Later Outcomes and Alpha/Beta Estimate From Hypofractionated Conformal Three-Dimensional Radiotherapy Versus Standard Fractionation for Localized Prostate Cancer

21 Gy single fraction prostate HDR brachytherapy: 5-year results of a single institution prospective pilot study

PURPOSE

To present the outcome and toxicity results of a prospective trial of 21 Gy single fraction high-dose-rate (HDR) brachytherapy for men with low- or intermediate-risk prostate cancer.

METHODS AND MATERIALS

Patients were treated according to an IRB-approved prospective study of single fraction HDR brachytherapy. Eligible patients had low- or intermediate-risk prostate cancer with tumor stage ≤ T2b, PSA ≤ 15, and Gleason score ≤ 7. Patients underwent trans-rectal ultrasound-guided trans-perineal implant of the prostate followed by single fraction HDR brachytherapy to a dose of 21 Gy. The primary endpoint was grade ≥ 2 urinary/GI toxicity rates.

RESULTS

Twenty-six patients were enrolled with a median follow up of 5.1 years and median age of 64 years. 88.5% of patients had T1 disease, 15.4% had Gleason score 6 (84.6% Gleason 7), and median pre-treatment PSA was 5.0 ng/mL. Acute and chronic grade ≥ 2 urinary toxicity rates were 38.5% and 38.5%, respectively. There were no grade ≥ 2 acute or chronic GI toxicities. Six (23.1%) patients experienced biochemical failure, six (23.1%) patients experienced radiographic local failure, and five (19.2%) patients had biopsy-proven local failure. No patients developed regional lymph node recurrence or distant metastasis. 5-year overall survival and cause-specific survival were 96.2% and 100%, respectively.

CONCLUSIONS

21 Gy single fraction HDR brachytherapy was associated with modestly higher-than-anticipated chronic urinary toxicity, as well as high biochemical and local failure rates. The results from this prospective pilot study do not support the use of this regimen in standard clinical practice.

Revolutionizing localized prostate cancer treatment: Stereotactic radiotherapy "Moroccan experience"

INTRODUCTION

Prostate cancer is the most common urological cancer, and its incidence  is increasing. Radical prostatectomy and radiotherapy are theprimary treatments for localized forms. Stereotactic Body RadioTherapy (SBRT), a new and innovative therapy, has been validated for some cancer localizations but not yet for localized prostate cancer. Our study aims to report the efficacy and tolerance results of SBRT for localized prostate cancer.

MATERIALS AND METHODS

This is a retrospective study of 27 patients with localized prostate cancer (CaP) who were treated with SBRT in our department from 2017 to 2021 using transponders for tumor tracking. The dose was 36.25 Gy delivered in five fractions of 7.25 Gy. The delineation and doses of organs at risk were determined based on the recommendations of the SFRO and the TG101 report of medical physics. All patients were treated using a latest-generation linear accelerator (True Beam STXÒ).

RESULTS

Acute toxicities were observed in 33.3% of cases, with 22.2% grade 1 or 2 genitourinary (GU) and no grade 3 while 11.1% gastrointestinal (GI) toxicities were reported as grade 1-2 (7.4%) and one case grade 3 (3.7%). Late grade 1 or 2 GU toxicity was observed in 14.84% of cases, with no reports of late GI toxicity. After a 26-month follow-up period, the biochemical failure-free survival rate was 92.6%.

CONCLUSIONS

The results of our study are consistent with the existing literature and support the safety and effectiveness of SBRT as a treatment option for localized prostate cancer (CaP). In the United States, both ASTRO and the NCCN recognize SBRT as a valid treatment option for localized CaP. Ongoing phase III trials are being conducted to further substantiate these long-term results and to establish SBRT as the future standard of care for localized CaP.

Hypofractionated, Dose Escalation Radiation Therapy for High-Risk Prostate Cancer: The Safety Analysis of the Prostate Cancer Study-5, a Groupe de Radio-Oncologie Génito-Urinaire de Quebec Led Phase 3 Trial

PURPOSE

The low α\β ratio of 1.2 to 2 for prostate cancer (PCa) suggests high radiation-fraction sensitivity and predicts a therapeutic advantage of hypofractionated (HF) radiation therapy (RT). To date, no phase 3 randomized clinical trial has compared moderately HF RT with standard fractionation (SF) exclusively in high-risk PCa patients. We are reporting the safety of moderate HF RT in high-risk PCa in an initially noninferiority-designed phase 3 clinical trial.

METHODS AND MATERIALS

From February 2012 to March 2015, 329 high-risk PCa patients were randomized to receive either SF or HF RT. All patients received neoadjuvant, concurrent, and long-term adjuvant androgen deprivation therapy. Standard fractionation RT consisted of 76 Gy in 2 Gy per fraction to the prostate, where 46 Gy was delivered to the pelvic lymph nodes. Hypofractionated RT included concomitant dose escalation of 68 Gy in 2.72 Gy per fraction to the prostate and 45 Gy in 1.8 Gy per fraction to the pelvic lymph nodes. The coprimary endpoints were acute and delayed toxicity at 6 and 24 months, respectively. The trial was originally designed as a noninferiority with a 5% absolute margin. Given the lower-than-expected toxicities in both arms, the noninferiority analysis was completely dropped.

