The anatomical and pathological characteristics of irradiated prostate cancers may influence the oncological efficacy of salvage ablative therapies

Topography of Prostate Cancer Recurrence: A Single-centre Analysis of Salvage Radical Prostatectomy Specimens and Implications for Focal Salvage Treatments

Background

Most prostate cancer (PCa) recurrences after nonsurgical first-line treatment are managed with androgen deprivation therapy (ADT). When local treatment is indicated, salvage focal treatment (FT) may achieve outcomes similar to those after salvage radical prostatectomy (sRP), with lower morbidity. However, descriptions of the topography of PCa recurrence are scarce.

Objective

To describe the characteristics and topography of recurrent PCa at sRP.

Design setting and participants

We performed a review of the final pathology for consecutive men undergoing sRP at a single centre between 2007 and 2021.

Outcome measurements and statistical analysis

Clinical and pathological outcomes and recurrence localisation (standardised map) were recorded. Suitability for salvage FT was evaluated using criteria defined a priori.

Results and limitations

We included 41 men who underwent sRP after whole-gland treatment (82.9% primary radiotherapy). Of these, 68.3% had grade group ≥3 and 46.3% had pT3 disease, including nine men (22%) with seminal vesicle involvement >1 cm. The pN+ rate was 29.3%. Surgical margins were positive in 39% (mostly at the apex, 21.9%). PCa was located at <3 mm from the apex in 68% of cases. The segment most frequently involved was the mid-gland (93%). The median prostate and index lesion (IL) volume was 31.4 cm³ (interquartile range [IQR] 23-37) and 2 cm³ (IQR 0.5-6), respectively. A solitary IL was present in 63.4% of cases, while 7.3% had whole-gland PCa involvement. Overall, 56% of the men (n = 23) were deemed suitable for salvage FT (although seven had pN+ disease). The sample size, single-centre retrospective design, and unavailability of magnetic resonance imaging data are the main limitations.

Conclusions

According to sRP pathology, radiorecurrent PCa is an aggressive disease, frequently showing extraprostatic extension, positive margins, and apical involvement. The majority of cases still harbour a solitary index lesion and a consistent proportion may be suitable for a gland-preserving strategy.

Patient summary

In this report we looked at the location of prostate cancer recurrence within the prostate gland after radiotherapy or ablation, in which energy (such as heat, cold, or laser energy) is used to kill cells. We found that although these recurrences are often high-grade locally advanced disease, around half of cases might be suitable for a gland-preserving salvage treatment.

Comparison between MRI and choline-PET trans-perineal target biopsies and saturation biopsies for detection and topography of intra-prostatic recurrence after primary radiation therapy for prostate cancer

INTRODUCTION

Biochemical recurrence of prostate cancer after radiation therapy occurs in 5 to 50% of cases depending on the radiation technique used. The diagnosis of recurrence of prostate adenocarcinoma must be made accurately. The aim of this study was to compare transperineal saturation and target biopsies to index lesion (IL) as defined on MRI and 18FCholine PET-CT (PETc) for detection of intra-prostatic recurrence after primary radiation therapy for prostate cancer.

MATERIALS AND METHODS

Thirty-eight patients with an history of prostate radiation for prostate cancer and biochemical recurrence were retrospectively included between March 2013 and June 2017. All patients had PETc and multiparametric MRI (MRI) defining IL. All patients had transperineal saturation biopsies and target biopsies the IL.

RESULTS

Among 38 patients with biochemical recurrence, 33 (87%) had biopsy proven recurrence in the prostate. The sensitivity and specificity of MRI were 32% (SD:19%) and 91% respectively (SD:7%). The sensitivity and specificity of PETc were 33% (SD:22%) and 78% respectively (SD:12%). Saturation trans-perineal and target biopsies allowed detection of disease recurrence in 79% and 84% of patients, respectively.

CONCLUSION

In case of positive imaging, both trans-perineal prostate saturation and target biopsies offer good performance to confirm intraprostatic recurrence. However, MRI and PETc low sensitivity to detect all sites of local recurrence of prostate cancer after radiation still justify the completion of systematic saturation biopsies.

