Tomoki Tanaka

Permanent prostate brachytherapy with or without supplemental external beam radiotherapy as practiced in Japan: Outcomes of 1300 patients

PURPOSE To report outcomes for men treated with iodine-125 ((125)I) prostate brachytherapy (BT) at a single institution in Japan. METHODS AND MATERIALS Between 2003 and 2009, 1313 patients (median age, 68 years) with clinically localized prostate cancer were treated with (125)I BT. Median prostate-specific antigen level was 7.6 ng/mL (range, 1.1-43.3). T-stage was T1c in 60%, T2 in 39%, and T3 in 1% of patients. The Gleason score was <7, 7, and >7 in 49%, 45%, and 6% of patients, respectively. Neoadjuvant androgen deprivation therapy was used in 40% of patients and combined external beam radiotherapy of 45 Gy in 48% of patients. Postimplant dosimetry was performed after 30 days after implantation, with total doses converted to the biologically effective dose. Survival functions were calculated by the Kaplan-Meier method and Cox hazard model. RESULTS Median followup was 67 months (range, 6-126). The 7-year biochemical freedom from failure for low-, intermediate-, and selected high-risk prostate cancers were 98%, 93%, and 81%, respectively (p < 0.001). Multivariate analysis identified the Gleason score, initial prostate-specific antigen level, positive biopsy rate, dose, and neoadjuvant androgen deprivation therapy as predictors for biochemical freedom from failure. The 7-year actuarial developing Grade 3+ genitourinary and gastrointestinal toxicity was 2% and 0.3%, respectively. Forty-four percent patients with normal baseline potency retained normal erectile function at 5 years. CONCLUSIONS (125)I prostate BT is a highly effective treatment option for low-, intermediate-, and selected high-risk prostate cancers. Side effects were tolerable. An adequate dose may be required to achieve successful biochemical control.

Prostate‐specific antigen nadir within 12 months as an early surrogate marker of biochemical failure and distant metastasis after low‐dose‐rate brachytherapy or external beam radiotherapy for localized prostate cancer

Prostate‐specific antigen nadir (nPSA) after radiotherapy for localized prostate cancer has been investigated as a predictor. However, nPSA usually requires several years, limiting its clinical utility. We investigated the significance of nPSA within 12 months (nPSA12) after low‐dose‐rate prostate brachytherapy (LDR‐PB) or external beam radiotherapy (EBRT) on treatment outcomes. Between 2006 and 2014, 663 patients with prostate cancer were treated with LDR‐PB or EBRT at two institutions. Four hundred and seventy‐four men received LDR‐PB and 189 men received EBRT, without androgen deprivation therapy. The Kaplan–Meier method was used for biochemical failure (BF)‐free survival (BFFS) and distant metastasis (DM)‐free survival (DMFS) analyses, and multivariable Cox regression analysis was performed. The median follow‐up was 61.3 months. The median nPSA12 in the LDR‐PB and EBRT cohorts was 0.7 and 1.0 ng/mL, respectively. The 7‐year BFFS and DMFS rates in LDR‐PB patients with nPSA12 ≤ 0.7 ng/mL were 99.1% and 99.5%, respectively; when nPSA12 was >0.7 ng/mL, they were 90.2% and 94.8%, respectively. In EBRT patients with nPSA12 ≤ 1.0 ng/mL, BFFS and DMFS rates were 85.4% and 98.5%, respectively; when nPSA12 was >1.0 ng/mL, they were 67.1% and 87.2%, respectively. nPSA12 was an independent predictor of BF and DM in both cohorts (LDR‐PB, P = 0.004 and 0.020, respectively; EBRT, P = 0.005 and 0.041, respectively). The nPSA12 after LDR‐PB or EBRT is significantly associated with treatment outcomes of prostate cancer. Higher nPSA12 may identify patients at high risk of relapse who might benefit from salvage treatment.

Variations in Rectal Volumes and Dosimetry Values Including NTCP due to Interfractional Variability When Administering 2D-Based IG-IMRT for Prostate Cancer

We estimated variations in rectal volumes and dosimetry values including NTCP with interfractional motion during prostate IG-IMRT. Rectal volumes, DVH parameters, and NTCPs of 20 patients were analyzed. For this patient population, the median (range) volume on the initial plan for the rectum was 45.6 cc (31.3–82.0), showing on-treatment spread around the initial prediction based on the initial plan. DVH parameters of on-treatment CBCT analyses showed systematic regularity shift from the prediction based on the initial plan. Using the Lyman-Kutcher-Burman model, NTCPs of predicted late rectal bleeding toxicity of rectal grade ≥ 2 (RTOG) and the QUANTEC update rectal toxicity for the prediction based on the initial plan were 0.09% (0.02–0.24) and 0.02% (0.00–0.07), respectively, with NTCPs from on-treatment CBCT analyses being 0.35% (0.01–6.16) and 0.12% (0.00–4.11), respectively. Using the relative seriality model, for grade ≥ 2 bleeding rectal toxicity, NTCP of the prediction based on the initial plan was 0.64% (0.15–1.22) versus 1.48% (0.18–7.66) for on-treatment CBCT analysis. Interfraction variations in rectal volumes occur in all patients due to physiological changes. Thus, rectal assessment during 2D-based IG-IMRT using NTCP models has the potential to provide useful and practical dosimetric verification.

Mapping Prostate Biopsy Results following Continuous PSA Rises in Patients Treated with Iodine-125 Prostate Brachytherapy

on normalized EPIC QOL scores were used to compare clinical and dynamic changes over time between the two treatment groups (p!0.05). Results: Eighty-four and 125 patients were treated on the SBRT and HDR boost studies, with a median followup of 51 and 61 months, respectively. There were no significant differences in any of the domains at baseline between the two treatment groups (pO0.05). There was a significant difference in MCIC between treatments in the urinary (17% vs 58%, p! 0.0001) and sexual domains (50% vs 71%, p50.007) (figure 1). Overall, no significant difference was noted in the bowel domain (32% vs 44%, p50.25). Of patients who reported no problem with their sexual function at baseline, 6% and 23% respectively considered it to be a moderate to big problem on followup (p50.007). On univariate and multivariate analysis, higher baseline scores (ie. better QOL) predicted for greater chance of MCIC in the sexual domain (p!0.0001). Conclusions: Long-term followup data suggests that a greater percentage of patients with localized prostate cancer treated with HDR-boost reported deterioration of QOL particularly in sexual domains in comparison with SBRT alone. The relative contribution of the brachytherapy and external beam components of treatment to this is unknown.