Catheter displacement prior to the delivery of high-dose-rate brachytherapy in the treatment of prostate cancer patients

Therapeutic prostate cancer interventions: a systematic review on pubic arch interference and needle positioning errors

INTRODUCTION

This study focuses on the quantification of and current guidelines on the hazards related to needle positioning in prostate cancer treatment: (1) access restrictions to the prostate gland by the pubic arch, so-called Pubic Arch Interference (PAI) and (2) needle positioning errors. Next, we propose solution strategies to mitigate these hazards.

METHODS

The literature search was executed in the Embase, Medline ALL, Web of Science Core Collection*, and Cochrane Central Register of Controlled Trials databases.

RESULTS

The literature search resulted in 50 included articles. PAI was reported in patients with various prostate volumes. The level of reported PAI varied between 0 and 22.3 mm, depending on the patient's position and the measuring method. Low-Dose-Rate Brachytherapy induced the largest reported misplacement errors, especially in the cranio-caudal direction (up to 10 mm) and the largest displacement errors were reported for High-Dose-Rate Brachytherapy in the cranio-caudal direction (up to 47 mm), generally increasing over time.

CONCLUSIONS

Current clinical guidelines related to prostate volume, needle positioning accuracy, and maximum allowable PAI are ambiguous, and compliance in the clinical setting differs between institutions. Solutions, such as steerable needles, assist in mitigating the hazards and potentially allow the physician to proceed with the procedure.This systematic review was performed in accordance with the PRISMA guidelines. The review was registered at Protocols.io (DOI: dx.doi.org/10.17504/protocols.io.6qpvr89eplmk/v1).

In vivo dosimetry in pelvic brachytherapy

ADVANCES IN KNOWLEDGE

This paper describes the potential role for in vivo dosimetry in the reduction of uncertainties in pelvic brachytherapy, the pertinent factors for consideration in clinical practice, and the future potential for in vivo dosimetry in the personalisation of brachytherapy.

High dose rate brachytherapy for prostate cancer: A prospective toxicity evaluation of a one day schedule including two 13.5 Gy fractions

BACKGROUND AND PURPOSE

High dose-rate (HDR) brachytherapy (BT) provides a highly conformal method of dose delivery to the prostate. The purpose of this study is to prospectively determine the toxicity of the treatment protocol of 13.5 Gy × 2 fractions.

MATERIALS AND METHODS

From 2010 through 2017, 119 patients with low (71%) or intermediate-risk prostate cancer were prospectively treated in a single institute with HDR-BT at 13.5 Gy × 2 fractions within one day. Median follow-up time was 4.4 years.

RESULTS

Actuarial rates of no biochemical evidence of disease, overall survival and metastasis-free survival for all patients were 96%,98% and 98%, respectively. The cumulative incidence of acute grade 2 and 3 genitourinary (GU) toxicity was 9% and 2%, respectively. The corresponding incidences of late GU toxicity were 18% and 1%. No grade ≥4 of either type of toxicity was detected. Multivariate analysis showed that having higher international prostate symptom score (IPSS; P = 0.041) or higher V₂₀₀ (P = 0.013) was associated with a higher risk of experiencing any grade of acute GU toxicity. In addition, patients having a higher IPSS (P = 0.019) or a higher V₁₅₀ (P = 0.033) were associated with a higher grade >1 acute GU toxicity.

CONCLUSIONS

The findings of this study show that HDR-BT 13.5 Gy × 2 as monotherapy was safe and effective for prostate cancer patients with low-intermediate risk.

Biological imaging for individualized therapy in radiation oncology: part I physical and technical aspects

Recently, there has been an increase in the imaging modalities available for radiotherapy planning and radiotherapy prognostic outcome: dual energy computed tomography (CT), dynamic contrast enhanced CT, dynamic contrast enhanced magnetic resonance imaging (MRI), diffusion-weighted MRI, positron emission tomography-CT, dynamic contrast enhanced ultrasound, MR spectroscopy and positron emission tomography-MR. These techniques enable more precise gross tumor volume definition than CT alone and moreover allow subvolumes within the gross tumor volume to be defined which may be given a boost dose or an individual voxelized dose prescription may be derived. With increased plan complexity care must be taken to immobilize the patient in an accurate and reproducible manner. Moreover the physical and technical limitations of the entire treatment planning chain need to be well characterized and understood, interdisciplinary collaboration ameliorated (physicians and physicists within nuclear medicine, radiology and radiotherapy) and image protocols standardized.