RESULTS

Of the 329 patients, 164 were randomized to the HF and 165 to the SF arms. In total, there were more grade 1 or worse acute gastrointestinal (GI) events in the HF arm, 102 versus 83 events in the HF and SF arm, respectively (P = .016). This did not remain significant at 8 weeks of follow-up. There were no differences in grade 1 or worse acute GU events in the 2 arms, 105 versus 99 events in the HF and SF arm, respectively (P = .3). At 24 months, 12 patients in the SF arm and 15 patients in the HF arm had grade 2 or worse delayed GI-related adverse events (hazard ratio, 1.32; 95% CI, 0.62-2.83; P = .482). There were 11 patients in the SF arm and 3 patients in the HF arm with grade 2 or higher delayed genitourinary (GU) toxicities (hazard ratio, 0.26; 95% CI, 0.07-0.94; P = .037). There were 3 grade 3 GI and one grade 3 GU delayed toxicities in the HF arm and 3 grade 3 GU and no grade 3 GI toxicities in the SF arm. No grade 4-toxicities were reported.

CONCLUSIONS

This is the first study of moderate HF dose-escalated RT in exclusively high-risk patients with prostate cancer treated with long-term androgen deprivation therapy and pelvic RT. Although our data were not analyzed as a noninferiority, our results demonstrate that moderately HF RT is well-tolerated, similar to SF RT at 2 years, and could be considered an alternative to SF RT.

Prostate Cancer Treatment-Related Toxicity: Comparison between 3D-Conformal Radiation Therapy (3D-CRT) and Volumetric Modulated Arc Therapy (VMAT) Techniques

Objective: This paper illustrates the results of a mono-institutional registry trial, aimed to test whether gastrointestinal (GI) and genitourinary (GU) toxicity rates were lower in localized prostate cancer patients treated with image-guided volumetric modulated arc therapy (IG-VMAT) compared to those treated with IG-3D conformal radiation therapy (IG-3DCRT). Materials and Methods: Histologically proven prostate cancer patients with organ-confined disease, treated between October 2008 and September 2014 with moderately hypofractionated radiotherapy, were reviewed. Fiducial markers were placed in the prostate gland by transrectal ultrasound guide. The prescribed total dose was 70 Gy in 28 fractions. The mean and median dose volume constraints for bladder and rectum as well as total volume of treatment were analyzed as potentially prognostic factors influencing toxicity. The Kaplan−Meier method was applied to calculate survival. Results: Overall, 83 consecutive patients were included. Forty-two (50.6%) patients were treated with 3D-CRT and 41 (49.4%) with the VMAT technique. The median follow-up for toxicity was 77.26 months for the whole cohort. The VMAT allowed for a dose reduction to the rectum and bladder for the large majority of the considered parameters; nonetheless, the only parameter correlated with a clinical outcome was a rectal dose limit V66 > 8.5% for late GI toxicity G ≥ 2 (p = 0.045). Rates of G ≥ 2 toxicities were low among the whole cohort of these patients treated with IGRT. The analysis for rectum dose volume histograms (DVHs) showed that a severe (grade ≥ 2) late GI toxicity was related with the rectal dose limit V66 > 8.5% (p = 0.045). Conclusions: This study shows that moderate hypofractionation is feasible and safe in patients with intermediate and high-risk prostate cancer. Daily IGRT may decrease acute and late toxicity to organs at risk and improve clinical benefit and disease control rate, cutting down the risk of PTV geographical missing. The adoption of VMAT allows for promising results in terms of OAR sparing and a reduction in toxicity that, also given the small sample, did not reach statistical significance.

Androgen Flare after LHRH Initiation Is the Side Effect That Makes Most of the Beneficial Effect When It Coincides with Radiation Therapy for Prostate Cancer

Simple Summary

Prostate cancer tumor growth is stimulated by androgens. Surgical castration or medical castration using long-acting luteinizing hormone-releasing hormone (LHRH) agonists or antagonists is the backbone of the treatments of metastatic disease. Treatment of locally advanced prostate cancer was accomplished with radiation therapy alone until multiple studies showed that combining radiation therapy with LHRH agonists results in significant survival benefit. While the goal of the use of LHRH agonists was to suppress testosterone levels during radiation, we show, through review of previous studies, that survival benefit was achieved only when LHRH was initiated during the course of radiation, and thus androgen flare during the first 1–3 weeks after the initiation of LHRH is most likely the reason for higher survival. Androgens drive tumor cells into mitosis, and mitotic death is the dominant mechanism of tumor cell kill by radiation.

Abstract

Treatment of metastatic prostate cancer was historically performed via bilateral orchiectomy to achieve castration. An alternative to surgical castration is the administration of subcutaneous recombinant luteinizing hormone-releasing hormone (LHRH). LHRH causes the pituitary gland to produce luteinizing hormone (LH), which results in synthesis and secretion of testosterone from the testicles. When LHRH levels are continuously high, the pituitary gland stops producing LH, which results in reduced testosterone production by the testicles. Long-acting formulations of LHRH were developed, and its use replaced surgical orchiectomy in the vast majority of patients. Combining LHRH and radiation therapy was shown to increase survival of prostate cancer patients with locally advanced disease. Here, we present a hypothesis, and preliminary evidence based on previous randomized controlled trials, that androgen surge during radiation, rather than its suppression, could be responsible for the enhanced prostate cancer cell kill during radiation. Starting LHRH agonist on the first day of radiation therapy, as in the EORTC 22863 study, should be the standard of care when treating locally advanced prostate cancer. We are developing formulations of short-acting LHRH agonists that induce androgen flare, without subsequent androgen deprivation, which could open the door for an era in which locally advanced prostate cancer could be cured while patients maintain potency.

