Urethral toxicity after LDR brachytherapy: experience in Japan

Duration of α-1 adrenergic antagonist administration after low-dose-rate brachytherapy for prostate cancer

BACKGROUND

Urinary dysfunction is an adverse event of low-dose-rate brachytherapy (LDR-BT) in patients with prostate cancer. We aimed to examine the time to α-1 adrenergic antagonist withdrawal after LDR-BT initiation.

METHODS

We retrospectively evaluated 1663 patients who underwent LDR-BT at our hospital during 2004-2022.

RESULTS

Overall, 1485/1663 (89.3%) patients were able to stop using α-1 adrenergic antagonists, 1111 (66.8%) of them within 1 year of LDR-BT. Risk factors for prolonged time to withdrawal were age ≥70 years, taking agents for lower urinary tract symptoms prior to LDR-BT, an International Prostate Symptom Score ≥8, an Overactive Bladder Symptom Score ≥3 and a residual urine volume ≥20 ml. Of the patients who were able to stop taking α-1 adrenergic antagonists, 357/1485 (24.0%) required resumption, 218 (61.1%) of whom did so between 1 and 3 years after LDR-BT. This period matched the period of transient worsening of the urinary symptom score. Finally, multivariable analysis identified supplemental external beam radiotherapy and an Overactive Bladder Symptom Score ≥3 as independent risk factors for α-1 adrenergic antagonist resumption.

CONCLUSIONS

Withdrawal of α-1 adrenergic antagonists was possible in 66.8% of patients within 1 year of LDR-BT. Our results suggest that patients who are older or have pre-treatment LUTS may have prolonged deterioration of urinary dysfunction after treatment. Resumption of α-1 adrenergic antagonists 1-3 years after treatment may be associated with urinary symptom flares, and close attention is necessary for patients with supplemental external beam radiotherapy and a high pretreatment Overactive Bladder Symptom Score.

Acute and late side-effects after low dose-rate brachytherapy for prostate cancer; incidence, management and technical considerations

PURPOSE

To review common reported side effects and complications after primary LDR-BT (monotherapy) and discuss some of the technical aspects that could impact the treatment outcomes.

METHODS AND MATERIALS

A literature search was undertaken using medical subject headings (MeSH) complemented by the authors' personal and institutional expertise.

RESULTS

The reported incidence of acute and late grade 2 or above urinary, bowel and sexual side effects is very variable across the literature. The learning curve and the implant quality have a clear impact on the toxicity outcomes. Being aware of some of the technical challenges encountered during the procedure and ways to mitigate them could decrease the incidence of side effects. Careful planning of seed placement and seed deposition allow sparing of the organs at risk and a lower incidence of urinary and gastro-intestinal toxicity.

CONCLUSIONS

Low dose-rate brachytherapy remains a standard monotherapy treatment in the setting of favorable-risk prostate cancer. High disease control and low long-term toxicities are achievable in expert hands with a good technique.

A prospective study of oral 5-aminolevulinic acid to prevent adverse events in patients with localized prostate cancer undergoing low-dose-rate brachytherapy: Protocol of the AMBER study

Background

Radiotherapy is one of the most frequently selected treatment options for patients with prostate cancer. However, adverse effects related to the irradiated surrounding normal organs are significant clinical concerns. Specifically, genitourinary and gastrointestinal toxicities can lead to a dramatically reduced quality of life. The aim of this clinical trial is to determine the efficacy of oral 5-aminolevulinic acid (ALA) phosphate with sodium ferrous citrate (SFC) in patients treated with low-dose-rate brachytherapy (LDR-BT) using an iodine-125 seed source.

