Prognostic Impact and Metastasis Propensity of Grade Group 5 Prostate Cancer Following Permanent Seed Implantation Brachytherapy-Based Trimodality Therapy: Implications for Intensified Staging and Systemic Therapy Optimization.
To evaluate the prognostic impact of Grade Group (GG) 5 following permanent seed implantation brachytherapy-based trimodality therapy.
We retrospectively analyzed 352 men with National Comprehensive Cancer Network high-risk prostate cancer treated with trimodality therapy (low-dose-rate brachytherapy, external beam radiation therapy, and androgen deprivation therapy [ADT]) between 2003 and 2019. Staging included computed tomography, magnetic resonance imaging, and bone scintigraphy. Endpoints were biochemical recurrence (BCR; Phoenix definition), overall survival (OS), and cancer-specific survival (CSS). Survival outcomes were assessed using the Kaplan-Meier and log-rank tests. Multivariable Cox proportional hazards models, adjusting for prostate-specific antigen, clinical stage, duration of ADT, and biologically effective dose (BED), evaluated the association between GG5 and BCR. Clinical recurrence patterns post-BCR were assessed.
Median follow-up was 8.2 years (interquartile range [IQR] 5.4-10.0); median BED was 214 Gy (IQR 207-222). Among three study groups (GG1-3, GG4, and GG5), GG5 (n = 106) exhibited significantly lower BCR-free survival (p = 0.002) and CSS (p = 0.045), while OS was comparable (p = 0.3). GG5 remained an independent risk factor for BCR after the adjustment (vs. GG1-4, hazard ratio 2.78, 95% confidence interval 1.60-4.82, p < 0.001). GG5 recurrences predominantly involved the pelvic nodes or bone, whereas local and visceral metastases were infrequent.
This study demonstrated that GG5 is an independent predictor of BCR and cancer-specific mortality after trimodality therapy. Despite high BED, the propensity for nodal and bone metastases suggests the need for intensified staging and systemic therapy to optimize outcomes for GG5 disease.
We retrospectively analyzed 352 men with National Comprehensive Cancer Network high-risk prostate cancer treated with trimodality therapy (low-dose-rate brachytherapy, external beam radiation therapy, and androgen deprivation therapy [ADT]) between 2003 and 2019. Staging included computed tomography, magnetic resonance imaging, and bone scintigraphy. Endpoints were biochemical recurrence (BCR; Phoenix definition), overall survival (OS), and cancer-specific survival (CSS). Survival outcomes were assessed using the Kaplan-Meier and log-rank tests. Multivariable Cox proportional hazards models, adjusting for prostate-specific antigen, clinical stage, duration of ADT, and biologically effective dose (BED), evaluated the association between GG5 and BCR. Clinical recurrence patterns post-BCR were assessed.
Median follow-up was 8.2 years (interquartile range [IQR] 5.4-10.0); median BED was 214 Gy (IQR 207-222). Among three study groups (GG1-3, GG4, and GG5), GG5 (n = 106) exhibited significantly lower BCR-free survival (p = 0.002) and CSS (p = 0.045), while OS was comparable (p = 0.3). GG5 remained an independent risk factor for BCR after the adjustment (vs. GG1-4, hazard ratio 2.78, 95% confidence interval 1.60-4.82, p < 0.001). GG5 recurrences predominantly involved the pelvic nodes or bone, whereas local and visceral metastases were infrequent.
This study demonstrated that GG5 is an independent predictor of BCR and cancer-specific mortality after trimodality therapy. Despite high BED, the propensity for nodal and bone metastases suggests the need for intensified staging and systemic therapy to optimize outcomes for GG5 disease.
Authors
Matsuo Matsuo, Ozawa Ozawa, Yorozu Yorozu, Hattori Hattori, Kaneko Kaneko, Nakamura Nakamura, Yagi Yagi, Nishiyama Nishiyama, Saito Saito, Monma Monma
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