Spatiotemporal optimisation of prostate intensity modulated proton therapy (IMPT) treatments

Objective. In intensity modulated particle therapy (IMPT), the adoption of spatially and temporally heterogeneous dose distributions allows to decouple the fractionation scheme from the patient anatomy, so that an hypofractionated schedule can be selectively created inside the tumour, while simultaneously exploiting the fractionation effect in the healthy tissues. In this paper, the authors show the reproducibility of the method on a set of prostate patients, quantifying the dependencies of the achievable benefit with respect to conventional and hypofractionated schemes and the sensitivity of the method to setup errors and range uncertainty. Approach. On a cohort of 9 patients, non-uniform IMPT plans were optimised and compared to conventional and hypofractionated schedules. For each patient, the comparison of the three strategies has been based on the output of the cost function used to optimise the treatments. The analysis has been repeated considering different α/β ratios for the tumour, namely 1.5, 3 and 4.5 Gy. For a single patient, setup errors and beam range uncertainty have been analysed: the plans, for each optimisation strategy, have been iteratively forward planned 500 times with randomly varying the patient position in each fraction, and 200 times for systematic range shift. Main results. An average 10% benefit has been shown for the lowest α/β ratio considered for the tumour, where the non-uniform schedule generally converges to hypofractionation; the benefit decreases to 5%–7% for higher α/β ratios, for which the non-uniform schedule always showed better outcomes with respect to the other fractionation schedules. An increased sensitivity to uncertainty, especially for setup errors, has been shown, which can be associated to the spatial non-uniformity of the dose distributions peculiar of the spatiotemporal plans. Significance. This work represents the first investigation of spatiotemporal fractionation for prostate cancer and the beginning of further investigations before clinical implementation can be considered.

Heuristic estimation of the α/β ratio for a cohort of Mexican patients with prostate cancer treated with external radiotherapy techniques

Background

The aim of the study was to Estimate and compare the radiobiological ratio α/β with the heuristic method for a cohort of Mexican patients with prostate cancer (PCa) who were treated with external radiotherapy (RT) techniques at three Hospital Institutions in Mexico City. With the Kaplan-Meier technique and the Cox proportional hazards model, the biochemical relapse-free survival (bRFS) is determined and characterized for cohorts of Mexican patients with PCa who received treatment with external RT. Using these clinical outcomes, the radiobiological parameter α/β is determined using the heuristic methodology of Pedicini et. al.

Materials and methods

The α/β is calculated from the survival curves for different treatment schemes implemented at three distinct hospitals. The Pedicini's techniques allow to determine the parameters α/β, k and N ₀ when treatments are not radiobiologically equivalent, therefore, are built up of a set of curved pairs for the biologically effective dose (BED) versus the ratio α/β, where the ratio is given by the intersection for each pair of curves.

Results

Six different values of α/β were found: the first α/β = 2.46 Gy, the second α/β = 3.30 Gy, the third for α/β = 3.25 Gy, the fourth α/β = 3.24 Gy, the fifth α/β = 3.38 Gy and the last α/β = 4.08 Gy. These values can be explained as follows: a) The bRFS of the schemes presents a statistical variation; b) The absorbed doses given to the patient present uncertainties on the physical dosimetry that are not on the modeling; c) Finally, in the model for the bRFS of Eq. (3), there are parameters that have to be considered, such as: the number of clonogenic tumor cells N ₀ , the overall treatment time (OTT), the kick-off time for tumor repopulation T _k and the repopulation doubling time. Therefore, the mean value to α/β for all schemes has an average value of 3.29 (± 0.52) Gy.

Conclusions

The value of α / β ¯ = 3.29   ( ± 0.52 )   Gy is determined from cohorts of Mexican patients with PC a treated with external radiotherapy using the time-dependent LQ model, which is a higher value with respect to the "dogma" value of α/β 1.5 Gy obtained with the LQ model without temporal dependence. Therefore, there is a possibility of optimizing treatments radiobiologically and improving the results of bRFS in Mexican patients with PCa treated with external radiotherapy.

Prostate hypofractionated radiotherapy (62Gy at 3.1Gy per fraction) with injection of hyaluronic acid: final results of the RPAH1 study

OBJECTIVES

The present multicenter Phase II study evaluated the rate of late grade ≥2 gastrointestinal (GI) toxicities at 3 years, after hypofractionated radiotherapy (HFR) of prostate cancer with injection of hyaluronic acid (HA) between the prostate and the rectum.

METHODS

Between 2010 and 2013, 36 patients with low- or intermediate-risk prostate cancer were treated by HFR/IMRT-IGRT. 20 fractions of 3.1 Gy were delivered, 5 days per week for a total dose of 62 Gy. A transperineal injection of 10cc of HA was performed between the rectum and the prostate. Late toxicities were evaluated between 3 and 36 months after the end of treatment (CTCAE v4).

RESULTS

Median pretreatment prostate-specific antigen was 8 ng ml-1. Among the 36 included patients, 2 were not evaluated because they withdrew the study in the first 3 months of follow-up, and 4 withdrew between 3 and 36 months, the per protocol population was therefore composed.Late grade ≥2 GI toxicities occurred in 4 (12%) patients with 3 (9%) Grade 2 rectal bleedings and one diarrhoea. Therefore, the inefficacy hypothesis following Fleming one-stage design cannot be rejected. None of the patients experienced late Grade 3-4 toxicities. Among the 30 patients completing the 36 months' visit, none still had a grade ≥2 GI toxicity. Late grade ≥2 genitourinary (GU) toxicities occurred in 14 (41%) patients. The most frequent toxicities were dysuria and pollakiuria. Four patients still experienced a grade ≥2 GU toxicity at 36 months.The biochemical relapse rate (nadir +2 ng ml-1) was 6% (2 patients). Overall, HA was very well tolerated with no pain or discomfort.

CONCLUSION

Despite the inefficacy of HA injection was not rejected, we observed the absence of Grade 3 or 4 rectal toxicity as well as a rate of Grade 2 rectal bleeding below 10% at 36 months of follow-up. Late urinary toxicities are the most frequent but the rate decreases largely at 3 years.