LEVEL OF EVIDENCE

3.

Dosimetry of local failure with single dose 19 Gy high-dose-rate brachytherapy for prostate cancer

PURPOSE/OBJECTIVE

Long-term follow up of single dose high-dose rate brachytherapy (HDR BT) for localised prostate cancer has revealed higher than expected rates of biochemical and local failure. This study aimed (i) to investigate the pattern of relapse within the prostate with reference to the initial site of disease in those patients; and (ii) to examine if there were any relationships between the HDR BT dosimetric parameters to these areas of recurrence.

MATERIALS/METHODS

A retrospective review of treatment records of patients who received 19 Gy single fraction of HDR BT was carried out. A matched pair analysis used one control for each biochemical recurrence case matched with pre-treatment Clinical target volume (CTV) size, Gleason score, T stage, risk category and presence of an identifiable dominant intraprostatic nodule (DIL) for each biochemical recurrence case identified. For all datasets, the pre HDR BT DILs were delineated on the diagnostic pre-treatment T2-weighted MRI and planning CT images. For patients with local recurrence post HDR BT, the recurrent nodules were contoured on the diagnostic T2-weighted MRI and choline PET which were registered to the original HDR BT planning CT. Dosimetric parameters of CTV, planning target volume (PTV), DIL and organs at risk (OARs) were evaluated. Wilcoxon signed-rank test was performed to investigate if there were any significant differences in dosimetric parameters between cases and controls. Cox regression analysis was performed to explore if there were any clinical and dosimetric parameters predicting for biochemical progression free survival (bPFS), local recurrence free survival (LR-PFS) and DIL recurrence free survival (DIL-PFS).

RESULTS

Between 2013 and 2018, 180 patients received 19 Gy HDR-BT monotherapy. With a median follow up of 36 months, 19 (10.6%) patients developed biochemical recurrence. Of the 19 patients with biochemical failure, 13 had a local recurrence, including 7 who occurred at the site of DIL. Thirty-eight intermediate/high risk patients were included in the matched pair analysis. No statistically significant differences were found in all CTV, PTV, DIL and OAR dosimetric parameters between cases and controls (p > 0.05). For the Cox regression analysis, none of the covariates investigated were found to be statistically significant factors to predict for bPFS, LC-PFS and DIL-PFS.

CONCLUSION

No associations between biochemical recurrences and HDR BT dosimetry were identified in our cohort of patients receiving 19 Gy single fraction HDR BT. A large proportion of recurrences occurred at the site of original disease. HDR BT for intermediate/high risk prostate cancer should be undertaken using a minimum of two fractions.

Percutaneous MR-guided whole-gland prostate cancer cryoablation: safety considerations and oncologic results in 30 consecutive patients

OBJECTIVE

To assess the safety and oncological efficacy of percutaneous MR-guided whole-gland prostate cancer (PCa) cryoablation (CA).

METHODS AND MATERIALS

Between July 2009 and January 2018, 30 patients (mean age 72.9 ± 5.13 years) with histologically proven, organ-confined (≤ T2cN0M0), predominantly low/intermediate-risk PCa (median Gleason score 7; mean prostate specific antigen 6.05 ± 3.74 ng ml^-1 ) underwent MR-guided whole-gland CA. Patients were selected on the basis of prior pelvic radiotherapy (n = 16; 12 for previous PCa), or contra indication/refusal of surgery or radiotherapy. Complications, local progression-free survival (LPFS) and overall survival (OS) were retrospectively investigated.

RESULTS

Eighteen [60%] patients reported procedure-related complications: 5/18 [28%] needed surgical/interventional treatments and 13 [72%] conservative or pharmacological treatment. Eleven [73%] complications were noted in the first 15 patients and 7 [47%] in the last 15 patients (p = 0.26). Mean nadir prostate specific antigen was 0.24 ± 1.5 ng ml^-1 (mean follow-up 3.8 years; range: 2 - 2915 days). Seven [23%] patients developed histologically proven local progression (mean time to recurrence 775 days, range: 172 - 2014). Mean clinical follow-up was 3.8 years (range 1-2915 days). LPFS was 92.0, 75.7 and 69.4 % at 1-, 3- and 5 year follow-up, respectively. For patients in salvage treatment, LPFS was 100%, 75%, and 75% at 1-, 3- and 5 year follow-up. OS was 100%, 94.4 and 88.5 % at 1-, 3- and 5 year follow-up respectively, with no patients dying from PCa.