Methods

The AMBER study is a prospective, single-center trial in patients with localized prostate cancer undergoing LDR-BT. Patients who undergo supplementary extra-beam radiotherapy are excluded, whereas those who undergo pre-implantation short-term (4–6 months) androgen deprivation therapy to decrease the prostate volume and/or improve oncological outcomes are included. After the screening and registration, the patients will be instructed to take capsules of ALA-SFC twice a day (200 mg and 229.42 mg per day) for 6 months from the day of seed implantation (prescribed radiation dose of 160 Gy). Patient data will be collected before the implantation; during oral ALA-SFC treatment; and 1, 3, 6, 9, and 12 month(s) after seed implantation. The primary endpoint of this trial is the urinary frequency 3 months after seed implantation. At each visit, the 24-h urinary frequency, total voided volume, and mean voided volume on a frequency volume chart and other patient-reported outcomes are recorded. The data of the trial cases will be compared with those of historical controls, who are consecutive patients undergoing LDR-BT without supplementary extra-beam radiotherapy between January 2016 and January 2019. The number of subjects has been set to be 50 for trial cases and 150 for the historical control cases. Pre- and post-treatment clinicopathologic factors are compared between two groups.

Discussion

The goal of this trial is to determine the potential benefit of ALA-SFC in patients who undergo LDR-BT. To the best of our knowledge, this is the first study investigating the potential clinical benefit of oral ALA-SFC after radiotherapy. More evidence from a further randomized controlled trial is needed to change the standard of care and lead to better post-radiotherapy management.

Trial registration

This clinical trial was prospectively registered with the Japan Registry of Clinical Trials on 5 December 2019. The reference number is jRCTs051190077, nara0013 (Certified Review Board of Nara Medical University).

First-passage times and normal tissue complication probabilities in the limit of large populations

The time of a stochastic process first passing through a boundary is important to many diverse applications. However, we can rarely compute the analytical distribution of these first-passage times. We develop an approximation to the first and second moments of a general first-passage time problem in the limit of large, but finite, populations using Kramers–Moyal expansion techniques. We demonstrate these results by application to a stochastic birth-death model for a population of cells in order to develop several approximations to the normal tissue complication probability (NTCP): a problem arising in the radiation treatment of cancers. We specifically allow for interaction between cells, via a nonlinear logistic growth model, and our approximations capture the effects of intrinsic noise on NTCP. We consider examples of NTCP in both a simple model of normal cells and in a model of normal and damaged cells. Our analytical approximation of NTCP could help optimise radiotherapy planning, for example by estimating the probability of complication-free tumour under different treatment protocols.

A stochastic model for the normal tissue complication probability (NTCP) and applicationss

The normal tissue complication probability (NTCP) is a measure for the estimated side effects of a given radiation treatment schedule. Here we use a stochastic logistic birth-death process to define an organ-specific and patient-specific NTCP. We emphasize an asymptotic simplification which relates the NTCP to the solution of a logistic differential equation. This framework is based on simple modelling assumptions and it prepares a framework for the use of the NTCP model in clinical practice. As example, we consider side effects of prostate cancer brachytherapy such as increase in urinal frequency, urinal retention and acute rectal dysfunction.

Dosimetry advantages of intraoperatively built custom-linked seeds compared with loose seeds in permanent prostate brachytherapy

Purpose

The aim of this study was to compare the implant quality between intraoperatively built custom-linked seeds (IBCL) and loose seeds (LS) retrospectively.

Material and methods

This study included 74 prostate cancer patients who were treated with permanent prostate brachytherapy (PPB) using IBCL (n = 37) or LS (n = 37) between July 2014 and June 2016. Dose-volume histogram (DVH) parameters, seed migration, and operation time were compared between the IBCL and LS groups. In addition to the standard target volume of the whole prostate gland, DVH parameters for prostate plus a 3 mm margin (CTV) were evaluated.

Results

In intraoperative planning, prostate V₁₅₀ was lower (54.8% vs. 59.6%, p = 0.027), and CTV V₁₀₀ (88.1% vs. 85.6%, p = 0.019) and D₉₀ (98.5% vs. 92.6%, p = 0.0033) were higher in the IBCL group compared with in the LS group. In post-implant dosimetry, prostate V₁₀₀ (96.9% vs. 95.2%, p = 0.020), CTV V₁₀₀ (85.6% vs. 81.7%, p = 0.046), and CTV D₉₀ (94.2% vs. 86.5%, p < 0.001) were higher, and prostate V₁₅₀ (57.1% vs. 64.5%, p = 0.0051) and CTV V₁₅₀ (31.5% vs. 35.7%, p = 0.046) were lower in the IBCL group compared with in the LS group. Regarding DVH changes between intraoperative planning and post-implant dosimetry, the decrease in prostate D₉₀ was significantly lower in the IBCL group than in the LS group (–1.16% vs. –4.17%, p < 0.001). For the IBCL group, the operation time was slightly but significantly longer than that for the LS group (50.5 minutes vs. 43.7 minutes, p = 0.011). However, the seed migration rate was significantly lower in the IBCL group than in the LS group (5% vs. 41%, p < 0.001).