ADVANCES IN KNOWLEDGE

With an injection of HA, hypofractionated irradiation in 4 weeks is well tolerated with no Grade 3 or 4 GI toxicity and a rate of Grade 2 rectal bleeding below 10% at 36 months of follow-up.

Cellular Radiosensitivity of Soft Tissue Sarcoma

Currently, all soft tissue sarcomas (STS) are irradiated by the same regimen, disregarding possible subtype-specific radiosensitivities. To gain further insight, cellular radiosensitivity was investigated in a panel of sarcoma cell lines. Fourteen sarcoma cell lines, derived from synovial sarcoma, leiomyosarcoma, fibrosarcoma and liposarcoma origin, were submitted to clonogenic survival assays. Cells were irradiated with single doses from 1-8 Gy and surviving fraction (SF) was calculated from the resulting response data. Alpha/beta (α/β) ratios were inferred from radiation-response curves using the linear-quadratic (LQ)-model. Cellular radiosensitivities varied largely in this panel, indicating a considerable degree of heterogeneity. Surviving fraction after 2 Gy (SF2) ranged from 0.27 to 0.76 with evidence of a particular radiosensitive phenotype in only few cell lines. D37% on the mean data was 3.4 Gy and the median SF2 was 0.52. The median α/β was 4.9 Gy and in six cell lines the α/β was below 4 Gy. A fairly homogeneous radiation response was observed in myxoid liposarcoma cell lines with SF2 between 0.64 and 0.67. Further comparing sarcomas of different origin, synovial sarcomas, as a group, showed the lowest SF2 values (mean 0.35) and was significantly more radiosensitive than myxoid liposarcomas and leiomyosarcomas (P = 0.0084 and 0.024, respectively). This study demonstrates a broad spectrum of radiosensitivities across STS cell lines and reveals subtype-specific radiation responses. The particular cellular radiosensitivity of synovial sarcoma cells supports consideration of the different sarcoma entities in clinical studies that aim to optimize sarcoma radiotherapy.

Standard versus hypofractionated intensity-modulated radiotherapy for prostate cancer: assessing the impact on dose modulation and normal tissue effects when using patient-specific cancer biology

Hypofractionation of prostate cancer radiotherapy achieves tumour control at lower total radiation doses, however, increased rectal and bladder toxicities have been observed. To realise the radiobiological advantage of hypofractionation whilst minimising harm, the potential reduction in dose to organs at risk was investigated for biofocused radiotherapy. Patient-specific tumour location and cell density information were derived from multiparametric imaging. Uniform-dose plans and biologically-optimised plans were generated for a standard schedule (78 Gy/39 fractions) and hypofractionated schedules (60 Gy/20 fractions and 36.25 Gy/5 fractions). Results showed that biologically-optimised plans yielded statistically lower doses to the rectum and bladder compared to isoeffective uniform-dose plans for all fractionation schedules. A reduction in the number of fractions increased the target dose modulation required to achieve equal tumour control. On average, biologically-optimised, moderately-hypofractionated plans demonstrated 15.3% (p-value: <0.01) and 23.8% (p-value: 0.02) reduction in rectal and bladder dose compared with standard fractionation. The tissue-sparing effect was more pronounced in extreme hypofractionation with mean reduction in rectal and bladder dose of 43.3% (p-value: < 0.01) and 41.8% (p-value: 0.02), respectively. This study suggests that the ability to utilise patient-specific tumour biology information will provide greater incentive to employ hypofractionation in the treatment of localised prostate cancer with radiotherapy. However, to exploit the radiobiological advantages given by hypofractionation, greater attention to geometric accuracy is required due to increased sensitivity to treatment uncertainties.

Can radiation-induced lower urinary tract disease be ameliorated in patients treated for pelvic organ cancer: ICI-RS 2019?

Aims

This article reviews the clinical outcomes and basic science related to negative effects of radiotherapy (RT) on the lower urinary tract (LUT) when used to treat pelvic malignancies.

Methods

The topic was discussed at the 2019 meeting of the International Consultation on Incontinence―Research Society during a “think tank” session and is summarized in the present article.

Results

RT is associated with adverse effects on the LUT, which may occur during treatment or which can develop over decades posttreatment. Here, we summarize the incidence and extent of clinical symptoms associated with several modes of delivery of RT. RT impact on normal tissues including urethra, bladder, and ureters is discussed, and the underlying biology is examined. We discuss innovative in vivo methodologies to mimic RT in the laboratory and their potential use in the elucidation of mechanisms underlying radiation‐associated pathophysiology. Finally, emerging questions that need to be addressed through further research are proposed.

Conclusions

We conclude that RT‐induced negative effects on the LUT represent a significant clinical problem. Although this has been reduced with improved methods of delivery to spare normal tissue, we need to (a) discover better approaches to protect normal tissue and (b) develop effective treatments to reverse radiation damage.

Biological dose summation of intensity-modulated arc therapy and image-guided high-dose-rate interstitial brachytherapy in intermediate- and high-risk prostate cancer

Purpose

To present an alternative method for summing biologically effective doses of intensity-modulated arc therapy (IMAT) as teletherapy (TT), with interstitial high-dose-rate (HDR) brachytherapy (BT) boost in prostate cancer. Total doses using IMAT boost was compared with BT boost using our method.

Material and methods

Initially, 25 IMAT TT plus interstitial HDR-BT plans were included, and additional plans using IMAT TT boost were created. The prescribed dose was 2/44 Gy to the whole pelvis, 2/60 Gy to the prostate and seminal vesicles, and 1 × 10 Gy BT or 2/18 Gy IMAT TT to the prostate. Teletherapy computed tomography (CT) was registered with ultrasound (US) of BT, and the most exposed volume of critical organs in BT were identified on these CT images. The minimal dose of these from IMAT TT was summed with their BT dose, and these EQD₂ doses were compared using BT vs. IMAT TT boost. This method was compared with uniform dose conception (UDC).