Dosimetric impact of inter-observer catheter reconstruction variability in ultrasound-based high-dose-rate prostate brachytherapy

PURPOSE

To investigate the dosimetric impact of interobserver catheter reconstruction variability in transrectal ultrasound-guided prostate high-dose-rate (HDR) brachytherapy.

METHODS AND MATERIALS

Twenty consecutive patients with intermediate- or high-risk prostate cancer were treated with a single, 15-Gy HDR brachytherapy boost as part of this study. The treated plan was used as the study reference plan (P_R). Three expert treatment planners (observers) manually reconstructed the catheter paths on the static three-dimensional transrectal ultrasound images, and new plans were generated from the updated positions (P_OBS); subsequently, the dwell time and positions from the P_OBS plans were superimposed on the P_R catheter paths to evaluate the dosimetric effect of the interobserver variations (P_EVAL). Plans from each group were stratified by observer and by number of catheters (12 or 16) and then compared using a one-way Kruskal-Wallis H test with post hoc Mann-Whitney U tests reserved for significant variations (α = 0.05).

RESULTS

Greater than 98.9% of catheter reconstruction variations were <3 mm. When stratified by observer, there was a significant decrease (p << 0.05) in planning target volume (PTV) V_100% and increases in the urethral D_max between the P_OBS plans propagated to the P_R catheter paths and dosimetry evaluated and P_R plans only. Stratification of plans by catheter number showed nonclinically significant decreases in PTV V_100%, and D_90% and increases in urethral D_max for the 12-catheter plans.

CONCLUSIONS

Limiting interobserver variability, and its effects on prostate HDR brachytherapy plan quality, is critical to achieving good dosimetric outcomes; small variations in catheter reconstruction may translate to inadequate PTV coverage, excessive urethral dose, or both.

Focal MRI-Guided Salvage High-Dose-Rate Brachytherapy in Patients With Radiorecurrent Prostate Cancer

Introduction:

Whole-gland salvage treatment of radiorecurrent prostate cancer has a high rate of severe toxicity. The standard of care in case of a biochemical recurrence is androgen deprivation treatment, which is associated with morbidity and negative effects on quality of life. A salvage treatment with acceptable toxicity might postpone the start of androgen deprivation treatment, might have a positive influence on the patients’ quality of life, and might even be curative. Here, toxicity and biochemical outcome are described after magnetic resonance imaging–guided focal salvage high-dose-rate brachytherapy in patients with radiorecurrent prostate cancer.

Materials and Methods:

Seventeen patients with pathologically proven locally recurrent prostate cancer were treated with focal high-dose-rate brachytherapy in a single 19-Gy fraction using magnetic resonance imaging for treatment guidance. Primary radiotherapy consisted of external beam radiotherapy or low-dose-rate brachytherapy. Tumors were delineated with Ga-68–prostate-specific membrane antigen or F18-choline positron emission tomography in combination with multiparametric magnetic resonance imaging. All patients had a prostate-specific antigen level of less than 10 ng/mL at the time of recurrence and a prostate-specific antigen doubling time of ≥12 months. Toxicity was measured by using the Common Terminology Criteria for Adverse Events version 4.

Results:

Eight of 17 patients had follow-up interval of at least 1 year. At a median follow-up interval of 10 months (range 3-40 months), 1 patient experienced a biochemical recurrence according to the Phoenix criteria, and prostate-specific membrane antigen testing revealed that this was due to a distant nodal metastasis. One patient had a grade 3 urethral stricture at 2 years after treatment.

