Salvage CyberKnife-Based Reirradiation of Patients With Recurrent Prostate Cancer: The Single-Center Experience

Re-irradiation to the prostate using stereotactic body radiotherapy (SBRT) after initial definitive radiotherapy - A systematic review and meta-analysis of recent trials

Background

There is increasing data on re-irradiation to the prostate using stereotactic body radiotherapy (SBRT) after definitive radiotherapy for prostate cancer, with increasing evidence on prostate re-irradiation using a C-arm LINAC or an MR LINAC in recent years. We therefore conducted this systematic review and meta-analysis on prostate re-irradiation including studies published from 2020 to 2023, to serve as an update on existing meta-analysis.

Methods

We searched the PubMed and Embase databases in October 2023 with queries including combinations of "repeat", "radiotherapy", "prostate", "re-irradiation", "reirradiation", "re treatment", "SBRT", "retreatment". Publication date was set to be from 2020 to 2023. There was no limitation regarding language. We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. After data extraction, heterogeneity testing was done by calculating the I2. A random effects model with a restricted maximum likelihood estimator was used to estimate the combined effect. Funnel plot asymmetry was assessed visually and using Egger's test to estimate the presence of publication and/or small study bias.

Results

14 publications were included in the systematic review. The rates of acute ≥ grade 2 (G2) genitourinary (GU) and gastrointestinal (GI) toxicities reported in the included studies ranged from 0.0-30.0 % and 0.0-25.0 % respectively. For late ≥ G2 GU and GI toxicity, the ranges are 4.0-51.8 % and 0.0-25.0 %. The pooled rate of acute GU and GI toxicity ≥ G2 were 13 % (95 % CI: 7-18 %) and 2 % (95 % CI: 0-4 %). For late GU and GI toxicity ≥ G2 the pooled rates were 25 % (95 % CI: 14-35 %) and 5 % (95 % CI: 1-9 %). The pooled 2-year biochemical recurrence-free survival was 72 % (95 % CI: 64-92 %).

Conclusions

SBRT in the re-irradiation of radiorecurrent prostate cancer is safe and effective. Further prospective data are warranted.

Stereotactic body radiotherapy (SBRT) re-irradiation for local failures following radical prostatectomy and post-operative radiotherapy

PURPOSE

Local recurrences after radical prostatectomy (RP) and postoperative radiotherapy (RT) are challenging for salvage treatment. Retrospective analysis of own experiences with salvage re-irradiation was performed.

METHODS

The study included all consecutive patients treated with salvage stereotactic body radiotherapy (sSBRT) for prostate bed recurrence following RP and postoperative RT at a single tertiary center between 2014 and 2021. Treatment toxicity defined as the occurrence of CTCAE grade ≥ 2 genito-urinary (GU) or gastro-intestinal (GI) adverse events (AEs) was assessed. A PSA response, biochemical control (BC) and overall survival (OS) were also evaluated.

RESULTS

The study group included 32 patients with a median age of 68 years and a median follow-up of 41 months, treated with CyberKnife (53%) or Linac (47%) sSBRT. Total dose of 33.75-36.25 Gy in five fractions (72%) was applied in the majority of them. Approximately 19% patients reported grade ≥ 2 GU AEs both at baseline and at three months, and grade ≥ 2 GI toxicity increased from 0% at baseline to 6% at three months after sSBRT. There was some clinically relevant increase in late toxicity with 31% patients reporting late ≥ 2 GU, and 12.5% late ≥ 2 GI AEs. Two grade 3 AEs were recorded: recto-urinary fistulas. The majority of patients showed a PSA response (91% at one year post-sSBRT). The 3‑year BC was 40% and 3‑year OS was 87%.

CONCLUSIONS

Manageable toxicity profile and satisfactory biochemical response suggest that SBRT in patients with local recurrence following RP and postoperative RT might be a salvage option for selected patients.