Results

D₉₀ of the prostate was significantly higher with BT than with IMAT TT boost: 99.3 Gy vs. 77.9 Gy, p = 0.0034. The D₂ to rectum, bladder, and hips were 50.3 Gy vs. 76.8 Gy (p = 0.0117), 64.7 Gy vs. 78.3 Gy (p = 0.0117), and 41.9 Gy vs. 50.6 Gy (p = 0.0044), while D_0.1 to urethra was 96.1 Gy vs. 79.3 Gy (p = 0.0180), respectively. UDC overestimated D₂ (rectum) by 37% (p = 0.0117), D₂ (bladder) by 5% (p = 0.0214), and underestimated D_0.1 (urethra) by 1% (p = 0.0277).

Conclusions

Based on our biological dose summation method, the total dose of prostate is higher using BT boost than the IMAT. BT boost yields lower rectum, bladder, and hips doses, but higher dose to urethra. UDC overestimates rectum and bladder dose and underestimates the dose to urethra.

Whole Pelvic Radiotherapy With Stereotactic Body Radiotherapy Boost vs. Conventionally Fractionated Radiotherapy for Patients With High or Very High-Risk Prostate Cancer

Background: Whole pelvic radiotherapy (WPRT) with stereotactic body radiotherapy (SBRT) boost has been shown to be effective in patients with high-risk prostate cancer (PC). However, no study has directly compared the efficacy of WPRT with SBRT boost with that of conventionally fractionated radiotherapy (CFRT). We compared the clinical outcomes between CFRT and WPRT with SBRT boost in patients with high or very high-risk PC (National Comprehensive Cancer Network definition).

Methods: In total, 132 patients treated with CFRT and 121 patients treated with WPRT followed by SBRT boost were retrospectively analyzed. For the CFRT group, the prescribed dose range was 74–79.2 Gray (Gy) administered at 1.8–2 Gy per fraction. For WPRT with SBRT boost, the prescribed doses were 45 Gy administered in 25 fractions to the whole pelvis followed by 21 Gy boost (3 fractions of 7 Gy each) to prostate and seminal vesicles. The overall survival (OS) and biochemical failure (Phoenix definition) free survival (bFFS) were assessed by using the Kaplan–Meier method or the Cox proportional hazards regression model. The gastrointestinal (GI) and genitourinary (GU) tract toxicity were assessed using the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) v3.0.

Results: The estimated 4-years overall survival in the CFRT and WPRT with SBRT boost groups was 91.6 and 97.7%, respectively (P = 0.18). The estimated 4-years biochemical failure-free survival in the CFRT and WPRT with SBRT boost groups was 89.1 and 93.9%, respectively (P = 0.41). No acute grade 3 or higher GI and GU toxicity was observed in both groups. Late grade 3 GI and GU toxicity occurred in 2.3 and 2.3% in the CFRT group, and in 1.7 and 0.8% in the WPRT with SBRT boost group, respectively. There was no significant between-group difference with respect to acute or late toxicity.

Conclusions: In patients with high or very high-risk localized PC, compared with CFRT, WPRT with SBRT boost resulted in similar biochemical-free and overall survival rate with minimal toxicity. WPRT with SBRT boost is a feasible option for patients with high or very high-risk PC.

Biochemical relapse free survival rate in patients with prostate cancer treated with external radiotherapy: outcomes obtained at the CMN Siglo XXI Hospital de Oncología, CMN 20 de Noviembre and Hospital General de México of the México City

Aim

Biochemical relapse-free survival (bRFS) rate is determined by a cohort of Mexican patients (n = 595) with prostate cancer who received treatment with external radiotherapy.

Background

Patients with prostate cancer were collected from CMN Siglo XXI (IMSS), CMN 20 de Noviembre (ISSSTE), and Hospital General de México (HGM). For the IMSS, 173 patients that are treated with three-dimensional conformal radiation therapy (3D-CRT) and 250 with SBRT, for the ISSSTE 57 patients are treated with 3D-CRT and on the HGM 115 patients are managed with intensity modulated radiation therapy (IMRT). The percentage of patients by risk group is: low 11.1%, intermediate 35.1% and high 53.8%. The average follow-up is 39 months, and the Phoenix criterion was used to determine the bRFS.

Materials and methods

The Kaplan-Meier technique for the construction of the survival curves and, the Cox proportional hazards to model the cofactors.

Results

(a) The bRFS rates obtained are 95.9% for the SBRT (7 Gy fx, IMSS), 94.6% for the 3D-CRT (1.8 Gy fx, IMSS), 91.3% to the 3D-CRT (2.65 Gy fx, IMSS), 89.1% for the SBRT (7.25 Gy fx, IMSS), 88.7% for the IMRT (1.8 Gy fx, HGM) %, and 87.7% for the 3D-CRT (1.8 Gy fx, ISSSTE). (b) There is no statistically significant difference in the bRFS rates by fractionation scheme, c) Although the numerical difference in the bRFS rate per risk group is 95.5%, 93.8% and 89.1% for low, intermediate and high risk, respectively, these are not statistically significant.

Conclusions

The RT techniques for the treatment of PCa are statistically equivalent with respect to the bRFS rate. This paper confirms that the bRFS rates of Mexican PCa patients who were treated with conventional vs. hypofractionated schemes do not differ significantly.