CONCLUSION

Whole-gland PCa CA offers good oncological efficacy, particularly in post-radiotherapy cases. Although the complication rate is significant, the majority is minor and is managed with conservative or pharmacologic management.

ADVANCES IN KNOWLEDGE

MRI-guided whole-gland prostate cancer cryoablation offers good oncological efficacy, particularly in post-radiotherapy cases with a contained complication rate.

Topography of Prostate Cancer Recurrence After Radiation Therapy: A Detailed Mapping Study of Salvage Radical Prostatectomy Specimens

In men who do not respond to initial radiation therapy, accurate knowledge of the site of cancer recurrence or persistence is necessary to understand treatment failure. We evaluated the pathologic characteristics of recurrent/persistent prostate cancer with tumor maps from the whole-mount slides of salvage radical prostatectomies performed between 2000 and 2014. Of 216 consecutive patients, detailed tumor maps were available for 77. Sixty-nine patients (90%) were found to have tumor in the apex, of which 46% occurred in the most apical 3mm. Fifty-three patients (69%) had tumors at a distance of ≤5mm from the urethra. Five patients had tumor directly involving the urethra, all of whom had urethral invasion at the apex. Seminal vesicle involvement was seen in 32 patients (42%), two of whom had tumor only in the seminal vesicles. Sixty-two patients (81%) had tumors in the distal apex, periurethral area, or seminal vesicles, that is, areas that are not routinely biopsied. Targeting these areas could improve the accuracy of biopsy when cancer recurrence is suspected.

PATIENT SUMMARY

When recurrence is suspected, clinicians should include biopsy of the distal apex, areas surrounding the urethra, and seminal vesicles. This information will help tailor successful salvage treatments.

A Monte Carlo study of I-125 prostate brachytherapy with gold nanoparticles: dose enhancement with simultaneous rectal dose sparing via radiation shielding

We investigate via Monte Carlo simulations a new ¹²⁵I brachytherapy treatment technique for high-risk prostate cancer patients via injection of Au nanoparticle (AuNP) directly into the prostate. The purpose of using the nanoparticles is to increase the therapeutic index via two synergistic effects: enhanced energy deposition within the prostate and simultaneous shielding of organs at risk from radiation escaping from the prostate. Both uniform and non-uniform concentrations of AuNP are studied. The latter are modeled considering the possibility of AuNP diffusion after the injection using brachy needles. We study two extreme cases of coaxial AuNP concentrations: centered on brachy needles and centered half-way between them. Assuming uniform distribution of 30 mg g^-1 of AuNP within the prostate, we obtain a dose enhancement larger than a factor of 2 to the prostate. Non-uniform concentration of AuNP ranging from 10 mg g^-1 and 66 mg g^-1 were studied. The higher the concentration in a given region of the prostate the greater is the enhancement therein. We obtain the highest dose enhancement when the brachytherapy needles are coincident with AuNP injection needles but, at the same time, the regions in the tail are colder (average dose ratio of 0.7). The best enhancement uniformity is obtained with the seeds in the tail of the AuNP distribution. In both uniform and non-uniform cases the urethra and rectum receive less than 1/3 dose compared to an analog treatment without AuNP. Remarkably, employing AuNP not only significantly increases dose to the target but also decreases dose to the neighboring rectum and even urethra, which is embedded within the prostate. These are mutually interdependent effects as more enhancement leads to more shielding and vice-versa. Caution must be paid since cold spot or hot spots may be created if the AuNP concentration versus seed position is not properly distributed respect to the seed locations.