Achievable Dosimetric Constraints in Stereotactic Reirradiation for Recurrent Prostate Cancer

PURPOSE

Stereotactic body radiation therapy has been proposed as a salvage treatment for recurrent prostate cancer after irradiation. One crucial issue is choosing appropriate dose-volume constraints (DVCs) during planning. The objectives of this study were to (1) quantify the proportion of patients respecting the DVCs according to the Urogenital Tumor Study Group GETUG-31 trial, testing 36 Gy in six fractions, (2) explain geometrically why the DVCs could not be respected, and (3) propose the most suitable DVCs.

METHODS AND MATERIALS

This retrospective dosimetric analysis included 141 patients treated for recurrent prostate cancer with Cyberknife (Accuray), according to GETUG-31 DVCs: V95% ≥ 95% for the planning target volume (PTV), V12Gy < 20% and V27Gy < 2 cc for the rectum, and V12Gy < 15% and V27Gy < 5 cc for the bladder. The percentage of patients not respecting the DVCs was quantified. Correlations between the DVCs and anatomic structures were examined. New DVCs were proposed.

RESULTS

Only 19% of patients respected all DVCs, with a mean PTV of 18.5 cc (range, 3-48 cc), although the mean PTV was 40.5 cc (range, 3-174 cc) in the whole series. A total of 98% of the patients with a clinical target volume (CTV)/prostate ratio >0.5 could not respect the DVCs in the organs at risk. The target coverage and organ-at-risk sparing decreased significantly with increase in the values of PTV, CTV, CTV/prostate ratio, the overlapping volume between the PTV and bladder wall and between the PTV and rectal wall. Threshold values of PTV, >20 cc and 40 cc, allowed for the PTV and bladder DVCs, respectively. To improve DVC respect in case of large target volume, we proposed the following new DVCs: V12Gy < 25% and 25% and V27Gy < 2 cc and 5 cc for the rectum and bladder, respectively.

CONCLUSIONS

GETUG-31 DVCs are achievable only for small target volumes (CTV more than half of the prostate). For a larger target volume, new DVCs have been proposed.

PSMA PET-based stereotactic body radiotherapy for locally recurrent prostate cancer after definitive first-line therapy

BACKGROUND

Advances in prostate-specific membrane antigen (PSMA) PET-computed tomography (CT) and magnetic resonance imaging (MRI) allow the detection and localization of exclusively local prostate-cancer-recurrences after definitive first-line therapy. PSMA-based early detection of circumscribed local recurrences followed by hypofractionated high-precision stereotactic body radiotherapy (SBRT) might yield long-term disease control at moderate rates of adverse effects.

METHODS

Retrospective analysis of 35 patients treated for locally recurrent prostate cancer between November 2012 and December 2021 with PSMA PET- and MRI-based robotic SBRT.

RESULTS

Thirty-five patients treated with local prostate cancer recurrence post surgery, post surgery, and adjuvant/salvage radiotherapy (RT) and after definitive RT. All but one patients had fractionated SBRT in 3-5 fractions. Median progression-free survival (PFS) was 52.2 months for all patients and 52.2 months in the radical prostatectomy (RPE) group, 31.2 months in the RPE + RT group and not reached in the RT group. The most common event was increased urinary frequency grade 1-2. 54.3% of all patients had no acute and 79.4% no late toxicity during follow-up.

DISCUSSION

Our PFS of 52.2 months (RPE), 31.2 months (RPE + RT) and not reached (RT) compares favorably with published data. This method constitutes a valid alternative to morbidity-prone invasive approaches or palliative systemic therapy.

Linac-based stereotactic salvage reirradiation for intraprostatic prostate cancer recurrence: toxicity and outcomes

BACKGROUND

The rates of local failure after curative radiotherapy for prostate cancer (PC) remain high despite more accurate locoregional treatments available, with one third of patients experiencing biochemical failure and clinical relapse occurring in 30-47% of cases. Today, androgen deprivation therapy (ADT) is the treatment of choice in this setting, but with not negligible toxicity and low effects on local disease. Therefore, the treatment of intraprostatic PC recurrence represents a challenge for radiation oncologists. Prostate reirradiation (Re-I) might be a therapeutic possibility. We present our series of patients treated with salvage stereotactic Re‑I for intraprostatic recurrence of PC after radical radiotherapy, with the aim of evaluating feasibility and safety of linac-based prostate Re‑I.