Hypofractionation for clinically localized prostate cancer

BACKGROUND

Using hypofractionation (fewer, larger doses of daily radiation) to treat localized prostate cancer may improve convenience and resource use. For hypofractionation to be feasible, it must be at least as effective for cancer-related outcomes and have comparable toxicity and quality of life outcomes as conventionally fractionated radiation therapy.

OBJECTIVES

To assess the effects of hypofractionated external beam radiation therapy compared to conventionally fractionated external beam radiation therapy for men with clinically localized prostate cancer.

SEARCH METHODS

We searched CENTRAL, MEDLINE (Ovid), Embase (Ovid) and trials registries from 1946 to 15 March 2019 with reference checking, citation searching and contact with study authors. Searches were not limited by language or publication status. We reran all searches within three months (15th March 2019) prior to publication.

SELECTION CRITERIA

Randomized controlled comparisons which included men with clinically localized prostate adenocarcinoma where hypofractionated radiation therapy (external beam radiation therapy) to the prostate using hypofractionation (greater than 2 Gy per fraction) compared with conventionally fractionated radiation therapy to the prostate delivered using standard fractionation (1.8 Gy to 2 Gy per fraction).

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology. Two authors independently assessed trial quality and extracted data. We used Review Manager 5 for data analysis and meta-analysis. We used the inverse variance method and random-effects model for data synthesis of time-to-event data with hazard ratios (HR) and 95% confidence intervals (CI) reported. For dichotomous data, we used the Mantel-Haenzel method and random-effects model to present risk ratios (RR) and 95% CI. We used GRADE to assess evidence quality for each outcome.

MAIN RESULTS

We included 10 studies with 8278 men in our analysis comparing hypofractionation with conventional fractionation to treat prostate cancer.Primary outcomesHypofractionation may result in little or no difference in prostate cancer-specific survival [PC-SS] (HR 1.00, 95% CI 0.72 to 1.39; studies = 8, participants = 7946; median follow-up 72 months; low-certainty evidence). For men in the intermediate-risk group undergoing conventional fractionation this corresponds to 976 per 1000 men alive after 6 years and 0 more (44 fewer to 18 more) alive per 1000 men undergoing hypofractionation.We are uncertain about the effect of hypofractionation on late radiation therapy gastrointestinal (GI) toxicity (RR 1.10, 95% CI 0.68 to 1.78; studies = 4, participants = 3843; very low-certainty evidence).Hypofractionation probably results in little or no difference to late radiation therapy genitourinary (GU) toxicity (RR 1.05, 95% CI 0.93 to 1.18; studies = 4, participants = 3843; moderate-certainty evidence). This corresponds to 262 per 1000 late GU radiation therapy toxicity events with conventional fractionation and 13 more (18 fewer to 47 more) per 1000 men when undergoing hypofractionation.Secondary outcomesHypofractionation results in little or no difference in overall survival (HR 0.94, 95% CI 0.83 to 1.07; 10 studies, 8243 participants; high-certainty evidence). For men in the intermediate-risk group undergoing conventional fractionation this corresponds to 869 per 1000 men alive after 6 years and 17 fewer (54 fewer to 17 more) participants alive per 1000 men when undergoing hypofractionation.Hypofractionation may result in little to no difference in metastasis-free survival (HR 1.07, 95% CI 0.65 to 1.76; 5 studies, 4985 participants; low-certainty evidence). This corresponds to 981 men per 1000 men metastasis-free at 6 years when undergoing conventional fractionation and 5 more (58 fewer to 19 more) metastasis-free per 1000 when undergoing hypofractionation.Hypofractionation likely results in a small, possibly unimportant reduction in biochemical recurrence-free survival based on Phoenix criteria (HR 0.88, 95% CI 0.68 to 1.13; studies = 5, participants = 2889; median follow-up 90 months to 108 months; moderate-certainty evidence). In men of the intermediate-risk group, this corresponds to 804 biochemical-recurrence free men per 1000 participants at six years with conventional fractionation and 42 fewer (134 fewer to 37 more) recurrence-free men per 1000 participants with hypofractionationHypofractionation likely results in little to no difference to acute GU radiation therapy toxicity (RR 1.03, 95% CI 0.95 to 1.11; 4 studies, 4174 participants at 12 to 18 weeks' follow-up; moderate-certainty evidence). This corresponds to 360 episodes of toxicity per 1000 participants with conventional fractionation and 11 more (18 fewer to 40 more) per 1000 when undergoing hypofractionation.

AUTHORS' CONCLUSIONS

These findings suggest that moderate hypofractionation (up to a fraction size of 3.4 Gy) results in similar oncologic outcomes in terms of disease-specific, metastasis-free and overall survival. There appears to be little to no increase in both acute and late toxicity.

Impact of daily soft-tissue image guidance to prostate on pelvic lymph node (PLN) irradiation for prostate patients receiving SBRT

PURPOSE

To determine the impact of using fiducial match for daily image-guidance on pelvic lymph node (PLN) coverage for prostate cancer patients receiving stereotactic body radiation therapy (SBRT).

METHODS

Thirty patients underwent SBRT treatment to the prostate and PLN from 2014 to 2016. Each patient received either 800cGy × 5 or 500cGy × 5 to the prostate and 500cGy × 5 to the PLN. A 5 mm clinical target volume (CTV)-to-planning target volume (PTV) margin around the PLN was used for planning. Two registrations with planning computed tomography (PCT) for each of the daily cone beam CTs (CBCTs) were performed: a rigid registration to fiducials and to the bony anatomy. The average translational difference between fiducial and bony match as well as percentage of fractions with differences > 5mm were calculated. Changes in bladder and rectal volume as well as center-of-mass (COM) position from simulation parameters, and their correlation with translational difference were also evaluated. The dosimetric impact of the translational differences was calculated by shifting the plan isocenter.