Conclusion:

Focal salvage high-dose-rate brachytherapy in patients with radiorecurrent prostate cancer showed grade 3 toxicity in 1 of 17 patients and a distant nodal metastasis in another patient. Whether this treatment option leads to cure in a subset of patients or whether it can successfully postpone androgen deprivation treatment needs further investigation.

Impact of five-tiered Gleason grade groups on prognostic prediction in clinical stage T3 prostate cancer undergoing high-dose-rate brachytherapy

BACKGROUND

We evaluated a five-tiered Gleason grade groups arising from the 2014 International Society of Urological Pathology consensus conference on prognostic prediction in clinical stage T3a (extracapsular invasion) and T3b (seminal vesicle involvement) prostate cancer undergoing high-dose-rate brachytherapy (HDR-BT).

METHODS

From November 2003 to December 2012, 283 patients with stage T3 prostate cancer received HDR-BT and external beam radiation therapy (EBRT) with long-term androgen deprivation therapy (ADT). Of these, 203 (72%) and 80 (28%) patients had stage T3a and T3b disease, respectively. The mean dose to 90% of the planning target volume was 7.5 Gy/fraction of HDR-BT. After five fractions, EBRT with 10 fractions of 3 Gy was administered. All patients first underwent ≥6 months of neoadjuvant ADT, and adjuvant ADT continued for 36 months. Median follow-up was 74 months from the start of radiotherapy.

RESULTS

The 10-year biochemical recurrence (BCR) -free rate for stage T3a and T3b disease was 79% and 64%, respectively (P = 0.0083). The 10-year cancer-specific survival (CSS) rate for stage T3a and T3b was 96% and 91%, respectively (P = 0.0305). Although grade groups ≥4 were independent predictors for BCR in cT3a patients (P = 0.0270), they failed to significantly predict prostate cancer-specific mortality (PCSM) among cT3a patients. Among cT3b patients, grade group 5 was a significant predictor of both BCR (P = 0.0017) and PCSM (P = 0.0233). Among stage T3a patients, no significant difference existed in 10-year CSS between grade groups 5 and 4 (94% vs 97%, P = 0.3960). In contrast, grade group 5 had a significantly worse outcome in 10-year CSS than grade group 4 among stage T3b patients (74% vs 100%, P = 0.0350).

CONCLUSIONS

Stage T3a patients with grade groups 4/5 and stage T3b with grade group 4 had fairly low PCSM risk. Approximately one of four patients among stage T3b patients with grade group 5 showed PCSM after combined HDR-BT and EBRT with long-term ADT. Stage T3b patients with grade group 5 may have a greater risk for PCSM.

Fractionated high-dose-rate brachytherapy as monotherapy in prostate cancer: Does implant displacement and its correction influence acute and late toxicity?

PURPOSE

In fractionated high-dose-rate brachytherapy (HDR-BT) for prostate cancer (PCa) with one implant for several fractions, dose delivery relies on reproducibility of catheter positions. However, caudal displacement of implanted catheters does occur between fractions and needs to be corrected. Our protocol prescribes correction of displacements > 3 mm. We investigated whether displacement and its corrections influence acute and late toxicity incidences.

METHODS AND MATERIALS

We analyzed 162 PCa patients treated with HDR-BT monotherapy between 2007 and 2013. The implant remained in situ between the 4 fractions. Catheter displacement was assessed before each fraction using lateral X-ray images and corrected if needed. Genitourinary (GU) and gastrointestinal (GI) acute and late toxicities were assessed using clinical record forms and patient self-assessment questionnaires.

RESULTS

Implant displacement corrections (DC) were needed in 71 patients (43.8%) whereas no DCs were needed in 91 patients (56.2%). No statistically significant differences were seen in acute and late grade ≥ 2 GU and GI toxicity incidences between DC and no DC groups. The maximum displacement nor the number of corrections had any influence on toxicity.

CONCLUSIONS

The occurrence and subsequent correction of implant displacements exceeding 3 mm during fractionated HDR-BT monotherapy for PCa did not lead to increased incidences of acute or late GU and GI toxicity. This indicates that our clinical protocol to correct displacements > 3 mm results in safe treatment regarding organ at risk toxicity.