MATERIALS AND METHODS

We retrospectively evaluated toxicities and outcomes of patients who underwent salvage reirradiation using volumetric modulated arc therapy (VMAT) for intraprostatic PC recurrence. Inclusion criteria were age ≥ 18 years, histologically proven diagnosis of PC, salvage Re‑I for intraprostatic recurrence after primary radiotherapy for PC with curative intent, concurrent/adjuvant ADT with stereotactic body radiation therapy (SBRT) allowed, performance status ECOG 0-2, restaging choline/PSMA-PET/TC and prostate MRI after biochemical recurrence, and signed informed consent.

RESULTS

From January 2019 to April 2022, 20 patients were recruited. Median follow-up was 26.7 months (range 7-50). After SBRT, no patients were lost at follow-up and all are still alive. One- and 2‑year progression free survival (PFS) was 100% and 81.5%, respectively, while 2‑year biochemical progression-free survival (bFFS) was 88.9%. Four patients (20%) experienced locoregional lymph node progression and were treated with a further course of SBRT. Prostate reirradiation allowed the ADT start to be postponed for 12-39 months. Re‑I was well tolerated by all patients and none discontinued the treatment. No cases of ≥ G3 genitourinary (GU) or gastrointestinal (GI) toxicity were reported. Seven (35%) and 2 (10%) patients experienced acute G1 and G2 GU toxicity, respectively. Late GU toxicity was recorded in 10 (50%) patients, including 8 (40%) G1 and 2 (10%) G2. ADT-related side effects were found in 7 patients (hot flashes and asthenia).

CONCLUSION

Linac-based SBRT is a safe technique for performing Re‑I for intraprostatic recurrence after primary curative radiotherapy for PC. Future prospective, randomized studies are desirable to better understand the effectiveness of reirradiation and the still open questions in this field.

Reirradiation of Locally Recurrent Prostate Cancer with Cyberknife® System or Volumetric Modulated Arc Therapy (VMAT) and IGRT-Clarity®: Outcomes, Toxicities and Dosimetric Evaluation

The management of prostate cancer recurrence following external beam radiotherapy is not defined yet. Stereotaxic body reirradiation therapy showed encouraging results for local and biochemical control. From April 2017 to December 2020, 29 patients with prostate cancer recurrence were collected, joining the retrospective studies CyPro (prot. 46/19 OSS) and CLARO (Prot. 19/20 OSS) trials. Patients received Cyberknife® treatment (17 pts) or alternatively VMAT (Volumetric Modulated Arc Technique) therapy by IGRT (Image-Guided Radiation Therapy)/Clarity® (12 pts). By comparing the reirradiation of two groups, urinary (GU), rectal (GI) toxicities, and biochemical control were investigated. Further, the two techniques were dosimetrically compared by rival plans. The VMAT-IGRT Clarity® treatments were replanned with an optimized template developed for prostate VMAT-SBRT in FFF mode keeping the same dose and fractionation scheduled for Cyberknife Group (30 Gy in 5 fx, at 80% isodose). In the CK group, 23% of patients experienced grade 2 acute GU, while 6% grade 2 acute GI. In the VMAT-Clarity® group, acute GU toxicity was recorded in 17%, while for 8% grade 2 late toxicity was recorded. The dosimetric analysis shows that the VMAT-FFF allows to deliver a biological equivalent dose to CK, with the advantage of reducing the likelihood of toxicities arising.

Stereotactic Re-irradiation in Recurrent Prostate Cancer after Previous Postoperative or Definitive Radiotherapy: Long-term Results after a Median Follow-up of 4 Years

AIMS

In 2018, we published early results from a cohort of patients treated with stereotactic body radiotherapy (SBRT) after previous radiotherapy with definitive or postoperative intent. We sought to provide extended follow-up of this cohort to confirm the safety and efficacy of this approach in a real-world scenario.