Interstitial high-dose-rate brachytherapy as salvage treatment for locally recurrent prostate cancer after definitive radiation therapy: Toxicity and 5-year outcome

PURPOSE

We report our results with interstitial high-dose-rate brachytherapy (HDR-BT) as a salvage therapy option after external beam therapy with or without BT. Emphasis was put on toxicity and 5-year outcome.

METHODS AND MATERIALS

From 2003 to 2011, 29 patients with local failure after previous radiotherapy for prostate cancer were treated with salvage interstitial HDR-BT. The diagnosis of local recurrence was made on the basis of choline positron emission tomography. Salvage HDR-BT was given in three fractions with a single dose of 10 Gy per fraction and weekly. The target volume covered the peripheral zone of the prostate and the positron emission tomography-positive area. Acute and late toxicities were documented according to common terminology criteria for adverse events (CTCAE v 4.0).

RESULTS

Twenty-two patients with minimum followup of 60 months were analyzed. The 5-year overall survival was 95.5% with a disease-specific survival of 100%. The 5-year biochemical control was 45%. Late grade 2 gastrointestinal toxicities were observed in two patients (9%). No grade 3 or higher gastrointestinal late toxicities were observed. Urinary incontinence found in 2 patients (9%) and grade 2 obstruction of urinary tract occurred in one patient (4%).

CONCLUSIONS

Interstitial HDR-BT was feasible and effective in the treatment of locally recurrent prostate cancer after definitive radiotherapy. The long-term toxicity was low and acceptable.

Single fraction multimodal image guided focal salvage high-dose-rate brachytherapy for recurrent prostate cancer

PURPOSE

We present a novel method for treatment of locally recurrent prostate cancer (PCa) following radiation therapy: focal, multimodal image guided high-dose-rate (HDR) brachytherapy.

MATERIAL AND METHODS

We treated two patients with recurrent PCa after primary (#1) or adjuvant (#2) external beam radiation therapy. Multiparametric magnetic resonance imaging (mpMRI), choline, positron emission tomography combined with computed tomography (PET/CT), or prostate-specific membrane antigen (PSMA)-PET combined with CT identified a single intraprostatic lesion. Positron emission tomography or magnetic resonance imaging - transrectal ultrasound (MRI-TRUS) fusion guided transperineal biopsy confirmed PCa within each target lesion. We defined a PET and mpMRI based gross tumor volume (GTV). A 5 mm isotropic margin was applied additionally to each lesion to generate a planning target volume (PTV), which accounts for technical fusion inaccuracies. A D90 of 18 Gy was intended in one fraction to each PTV using ultrasound guided HDR brachytherapy.

RESULTS

Six month follow-up showed adequate prostate specific antygen (PSA) decline in both patients (ΔPSA 83% in patient 1 and ΔPSA 59.3% in patient 2). Follow-up 3-tesla MRI revealed regressive disease in both patients and PSMA-PET/CT showed no evidence of active disease in patient #1. No acute or late toxicities occurred.

CONCLUSIONS

Single fraction, focal, multimodal image guided salvage HDR brachytherapy for recurrent prostate cancer is a feasible therapy for selected patients with single lesions. This approach has to be evaluated in larger clinical trials.

Focal salvage therapy for local prostate cancer recurrences after primary radiotherapy: a comprehensive review

Background/Aim

Patients with locally recurrent prostate cancer after primary radiotherapy can be eligible for salvage treatment. Whole-gland salvage techniques carry a high risk of toxicity. A focal salvage approach might reduce the risk of adverse events while maintaining cancer control in carefully selected patients. The aim of this review was to evaluate current literature to assess whether focal salvage leads to a comparable or favourable recurrence rate and less toxicity compared to whole-gland salvage.

Methods

A literature search was performed using PubMed, Embase and the Cochrane Library. A total of 3015 articles were screened and assessed for quality. Eight papers [on focal cryoablation (n = 3), brachytherapy (n = 3) and high-intensity focused ultrasound (n = 2)] were used to report outcomes.

