Outcomes after PD-103 versus I-125 for low dose rate prostate brachytherapy monotherapy: An international, multi-institutional study

Chad Tang, Jeremiah Sanders, Howard Thames, David M. Swanson, Juanita M. Crook, Teresa Bruno, Pierre Blanchard, Jay Ciezki, Mira Keyes, Daniel Song, Tanmay Singh, Gregory Merrick, Richard Stock, Francis J. Sullivan, Henry Mok, Jeremy Millar, Steven J. Frank

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Abstract

Background and Purpose: Pd-103 and I-125 are commonly used in low dose rate (LDR) brachytherapy for prostate cancer. Comparisons of outcomes by isotope type are limited, but Pd-103 has distinct radiobiologic advantages over I-125 despite its lesser availability outside the United States. We evaluated oncologic outcomes after Pd-103 vs I-125 LDR monotherapy for prostate cancer. Materials and Methods: We retrospectively analyzed databases at 8 institutions for men who received definitive LDR monotherapy with Pd-103 (n = 1,597) or I-125 (n = 7,504) for prostate cancer. Freedom from clinical failure (FFCF) and freedom from biochemical failure (FFBF) stratified by isotope were analyzed by Kaplan-Meier univariate and Cox multivariate analyses. Biochemical cure rates (prostate-specific antigen level ≤ 0.2 ng/mL between 3.5 and 4.5 years of follow-up) by isotype were calculated for men with at least 3.5 years of follow-up and compared by univariate and multivariate logistic regression. Results: Compared with I-125, Pd-103 led to higher 7-year rates of FFBF (96.2% vs 87.6%, P < 0.001) and FFCF (96.5% vs 94.3%, P < 0.001). This difference held after multivariate adjustment for baseline factors (FFBF hazard ratio [HR] = 0.31, FFCF HR = 0.49, both P < 0.001). Pd-103 was also associated with higher cure rates on univariate (odds ratio [OR] = 5.9, P < 0.001) and multivariate (OR = 6.0, P < 0.001) analyses. Results retained significance in sensitivity analyses of data from the 4 institutions that used both isotopes (n = 2,971). Conclusions: Pd-103 monotherapy was associated with higher FFBF, FFCF, and biochemical cure rates, and suggests that Pd-103 LDR may lead to improved oncologic outcomes compared with I-125.

Original languageEnglish
Article number109599
Number of pages6
JournalRadiotherapy and Oncology
Volume183
DOIs
Publication statusPublished - Jun 2023
Externally publishedYes

Keywords

  • Brachytherapy
  • I-125
  • Low dose rate
  • Pd-103
  • Prostate Cancer

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