MATERIALS AND METHODS

Fifty patients affected by local relapse after previous definitive or postoperative radiotherapy were treated with SBRT. Treatment provided a total dose of 30 Gy in five fractions. Data about biochemical relapse-free survival (BRFS) and metastasis-free survival (MFS), together with adverse events, were analysed. Toxicity was reported according to Common Terminology Criteria for Adverse Events (CTCAE) score v.4.03.

RESULTS

After a median follow-up of 48.2 months, the median BRFS was 43 months. A Gleason score >7 and concomitant androgen deprivation therapy were shown to be predictors of the worst BRFS (hazard ratio 2.42, 95% confidence interval 1.09-5.41, P = 0.02; hazard ratio 2.83, 95% confidence interval 1.17-6.8, P = 0.02, respectively). The median MFS was not reached; concomitant androgen deprivation therapy was confirmed to be predictive of the worst MFS (hazard ratio 4.75, 95% confidence interval 1.52-14.8, P = 0.007). Late grade 1 and 2 rectal and bladder toxicity occurred in three (6%) and 13 (26%) patients, respectively. One patient experienced both grade 3 acute and chronic bladder toxicity.

CONCLUSION

Salvage SBRT re-irradiation after previous postoperative or definitive radiotherapy for local prostate cancer recurrence confirmed promising results in terms of oncological outcomes and the safety of this approach.

Magnetic Resonance-Guided Reirradiation for Local Recurrence Within the Prostate or in the Prostate Bed: Preliminary Results of a Prospective Registry Study

Purpose

This prospective registry study evaluated the feasibility of stereotactic magnetic resonance imaging (MRI)–guided radiation therapy for the local treatment of isolated prostate cancer recurrence within the gland or prostate bed after primary radiation therapy.

Methods and Materials

Patients with isolated recurrence without any regional or distant extension after treatment by external radiation therapy of the prostate gland/bed or by prostate brachytherapy were included. A 173-second Fast Imaging with Steady state Precession (TrueFISP) sequence was used for MRI simulation, and the gross tumor volume was delineated using multimodal images. The initial treatment plan varied from 27.5 Gy in 5 fractions to 38.7 Gy in 9 fractions and was adapted at each session, if necessary. The primary endpoint was acute toxicities (according to the Common Terminology Criteria for Adverse Events v5.0 criteria). Secondary endpoints were the effects of the adaptive treatment on target volume coverage, late toxicities, and oncologic events.

Results

Twenty patients were included. After a minimum follow-up of 6 months, grade 2 dysuria (from grade 1 at baseline; n = 1), grade 2 polyuria (n = 1), grade 1 urinary incontinence (n = 1), grade 1 urinary pain (n = 2), and grade 1 diarrhea (n = 1) were reported.

All initial treatment plans met the tumor coverage objectives, with a mean 95% planning target volume value of 95.7%. No plan exceeded the bladder and rectum dose constraints, but 8 exceeded the urethra dose constraints because of urethra proximity to the planning target volume. The initial plan was adapted in 7 patients (35%). The tumor coverage improved by 3.7% compared with the predicted plan (P = .0001) without increase in the dose to organs at risk. The biochemical control rate for the whole cohort was 75% (15/20 patients) including the 4 patients who received androgen-deprivation therapy.

Conclusions

MRI-guided reirradiation for isolated recurrence within the prostate or in the prostate bed appears to be safe with excellent dosimetric results.