Results

One-, 2-, 3- and 5-year biochemical disease-free survival (BDFS) ranges for focal salvage are, respectively, 69–100, 49–100, 50–91 and 46.5–54.5 %. Severe genitourinary, gastrointestinal and sexual function toxicity rates are 0–33.3 %. One study directly compares focal to whole-gland salvage cryotherapy, showing 5-year BDFS of, respectively, 54.4 and 86.5 % with lower toxicity rates for focal salvage patients.

Conclusion

Provisional data suggest that BDFS rates of focal salvage are in line with those of whole-gland approaches. There is evidence that focal salvage could decrease severe toxicity and preserve erectile function.

Electronic supplementary material

The online version of this article (doi:10.1007/s00345-016-1811-9) contains supplementary material, which is available to authorized users.

Focal salvage iodine-125 brachytherapy for prostate cancer recurrences after primary radiotherapy: a retrospective study regarding toxicity, biochemical outcome and quality of life

PURPOSE

Whole-gland salvage for recurrent prostate cancer (PCa) shows high failure and toxicity rates. Early and adequate localization of recurrences enables focal salvage, thereby potentially improving functional outcomes, while maintaining cancer control.

MATERIALS AND METHODS

Retrospective analysis yielded 20 focal salvage I125 brachytherapy patients for locally recurrent PCa after primary radiotherapy. Tumor was defined by multiparametric MRI and correspondence with transrectal biopsies. Dose data were obtained intra-operatively. The tumor was prescribed ⩾144 Gy. Toxicity was scored by the Common Terminology Criteria for Adverse Events version 4 (CTCAE-4). Biochemical failure (BF) was defined using the Phoenix criteria (PSA-nadir + 2.0 ng/ml). Quality of life (QoL) was measured by SF-36 Health Survey and European Organization of Research and Treatment of Cancer (EORTC) C30+3 and PR25 questionnaires.

RESULTS

With a median follow-up of 36 months (range 10-45), six patients experienced BF, of which three had no initial response. Grade 3 genitourinary (GU) toxicity occurred in one patient (a urethral stricture). The five previously potent patients retained erectile function. QoL remained decreased with regard to urinary symptoms.

CONCLUSION

Focal salvage I125 brachytherapy showed one grade 3 GU toxicity in the 20 treated patients. Biochemical response and QoL were acceptable.

Salvage focal and salvage total cryoablation for locally recurrent prostate cancer after primary radiation therapy

OBJECTIVES

To present the oncological and functional outcomes of salvage focal (SFC) and salvage total (STC) cryoablation for recurrent prostate cancer (PCa) after failed primary radiotherapy.

PATIENTS AND METHODS

From March 2003 to August 2010, 50 men with biopsy-proven unilateral (n = 25) or bilateral (n = 25) radio-recurrent PCa underwent SFC or STC, respectively. Patients were assessed after treatment by prostate-specific antigen (PSA) testing, transrectal ultrasonography, biopsy and questionnaires. Biochemical failure (BF) was defined using the Phoenix criteria (PSA nadir + 2 mg/mL). Data were prospectively collected and retrospectively analysed.

RESULTS

The median pre-cryoablation PSA level and Gleason score were, respectively, 2.8 ng/mL and 7 for SFC, and 3.9 ng/mL and 7 for STC. The median follow-up was 31 and 53 months (P = 0.004) for SFC and STC, respectively. Oncological outcomes were as follows: no patient died; one patient who underwent STC developed bone metastases; eight patients who underwent SFC and three who underwent STC had BF and the 5-year BF-free survival rates were 54 and 86%, respectively. In those patients without BF, the mean PSA decreased by 86% for SFC and 90% for STC within the first year and remained stable. Functional outcomes were as follows: new onset urinary incontinence occurred in three (13%) patients in the STC group, whereas no patient in the SFC group developed incontinence (P = 0.10); Two of seven patients in the SFC group retained postoperative potency, but none of the four potent patients in the STC group recovered potency postoperatively (P = 0.48); one (4%) patient in the STC group developed a recto-urethral fistula, but none occurred in the SFC group (P = 0.48).

CONCLUSIONS

SFC and STC are feasible and safe with acceptable mid-term oncological outcomes. For carefully selected patients, SFC is an option that could be associated with lower treatment-related morbidity compared with STC. Although longer follow-up and more patient numbers are needed, our initial oncological and functional outcomes of SFC and STC are encouraging.