Conclusions

Intraoperatively built custom-linked is more advantageous than LS in terms of dosimetric parameters and migration.

Stereotactic Body Radiotherapy versus Low Dose Rate Brachytherapy for Localised Prostate Cancer: a Cost-Utility Analysis

AIMS

To conduct a cost-utility analysis comparing stereotactic body radiotherapy (SBRT) with low dose rate brachytherapy (LDR-BT) for localised prostate cancer (PCa).

MATERIALS AND METHODS

A decision-analytic Markov model was developed from the healthcare payer perspective to simulate the history of a 66-year-old man with low-risk PCa. The model followed patients yearly over their remaining lifetimes. Health states included 'recurrence-free', 'biochemical recurrence' (BR), 'metastatic' and 'death'. Transition probabilities were based on a retrospective cohort analysis undertaken at our institution. Utilities were derived from the literature. Costs were assigned in 2015 Canadian dollars ($) and reflected Ontario's health system and departmental costs. Outcomes included quality-adjusted life years (QALYs), costs and incremental cost-effectiveness ratios. A willingness-to-pay threshold of $50 000/QALY was used.

RESULTS

SBRT was the dominant strategy with 0.008LYs and 0.029QALYs gained and a reduction in cost of $2615. Under base case conditions, our results were sensitive to the BR probability associated with both strategies. LDR-BT becomes the preferred strategy if the BR with SBRT is 1.3*[baseline BR_SBRT] or if the BR with LDR-BT is 0.76*[baseline BR_LDR-BT]. When assuming the same BR for both strategies, LDR-BT becomes marginally more effective with 0.009QALYs gained at a cost of $272 848/QALY.

CONCLUSIONS

SBRT represents an economically attractive radiation strategy. Further research should be carried out to provide longer-term follow-up and high-quality evidence.

Assessment of lower urinary symptom flare with overactive bladder symptom score and International Prostate Symptom Score in patients treated with iodine-125 implant brachytherapy: long-term follow-up experience at a single institute

Background

The aim of this study was to evaluate the combined use of the overactive bladder symptom score (OABSS) and International Prostate Symptom Score (IPSS) as an assessment tool for urinary symptom flare after iodine-125 (¹²⁵I) implant brachytherapy. The association between urinary symptom flare and prostate-specific antigen (PSA) bounce was investigated.

Methods

Changes in the IPSS and OABSS were prospectively recorded in 355 patients who underwent seed implantation. The percentage distribution of patients according to the difference between the flare peak and post-implant nadir was plotted to define significant increases in the scores. The clinicopathologic characteristics, treatment parameters, and post-implant dosimetric parameters were compared between the non-flare and flare groups. PSA bounce was defined as an elevation of ≥0.1 ng/mL or ≥0.4 ng/mL compared to the previous lowest value, followed by a decrease to a level at or below the pre-bounce value.

Results

A clinically significant increase required an IPSS increase of at least 12 points and an OABSS increase of at least 6 points based on a time-course analysis of total scores and the QOL index. Assessment only by IPSS failed to detect 40 patients (11%) who had urinary symptom flare according to the OABSS. Univariate and multivariate analyses revealed that patients treated with higher biologically effective doses and those without diabetes mellitus had higher risks of urinary flare. There was no statistical correlation between the incidence and time of urinary symptom flare onset and that of a PSA bounce.

Conclusions

To our knowledge, this is the first report to prove the clinical potential of the OABSS as an assessment tool for urinary symptom flare after seed implantation. Our findings showed that persistent lower urinary tract symptoms after seed implantation were attributed to storage rather than to voiding issues. We believe that assessment with the OABSS combined with the IPSS would aid in decision-making in terms of timing, selection of a treatment intervention, and assessment of the outcome.

Electronic supplementary material

The online version of this article (doi:10.1186/s12894-017-0251-1) contains supplementary material, which is available to authorized users.