Biochemical outcomes and predictive factors by risk group after permanent iodine-125 seed implantation: Prospective cohort study in 2,316 patients

Norihisa Katayama; Katsumasa Nakamura; Atsunori Yorozu; Takashi Kikuchi; Masanori Fukushima; Shiro Saito; Takushi Dokiya

doi:10.1016/j.brachy.2019.03.008

Biochemical outcomes and predictive factors by risk group after permanent iodine-125 seed implantation: Prospective cohort study in 2,316 patients

Brachytherapy. 2019 Sep-Oct;18(5):574-582. doi: 10.1016/j.brachy.2019.03.008. Epub 2019 May 29.

Authors

Norihisa Katayama¹, Katsumasa Nakamura², Atsunori Yorozu³, Takashi Kikuchi⁴, Masanori Fukushima⁴, Shiro Saito⁵, Takushi Dokiya⁶

Affiliations

¹ Department of Radiology, Okayama University Medical School, Okayama, Japan. Electronic address: n-katayama@bea.hi-ho.ne.jp.
² Department of Radiation Oncology, Hamamatsu University School of Medicine, Hamamatsu, Japan.
³ Department of Radiation Oncology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.
⁴ Translational Research Informatics Center, Kobe, Japan.
⁵ Department of Urology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.
⁶ Department of Radiology, Kyoundo Hospital, Tokyo, Japan.

PMID: 31153759
DOI: 10.1016/j.brachy.2019.03.008

Abstract

Purpose: To evaluate the biochemical freedom from failure (bFFF) by risk group and treatment modality and the predictive factors of bFFF by risk group in patients with prostate cancer undergoing permanent seed implantation (PI) with or without external beam radiation therapy (EBRT) in a nationwide prospective cohort study (Japanese Prostate Cancer Outcome Study of Permanent Iodine-125 [I-125] Seed Implantation) in Japan during the first 2 years.

Methods and materials: The analyses included 2,316 participants in 42 institutions; bFFF was evaluated using the Phoenix definition and calculated using the Kaplan-Meier method, and the Cox proportional hazards model was used to identify the factors associated with bFFF.

Results: Median followup period was 60.0 months. The 5-year bFFF rates in all patients, 1,028 low-risk patients, 1,114 intermediate-risk patients, and 133 high-risk patients were 93.6%, 94.9%, 92.7%, and 91.1%, respectively. The 5-year bFFF rates in the PI group and EBRT combination therapy group were 93.7% and 93.3%, respectively. In a multivariate analysis, younger age, higher Gleason score (GS), higher percent positive biopsies (%PB), and lower prostate V₁₀₀ (p = 0.0012, 0.0030, 0.0026, and 0.0368) in all patients; younger age, higher pretreatment prostate-specific antigen, and lower prostate V₁₀₀ (p = 0.0002, 0.0048, and 0.0012) in low-risk patients; higher GS, higher %PB, and no hormonal treatment (p = 0.0005, 0.0120, and 0.0022) in intermediate-risk patients; and higher GS and higher %PB (p = 0.0329 and 0.0120) in high-risk patients were significantly associated with bFFF.

Conclusions: PI with or without EBRT resulted in excellent short-term biochemical outcomes in all risk groups, especially in high-risk patients. Age, pretreatment prostate-specific antigen, and prostate V₁₀₀ in low-risk patients; GS, %PB, and hormonal treatment in intermediate-risk patients; and GS and %PB in high-risk patients were independently affected bFFF.

Keywords: Biochemical failure; Brachytherapy; External beam radiation therapy; Predictive factors; Prostate cancer; Risk group.

Publication types

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

MeSH terms

Age Factors
Aged
Aged, 80 and over
Biopsy
Brachytherapy / methods*
Humans
Iodine Radioisotopes / therapeutic use*
Kallikreins / blood
Kaplan-Meier Estimate
Male
Middle Aged
Neoplasm Grading
Proportional Hazards Models
Prospective Studies
Prostate / pathology
Prostate-Specific Antigen / blood
Prostatic Neoplasms / blood
Prostatic Neoplasms / pathology
Prostatic Neoplasms / radiotherapy*
Risk Factors

Substances

Iodine Radioisotopes
KLK3 protein, human
Kallikreins
Prostate-Specific Antigen
Iodine-125