The dilemma of a rising prostate-specific antigen level after local therapy: what are our options?

Prostate cancer is the most common solid tumor diagnosed in men in the United States and Western Europe. Primary treatment with radiation or surgery is largely successful at controlling localized disease. However, a significant number (up to one third of men) may develop biochemical recurrence (BR), defined as a rise in serum prostate-specific antigen (PSA) level. A general presumption is that BR will lead to overt progression in patients over subsequent years. There are a number of factors that a physician must consider when counseling and recommending treatment to a patient with a rising PSA. These include the following (1) various PSA-based definitions of BR; (2) source of PSA (ie, local or distant disease, residual benign prostate); (3) available modalities to treat the disease with the least morbidity; and (4) timing of therapy. In this article we review the current and future factors that clinicians should consider in the diagnosis and treatment of recurrent prostate cancer.

Focal salvage therapy for localized prostate cancer recurrence after external beam radiotherapy: a pilot study

BACKGROUND

The objective of this study was to evaluate the safety, feasibility, side-effect profile, and proof of concept for focal salvage therapy using high-intensity focused ultrasound (HIFU).

METHODS

A registry-based analysis was conducted between 2004 and 2009 of 430 patients who underwent HIFU. Thirty-nine patients received focal salvage therapy for localized recurrence after external beam radiotherapy. Multiparametric magnetic resonance imaging studies combined with transperineal template prostate mapping biopsies or transrectal biopsies were used to localize disease. Validated questionnaires were used to assess functional outcomes. Biochemical failure was defined by using both Phoenix criteria (prostate-specific antigen [PSA] nadir plus 2 ng/mL) and Stuttgart criteria (PSA nadir plus 1.2 ng/mL).

RESULTS

The mean pre-HIFU PSA level was 4.6 ng/mL. The median follow-up was 17 months (interquartile range, 10-29 months). International Index of Erectile Function-5 scores decreased from a median ± standard deviation (SD) of 18 ± 16 to 13 ± 21 at 6 months, demonstrating worsening function. Scores on the University of California Los Angeles-Expanded Prostate Cancer Index Composite Urinary domain indicate that pad-free, leak-free continence status was 64%, and the pad-free rate was 87.2% at last follow-up. One rectourethral fistula occurred and spontaneously resolved with urinary and bowel diversion. The actuarial progression-free survival rate (including PSA nonresponders) was 69% at 1 year and 49% at 2 years according to Phoenix criteria. Excluding PSA nonresponders, these rates were 74% and 58%, respectively (Phoenix criteria).

CONCLUSIONS

The results from this study indicated that focal salvage therapy is a potential strategy for localized recurrence after radiotherapy that may reduce the harms resulting from whole-gland salvage therapies.

Salvage cryotherapy for radiation-recurrent prostate cancer: outcomes and complications

Potentially curative salvage options for radio-recurrent prostate cancer include prostatectomy, brachytherapy, high-intensity focused ultrasound, and cryotherapy. Salvage cryoablation technology, surgical technique, oncologic outcomes, and complication rates have improved dramatically over the past few decades, shifting this treatment modality from investigational status to an established therapeutic option. In this review, we focus on the most up-to-date oncologic and functional outcomes, as well as complications of salvage cryotherapy for radiation-recurrent prostate cancer.

18F-fluorocholine PET-guided target volume delineation techniques for partial prostate re-irradiation in local recurrent prostate cancer

BACKGROUND AND PURPOSE

We evaluate the contribution of (18)F-choline PET/CT in the delineation of gross tumour volume (GTV) in local recurrent prostate cancer after initial irradiation using various PET image segmentation techniques.