[Ultra-hypofractionated radiotherapy for the treatment of localized prostate cancer: Results, limits and prospects]

Still an emerging approach a few years ago, stereotactic body radiation therapy (SBRT) has ranked as a valid option for the treatment of localized prostate cancer. Inherent properties of prostatic adenocarcinoma (low α/β) make it the perfect candidate. We propose a critical review of the literature trying to put results into perspective to identify their strengths, limits and axes of development. Technically sophisticated, the stereotactic irradiation of the prostate is well tolerated. Despite the fact that median follow-up of published data is still limited, ultra-hypofractionated radiotherapy seems very efficient for the treatment of low and intermediate risk prostate cancers. Data seem satisfying for high-risk cancers as well. New developments are being studied with a main interest in treatment intensification for unfavorable intermediate risk and high-risk cancers. Advantage is taken of the sharp dose gradient of stereotactic radiotherapy to offer safe reirradiation to patients with local recurrence in a previously irradiated area.

MR-Guided Hypofractionated Radiotherapy: Current Emerging Data and Promising Perspectives for Localized Prostate Cancer

Simple Summary

The biological features of prostate cancer as a tumor with a low alpha beta ratio have led clinicians to consider the use of higher doses per fraction, thus gaining an advantage both in terms of clinical outcomes and of logistic opportunities. To date, moderate hypofractionated schedules are supported by several international clinical guidelines. The subsequent step was represented by the adoption of extreme hypofractionated schedules, for which recent literature data report non-inferiority results for the five-fractions regimens. In this scenario, the recent introduction of MR-guided daily adaptive radiotherapy is a potential paradigm shift, given the ability to increase the resolution of the pelvis anatomy and to take into account of the daily variations in shape and size of the nearby healthy structures.

Abstract

In this review we summarize the currently available evidence about the role of hybrid machines for MR-guided radiotherapy for prostate stereotactic body radiotherapy. Given the novelty of this technology, to date few data are accessible, but they all report very promising results in terms of tolerability and preliminary clinical outcomes. Most of the studies highlight the favorable impact of on-board magnetic resonance imaging as a means to improve target and organs at risk identification with a consequent advantage in terms of dosimetric results, which is expected to relate to a more favorable toxicity pattern. Still, the longer treatment time per session may potentially affect the patient’s compliance to the treatment, although first quality of life assessment studies have reported substantial tolerability and no major impact on quality of life. Finally, in this review we hypothesize some future scenarios of further investigation, based on the possibility to explore the superior anatomy visualization and the role of daily adapted treatments provided by hybrid MR-Linacs.

Outcomes and toxicities of re-irradiation for prostate cancer: A systematic review on behalf of the Re-Irradiation Working Group of the Italian Association of Radiotherapy and Clinical Oncology (AIRO)

AIMS

The best therapeutic approach for local relapses of previously irradiated prostate cancer (PC) is still not defined. Re-irradiation (Re-I) could offer a chance of cure for highly selected patients, although high quality evidences are lacking. The aim of our study is to provide a literature review on efficacy and safety of Re-I.

METHODS

Only studies where Re-I field overlaps with previous radiotherapy were considered. To determine 2 and 4 years overall mortality (OM), 2 and 4 years biochemical failure (BF) and pooled acute and late G ≥ 3 toxicities rate, a meta-analysis over single arm study was performed.

RESULTS

Thirty-eight studies with 1194 patients were included. Median follow-up from Re-I was 30 months (10-94 months). Brachytherapy (BRT) was the most used Re-I technique (27 studies), followed by Stereotactic Body Radiotherapy (SBRT) (9) and External Beam Radiation Therapy (EBRT) (2). Re-I prescription doses ranged from 19 Gy in single HDR fraction to 145 Gy (interstitial BRT). The pooled 2 and 4 years OM rates were 2.1% (95%CI:1.1-3.7%, P < 0.001) and 12.5% (95%CI:8.1-19.5%; P < 0.001). The pooled 2 years BF rate was 24% (95% CI: 19.1-30.2%, P < 0.001). The pooled 4 years BF was 35.6% (95% CI: 28.7-44.3%, P < 0.001). The pooled result of G ≥ 3 acute toxicity was 1.4% (95%CI: 0.7-3%, P < 0.001). One hundred and three G ≥ 3 late adverse events were reported, with a pooled result of G ≥ 3 late toxicity of 8.7% (95%CI: 5.8-13%, P < 0.001).

