Helical tomotherapy re-irradiation for patients affected by local radiorecurrent prostate cancer

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.

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.

PROLAPSE: survey about local prostate cancer relapse salvage treatment with external beam re-irradiation: results of the Italian Association of Radiotherapy and Clinical Oncology (AIRO)

PURPOSE

We herein present the results of the first Italian Association of Radiotherapy and Clinical Oncology (AIRO) survey regarding salvage external beam re-irradiation of local prostate cancer relapse named PROLAPSE.

METHODS

A questionnaire with 12 items was administered to the 775 Italian radiation oncologist members of the AIRO.

RESULTS

One hundred of the members completed the survey. The survey highlighted that 59% of the participants are currently performing prostate re-EBRT, while nearly two-thirds (65%) affirmed that they are taking into consideration the procedure in case of intraprostatic relapse. Regarding the clinical target volume (CTV), only a minority (16%) declared to always prefer the partial prostate re-irradiation, while a consistent portion (nearly two-thirds) relied on clinical considerations of the choice towards partial or whole gland irradiation. The main techniques used for re-irradiation resulted to be intensity-modulated RT (IMRT)/volumetric modulated arc therapy (VMAT) and SBRT, having received approximately 40% of responses each. Regarding the criteria for patients' selection, more than 75% of responders agreed on the use of positron emission tomography (PET)/computed tomography (CT)-choline to exclude distant metastases and of multiparametric magnetic resonance imaging (mp-MRI) to detect intraprostatic recurrence. A sufficient timeframe (> 3 years) between primary RT and reirradiation was indicated by more than half of participants as an important driver in decision-making, while histological confirmation of the relapse was considered not essential by more than two-thirds. For the use of concomitant androgen deprivation therapy (ADT), most AIRO members (79%) agreed that the prescription should be based on a case-by-case analysis. Extreme hypofractionation (> 5 Gy/fraction) was preferred by the majority (52%) of the AIRO members. In most centers (more than 74%), the planning dose-volume constraints were generally extrapolated from the published data. In half of the cases, the interviewed responders affirmed that no major gastrointestinal (GI) and genitourinary (GU) toxicities were registered in the follow-up of their re-EBRT patients. Bladder complications represented the most commonly observed form of toxicity, with an incidence of 67%.

CONCLUSION

This first AIRO survey about salvage prostate re-EBRT provides an interesting snapshot and suggests increasing interest in re-EBRT patients in Italy. Consensus about some aspects of patients' selection, the necessity of biopsy, fractionation, and highly selective techniques seems feasible, but other key points such as irradiated volume, dosimetry parameters, and hormonal treatment association need to be clarified.