RESULTS

The average translational difference between fiducial and bony match was 0.06 ± 0.82, 2.1 ± 4.1, -2.8 ± 4.3, and 5.5 ± 4.2 mm for lateral, vertical, longitudinal, and vector directions. The average change in bladder and rectal volume from simulation was -67.2 ± 163.04 cc (-12 ± 52%) and -1.6 ± 18.75 (-2 ± 30%) cc. The average change in COM of bladder from the simulation position was 0.34 ± 2.49, 4.4 ± 8.1, and -3.9 ± 7.5 mm along the LR, AP, and SI directions. The corresponding COM change for the rectum was 0.17 ± 1.9, 1.34 ± 3.5, and -0.6 ± 5.2 mm.

CONCLUSIONS

The 5 mm margin covered ~75% of fractions receiving PLN irradiation with SBRT, daily CBCT and fiducial-guided setup. The dosimetric impact on PLN coverage was significant in 19% of fractions or 25% of patients. A larger translational shift was due to variation in rectal volume and changes in COM position of the bladder and rectum. A consistent bladder positioning and/or rectum filling compared with presimulation volume were essential for adequate coverage of PLN in a hypofractionated treatment regime.

Randomised Phase II Feasibility Trial of Image-guided External Beam Radiotherapy With or Without High Dose Rate Brachytherapy Boost in Men with Intermediate-risk Prostate Cancer (CCTG PR15/ NCT01982786)

AIMS

We conducted a multicentre feasibility study to assess the ability to randomise patients between image-guided radiotherapy (IGRT) and IGRT + high dose rate (HDR) brachytherapy boost and to adhere to appropriate radiation quality assurance standards.

MATERIALS AND METHODS

The primary end point was to determine the ability to randomise 60 patients over an 18 month period. Arm 1 (IGRT) patients received 78 Gy in 39 fractions or 60 Gy in 20 fractions (physician's preference), whereas arm 2 (IGRT + HDR) received 37.5 Gy in 15 fractions with HDR boost of 15 Gy. The secondary end points included >grade 3 acute genitourinary and gastrointestinal toxicity, using Common Terminology Criteria for Adverse Events version 4.0 at 3 months, validation of a prospectively defined radiation oncology quality assurance to assess treatment compliance. All analyses were descriptive; no formal comparisons between treatment arms were carried out.

RESULTS

Between April 2014 and September 2015, 57 National Comprehensive Cancer Network (NCCN)-defined intermediate-risk prostate cancer patients were randomised between IGRT alone (arm 1; n = 29) and IGRT plus HDR brachytherapy boost (arm 2; n = 28). Overall, 93% received the treatment as randomised. There were four patients (one on IGRT arm 1 and three patients on the IGRT + HDR arm 2) who were treated differently from randomisation assignment. For the 29 patients receiving IGRT (arm 1), there were 14 cases reported with minor deviations and three with major deviations. For patients on IGRT + HDR (arm 2), there were 18 cases reported with minor deviations and two with major deviations. At 3 months in the IGRT group (arm 1), one patient reported grade 3 diarrhoea, whereas in the IGRT + HDR group (arm 2), two patients reported grade 3 haematuria. No other gastrointestinal and genitourinary toxicities were reported.

CONCLUSION

The pilot study showed the feasibility of randomisation between treatment with IGRT alone versus IGRT + HDR boost. Treatment compliance was good, including adherence to quality assurance standards.

The alfa and beta of tumours: a review of parameters of the linear-quadratic model, derived from clinical radiotherapy studies

BACKGROUND

Prediction of radiobiological response is a major challenge in radiotherapy. Of several radiobiological models, the linear-quadratic (LQ) model has been best validated by experimental and clinical data. Clinically, the LQ model is mainly used to estimate equivalent radiotherapy schedules (e.g. calculate the equivalent dose in 2 Gy fractions, EQD₂), but increasingly also to predict tumour control probability (TCP) and normal tissue complication probability (NTCP) using logistic models. The selection of accurate LQ parameters α, β and α/β is pivotal for a reliable estimate of radiation response. The aim of this review is to provide an overview of published values for the LQ parameters of human tumours as a guideline for radiation oncologists and radiation researchers to select appropriate radiobiological parameter values for LQ modelling in clinical radiotherapy.

METHODS AND MATERIALS

We performed a systematic literature search and found sixty-four clinical studies reporting α, β and α/β for tumours. Tumour site, histology, stage, number of patients, type of LQ model, radiation type, TCP model, clinical endpoint and radiobiological parameter estimates were extracted. Next, we stratified by tumour site and by tumour histology. Study heterogeneity was expressed by the I² statistic, i.e. the percentage of variance in reported values not explained by chance.

RESULTS

A large heterogeneity in LQ parameters was found within and between studies (I² > 75%). For the same tumour site, differences in histology partially explain differences in the LQ parameters: epithelial tumours have higher α/β values than adenocarcinomas. For tumour sites with different histologies, such as in oesophageal cancer, the α/β estimates correlate well with histology. However, many other factors contribute to the study heterogeneity of LQ parameters, e.g. tumour stage, type of LQ model, TCP model and clinical endpoint (i.e. survival, tumour control and biochemical control).

CONCLUSIONS

The value of LQ parameters for tumours as published in clinical radiotherapy studies depends on many clinical and methodological factors. Therefore, for clinical use of the LQ model, LQ parameters for tumour should be selected carefully, based on tumour site, histology and the applied LQ model. To account for uncertainties in LQ parameter estimates, exploring a range of values is recommended.