CONCLUSIONS

Re-I of local failures from PC showed promising OM and biochemical control rates with a safe toxicity profile.

Prostate re-irradiation: current concerns and future perspectives

INTRODUCTION

To date, the optimal management of locally relapsed prostate cancer patients after an initial course of radiotherapy remains a matter of debate. In recent years, local approaches have been proposed as a therapeutic option, which may potentially delay the initiation of hormone therapy. In the case of external beam radiotherapy (EBRT), re-irradiation has been supported by growing evidence in the literature, mostly represented by extreme hypofractionated schedules delivered with stereotactic body radiotherapy (SBRT).

AREAS COVERED

We performed a systematic review of the literature using the PICO methodology to explore the available evidence regarding the use of EBRT in the setting of locally relapsed prostate cancer, both in terms of safety, tolerability and preliminary clinical outcomes.

EXPERT OPINION

Current literature data report the use of EBRT and particularly of SBRT for the safe and feasible re-treatment of locally recurrent prostate cancer after an initial treatment course of radiotherapy. When extreme hypofractionation is adopted, only occasional grade ≥3 late adverse events are reported. Despite the current lack of high-level evidence and the short follow-up, preliminary clinical outcomes are promising and allow clinicians to hypothesize further prospective studies to evaluate SBRT as an alternative to the early initiation of androgen-deprivation therapy.

Single‐fraction image‐guided robotic radiosurgery efficiently controls local prostate cancer recurrence after radical prostatectomy

Purpose

To assess the therapeutic potential of single‐fraction robotic stereotactic ablative body radiotherapy (SABR) in patients with locally recurrent prostate cancer (PC) after radical prostatectomy (RP).

Materials and methods

We included 35 patients with biochemical failure after RP with single‐site local recurrence in the prostate bed diagnosed by PSMA PET/CT. About 20/35 pts had previously received post‐surgical adjuvant radiation therapy.

High‐resolution multiparametric magnetic resonance imaging (mpMRI) for exact visualization of tumor tissue was performed at 1.5 (n = 23; Siemens Magnetom Aera) or 3 Tesla (n = 12; Siemens Magnetom VIDA, Siemens Healthineers, Erlangen, Germany). Using the MRI and PET/CT dataset for planning, SABR was carried out after ultrasound‐guided placement of a single gold fiducial marker at the site of tumor recurrence using a CyberKnife M6 unit (Accuray Inc., Sunnyvale, USA). Due to the high diagnostic accuracy of PSMA PET/CT and mpMRI, pre‐SABR biopsy of tumor tissue was not deemed necessary. PSMA PET/CT performed in median 88 days before SABR confirmed the absence of distant metastases. MpMRI was performed at a median of 22 days prior to the intervention. SABR was performed in a single fraction with a dose of 20 (5/35), 21 (27/35) or 22 (3/35) Gy. Follow‐up serum PSA was measured every 3 months thereafter.

Results

Median patient age was 72 years (57‐80 years) and median time from RP to SABR was 96.8 months (IQR, 69.3‐160.2). Median serum PSA before SABR was 1.38 ng/mL (IQR 0.75‐2.72). At 3 months, median PSA had dropped significantly in 27/35 patients to a median of 0.35 ng/mL (IQR 0.25‐0.68). At 6 months, 30/35 patients showed biochemical response to SABR, while five patients were progressing: three had systemic disease on PSMA PET/CT, while two patients had rising PSA values without a visible correlate on PET/CT. The median follow‐up time was 16 months. Grade 1 genitourinary (GU) toxicity was reported in 3/35 patients (9%) and grade 1 gastrointestinal (GI) toxicity in 2/35 patients (6%), respectively.

Conclusion

SABR is an efficient new treatment option in the management of single‐site local recurrent PC without the evidence of systemic disease; due to its very low toxicity, it is an alternative to surgical re‐treatment or other focal therapies. It can significantly delay the onset of androgen deprivation therapy (ADT) in biochemical failure after radical prostatectomy.