MATERIALS AND METHODS

Seventeen patients with local-only recurrent prostate cancer (median=5.7 years) after initial irradiation were included in the study. Rebiopsies were performed in 10 patients that confirmed the local recurrence. Following injection of 300 MBq of (18)F-fluorocholine, dynamic PET frames (3 min each) were reconstructed from the list-mode acquisition. Five PET image segmentation techniques were used to delineate the (18)F-choline-based GTVs. These included manual delineation of contours (GTV(man)) by two teams consisting of a radiation oncologist and a nuclear medicine physician each, a fixed threshold of 40% and 50% of the maximum signal intensity (GTV(40%) and GTV(50%)), signal-to-background ratio-based adaptive thresholding (GTV(SBR)), and a region growing (GTV(RG)) algorithm. Geographic mismatches between the GTVs were also assessed using overlap analysis.

RESULTS

Inter-observer variability for manual delineation of GTVs was high but not statistically significant (p=0.459). In addition, the volumes and shapes of GTVs delineated using semi-automated techniques were significantly higher than those of GTVs defined manually.

CONCLUSIONS

Semi-automated segmentation techniques for (18)F-choline PET-guided GTV delineation resulted in substantially higher GTVs compared to manual delineation and might replace the latter for determination of recurrent prostate cancer for partial prostate re-irradiation. The selection of the most appropriate segmentation algorithm still needs to be determined.

RapidArc, intensity modulated photon and proton techniques for recurrent prostate cancer in previously irradiated patients: a treatment planning comparison study

Background

A study was performed comparing volumetric modulated arcs (RA) and intensity modulation (with photons, IMRT, or protons, IMPT) radiation therapy (RT) for patients with recurrent prostate cancer after RT.

Methods

Plans for RA, IMRT and IMPT were optimized for 7 patients. Prescribed dose was 56 Gy in 14 fractions. The recurrent gross tumor volume (GTV) was defined on ¹⁸F-fluorocholine PET/CT scans. Plans aimed to cover at least 95% of the planning target volume with a dose > 50.4 Gy. A maximum dose (D_Max) of 61.6 Gy was allowed to 5% of the GTV. For the urethra, D_Max was constrained to 37 Gy. Rectal D_Median was < 17 Gy. Results were analyzed using Dose-Volume Histogram and conformity index (CI₉₀) parameters.

Results

Tumor coverage (GTV and PTV) was improved with RA (V_95% 92.6 ± 7.9 and 83.7 ± 3.3%), when compared to IMRT (V_95% 88.6 ± 10.8 and 77.2 ± 2.2%). The corresponding values for IMPT were intermediate for the GTV (V_95% 88.9 ± 10.5%) and better for the PTV (V_95%85.6 ± 5.0%). The percentages of rectal and urethral volumes receiving intermediate doses (35 Gy) were significantly decreased with RA (5.1 ± 3.0 and 38.0 ± 25.3%) and IMPT (3.9 ± 2.7 and 25.1 ± 21.1%), when compared to IMRT (9.8 ± 5.3 and 60.7 ± 41.7%). CI₉₀ was 1.3 ± 0.1 for photons and 1.6 ± 0.2 for protons. Integral Dose was 1.1 ± 0.5 Gy*cm³ *10⁵ for IMPT and about a factor three higher for all photon's techniques.

Conclusion

RA and IMPT showed improvements in conformal avoidance relative to fixed beam IMRT for 7 patients with recurrent prostate cancer. IMPT showed further sparing of organs at risk.

Locally ablative therapies for primary radiation failures: a review and critical assessment of the efficacy

A significant number of men with prostate cancer will experience biochemical failure following treatment with primary radiation therapy. For patients with biopsy-proven recurrent cancer confined to the prostate, local salvage therapy may be a potentially curative treatment option. Most men, however, do not undergo local salvage therapy owing to difficulties in diagnosis as well as concerns over treatment-related complications in the salvage setting. Recently, improvements in technique and technology have substantially reduced the morbidity associated with locally ablative therapies, resulting in an increased interest in the use of minimally invasive therapies such as brachytherapy, cryotherapy, and high-intensity focused ultrasound in the salvage setting. Although these treatments are well tolerated, concerns remain over incomplete and inadequate treatment with locally ablative therapies. Future studies are required to appropriately select candidates for salvage ablative therapies and to determine the long-term oncologic efficacy of these treatments.