I), CNRS 6306, University of Burgundy, France. Electronic address: [email protected].

PMID: 26324019
DOI: 10.1016/j.radonc.2015.08.020

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 D90, D95, V100, V150 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 D90 of the DIL was significantly lower in bouncers: 196 ± 61 Gy vs. 234 ± 62 Gy, p = 0.018. The mean planned V150 of the DIL was 56 ± 32% for bouncers while it was 75 ± 30% for non-bouncers, p = 0.026.

Conclusion: A lower planned D90 or V150 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.

Keywords: Brachytherapy; Dosimetry; Iodine seeds; MRI; PSA bounce; Prostate.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aged
Brachytherapy*
Follow-Up Studies
Humans
Iodine Radioisotopes / therapeutic use*
Magnetic Resonance Imaging / methods*
Male
Middle Aged
Prostate / diagnostic imaging
Prostate / pathology
Prostate-Specific Antigen / radiation effects*
Prostatic Neoplasms / radiotherapy
Radiometry
Radiotherapy Dosage
Retrospective Studies
Tomography, X-Ray Computed / methods*
Treatment Outcome

Substances

Iodine Radioisotopes
Prostate-Specific Antigen