Minimally invasive strategies for the treatment of prostate cancer recurrence after radiation therapy: a systematic review

INTRODUCTION

The aim of this review was to conduct a comprehensive analysis of the role of minimally invasive salvage modalities in radio-recurrent prostate cancer and the associated clinical outcomes and toxicity profiles.

EVIDENCE ACQUISITION

A systematic review of the current literature was conducted through the Medline and NCBI PubMed, Scopus databases in January 2020. All papers published after 2000, concerning studies conducted on humans for radio-recurrent prostate cancer were considered for the review.

EVIDENCE SYNTHESIS

Overall, 545 studies were identified. After duplicate exclusion, initial screening, and eligibility evaluation, a total of 80 studies were included in the qualitative analysis, corresponding to a cohort of 6681 patients. The median age at initial diagnosis ranged from 59 to 75.5. Pre-treatment PSA ranged from 6.2 to 27.4 ng/mL. All patients underwent primary radiotherapy for localized prostate cancer. Cryotherapy, Brachytherapy, EBRT, HIFU were the minimally invasive options mostly used as salvage therapy. They showed to be promising approaches for recurrent prostate cancer (PCa) control, with acceptable toxicities.

CONCLUSIONS

Minimally invasive therapeutic options offer promising results in terms of biochemical control in the local recurrence setting. Unfortunately, the absence of high quality and comparative studies makes it difficult to establish which method is the best in terms of oncological and safety outcomes.

Repeat Radiation for Local Recurrence of Head and Neck Tumors and in Prostate Cancer

BACKGROUND

Recent advances in diagnostic methods and in radiotherapy now increasingly enable repeat radiotherapy with curative intent for the treatment of previously irradiated lesions. In this review, we present data on oncological outcomes and on acute and late sequelae, as far as these are currently known, in patients with head and neck tumors (HNT) or prostate cancer (PCa) who underwent repeat radiotherapy after prior radiotherapy with curative intent.

METHODS

This review is based on clinical series with over 20 patients that were published between May 1998 and April 2018 (HNT) or between October 1998 and October 2018 (PCa) and were retrieved by a search in the PubMed database.

RESULTS

Most of the clinical series retrieved were retrospective and uncontrolled. There were 16 studies that included 2678 patients with recurrent head and neck tumors, and 8 that included 245 patients with recurrent prostate cancer. In patients with squamous cell carcinoma of the head and neck, intensity-modulated radio - therapy (IMRT) and stereotactic body radiotherapy (SBRT) yielded three-year survival rates of 47-57% but also produced substantial acute and late adverse effects. Most of the studies concerning recurrent PCa involved small patient groups. In these studies, repeat radiotherapy with SBRT yielded tumor control rates of 40-80% after 11-24 months of follow-up, with only mild acute toxicity.

CONCLUSION

Although no comparative studies are available, it seems that modern external beam radiotherapy techniques can be used for repeat radiotherapy of locally recurrent head and neck tumors with curative intent after careful patient selection. Repeat radiotherapy of PCa must still be considered experimental, but initial results from small-scale trials are encouraging. The long-term adverse effects cannot yet be accessed. Patients should be selected by an interdisciplinary tumor board. This type of treatment is generally carried out in a specialized center.

A Novel Salvage Option for Local Failure in Prostate Cancer, Reirradiation Using External Beam or Stereotactic Radiation Therapy: Systematic Review and Meta-Analysis

Purpose

Reirradiation (re-RT) using external beam radiation therapy (EBRT) is a novel salvage strategy for local failure in prostate cancer. We performed a systematic review describing oncologic and toxicity outcomes for salvage EBRT/stereotactic radiation therapy (SBRT) re-RT.

Methods and Materials

A International Prospective Register of Systematic Reviews registered (#141466) systematic review, meta-analysis, and meta-regression was conducted using preferred reporting items for systematic reviews and meta-analyses guidelines. PubMed and EMBASE were searched from inception through September 2019. Outcome measures included local control (LC), biochemical relapse free survival (BRFS), and ≥grade 3 genitourinary (GU)/gastrointestinal (GI) toxicity. EBRT and SBRT data were collected separately. Meta-regression explored disease and toxicity outcomes as a function of equivalent dose in 2 Gy fractions (EQD2), length of follow-up, and partial versus whole prostate reirradiation.

Results

Nineteen studies representing 13 cohorts were included (428 patients). Weighted mean follow-up was 26.1 months. Median re-RT EQD2 was 77.1 Gy (α/β = 1.5), with 92% of patients receiving SBRT, 52.1% of patients receiving partial prostate re-RT, and 30.1% of patients receiving androgen deprivation therapy with re-RT. LC was 83.2% (95% confidence interval [CI], 75.5%-90.9%) and BRFS was 59.3% (47.9%-70.7%). Reported late toxicity ≥grade 3 was 3.4% (95% CI, 1.0%-5.8%) for GU and 2.0% (95% CI, 0.1%-4.0%) for GI. Meta-regression found higher LC, BRFS, and reported GU/GI toxicity with increasing EQD2, with partial prostate re-RT associated with less reported GU/GI toxicity and no detriment to LC and BRFS.

Conclusions

Salvage re-RT using EBRT, particularly with SBRT, is an emerging technique to treat isolated local failure of prostate cancer. With short-term follow-up, LC, BRFS, and reported toxicities appear reasonable, although further follow-up is required before definitive statements on late toxicities can be made. Our review is limited by incomplete reporting of androgen deprivation therapy use in the primary literature. Further prospective studies and longer follow-up are needed before considering re-RT as standard practice.

Salvage reirradiation for local prostate cancer recurrence after radiation therapy. For who? When? How?

PURPOSE

Literature review reporting results of salvage brachytherapy and stereotactic body radiotherapy for prostate recurrence only after radiotherapy for prostate cancer.

MATERIALS AND METHODS

A total of 38 studies (including at least 15 patients per study) were analysed: 19 using low-dose-rate brachytherapy, nine high-dose-rate brachytherapy and ten stereotactic body radiotherapy. Only five studies were prospective. The median numbers of patients were 30 for low-dose-rate brachytherapy, 34 for high-dose-rate brachytherapy, and 30 for stereotactic body radiotherapy. The median follow-up were 47months for low-dose-rate brachytherapy, 36months for high-dose-rate brachytherapy and 21months for stereotactic body radiotherapy.

RESULTS

Late genitourinary toxicity rates ranged, for grade 2: from 4 to 42% for low-dose-rate brachytherapy, from 7 to 54% for high-dose-rate brachytherapy and from 3 to 20% for stereotactic body radiotherapy, and for grade 3 or above: from 0 to 24% for low-dose-rate brachytherapy, from 0 to 13% for high-dose-rate brachytherapy and from 0 to 3% for grade 3 or above (except 12% in one study) for stereotactic body radiotherapy. Late gastrointestinal toxicity rates ranged, for grade 2: from 0 to 6% for low-dose-rate brachytherapy, from 0 to 14% for high-dose-rate brachytherapy and from 0 to 11% for stereotactic body radiotherapy, and for grade 3 or above: from 0 to 6% for low-dose-rate brachytherapy, and from 0 to 1% for high-dose-rate brachytherapy and stereotactic body radiotherapy. The 5-year biochemical disease-free survival rates ranged from 20 to 77% for low-dose-rate brachytherapy and from 51 to 68% for high-dose-rate brachytherapy. The 2- and 3-year disease-free survival rates ranged from 40 to 82% for stereotactic body radiotherapy. Prognostic factors of biochemical recurrence have been identified.

CONCLUSION

Despite a lack of prospective data, salvage reirradiation for prostate cancer recurrence can be proposed to highly selected patients and tumours. Prospective comparative studies are needed.