The alfa and beta of tumours: a review of parameters of the linear-quadratic model, derived from clinical radiotherapy studies

Background

Prediction of radiobiological response is a major challenge in radiotherapy. Of several radiobiological models, the linear-quadratic (LQ) model has been best validated by experimental and clinical data. Clinically, the LQ model is mainly used to estimate equivalent radiotherapy schedules (e.g. calculate the equivalent dose in 2 Gy fractions, EQD₂), but increasingly also to predict tumour control probability (TCP) and normal tissue complication probability (NTCP) using logistic models. The selection of accurate LQ parameters α, β and α/β is pivotal for a reliable estimate of radiation response. The aim of this review is to provide an overview of published values for the LQ parameters of human tumours as a guideline for radiation oncologists and radiation researchers to select appropriate radiobiological parameter values for LQ modelling in clinical radiotherapy.

Methods and materials

We performed a systematic literature search and found sixty-four clinical studies reporting α, β and α/β for tumours. Tumour site, histology, stage, number of patients, type of LQ model, radiation type, TCP model, clinical endpoint and radiobiological parameter estimates were extracted. Next, we stratified by tumour site and by tumour histology. Study heterogeneity was expressed by the I² statistic, i.e. the percentage of variance in reported values not explained by chance.

Results

A large heterogeneity in LQ parameters was found within and between studies (I² > 75%). For the same tumour site, differences in histology partially explain differences in the LQ parameters: epithelial tumours have higher α/β values than adenocarcinomas. For tumour sites with different histologies, such as in oesophageal cancer, the α/β estimates correlate well with histology. However, many other factors contribute to the study heterogeneity of LQ parameters, e.g. tumour stage, type of LQ model, TCP model and clinical endpoint (i.e. survival, tumour control and biochemical control).

Conclusions

The value of LQ parameters for tumours as published in clinical radiotherapy studies depends on many clinical and methodological factors. Therefore, for clinical use of the LQ model, LQ parameters for tumour should be selected carefully, based on tumour site, histology and the applied LQ model. To account for uncertainties in LQ parameter estimates, exploring a range of values is recommended.

Electronic supplementary material

The online version of this article (10.1186/s13014-018-1040-z) contains supplementary material, which is available to authorized users.

Long-term outcome of a moderately hypofractionated, intensity-modulated radiotherapy approach using an endorectal balloon for patients with localized prostate cancer

BACKGROUND

Technical advances in radiotherapy delivery have simultaneously enabled dose escalation and enhanced bladder and rectal sparing. However, the optimal radiation fractionation regimen for localized prostate cancer is unclear. Laboratory and clinical evidence suggest that hypofractionation may improve the therapeutic ratio of radiotherapy. We report our institutional outcomes using moderately hypofractionated, intensity-modulated radiotherapy (IMRT), and an endorectal balloon, with emphasis on long-term biochemical control and treatment-related adverse events in patients with localized prostate cancer.

METHODS

Between January 1997 and April 2004, 596 patients with cT1-T3 prostate cancer underwent IMRT using a moderate hypofractionation regimen (76.70 Gy at 2.19 Gy/fraction) with an endorectal balloon. Using D'Amico classification, 226 (37.9%), 264 (44.3%), and 106 (17.8%) patients had low-, intermediate-, or high-risk disease, respectively. The majority of intermediate- and high-risk patients received androgen deprivation therapy. Biochemical relapse-free survival (bRFS) was evaluated using 2005 Phoenix criteria and estimated using the Kaplan-Meier method.

RESULTS

The median follow-up was 62 months. Overall 5- and 10-year bRFS rates were 92.7% and 87.7%. For low-, intermediate-, and high-risk patients, the 5-year bRFS rates were 96.9%, 93.3%, and 82.0%, respectively; the 10-year bRFS rates were 91.4%, 89.3%, and 76.2%, respectively. Prostate-specific antigen, Gleason score, and T stage were significant predictors of bRFS (all P < 0.01). The 5-year rates of severe (≥ Grade 3) adverse events were very low: 1.2% for gastrointestinal events and 1.1% for genitourinary events.

CONCLUSIONS

Long-term outcomes after moderately hypofractionated IMRT are encouraging. Moderate hypofractionation represents a safe, efficacious, alternative regimen in the treatment of localized prostate cancer.

Proton Beam Therapy Alone for Intermediate- or High-Risk Prostate Cancer: An Institutional Prospective Cohort Study

The role of proton beam therapy (PBT) as monotherapy for localized prostate cancer (PCa) remains unclear. The purpose of this study was to evaluate the efficacy and adverse events of PBT alone for these patients. Between January 2011 and July 2014, 218 patients with intermediate- and high-risk PCa who declined androgen deprivation therapy (ADT) were enrolled to the study and were treated with PBT following one of the following protocols: 74 Gray (GyE) with 37 fractions (fr) (74 GyE/37 fr), 78 GyE/39 fr, and 70 GyE/28 fr. The 5-year progression-free survival rate in the intermediate- and high-risk groups was 97% and 83%, respectively (p = 0.002). The rate of grade 2 or higher late gastrointestinal toxicity was 3.9%, and a significant increased incidence was noted in those who received the 78 GyE/39 fr protocol (p < 0.05). Grade 2 or higher acute and late genitourinary toxicities were observed in 23.5% and 3.4% of patients, respectively. Our results indicated that PBT monotherapy can be a beneficial treatment for localized PCa. Furthermore, it can preserve the quality of life of these patients. We believe that this study provides crucial hypotheses for further study and for establishing new treatment strategies.

Proceedings of the National Cancer Institute Workshop on Charged Particle Radiobiology

In April 2016, the National Cancer Institute hosted a multidisciplinary workshop to discuss the current knowledge of the radiobiological aspects of charged particles used in cancer therapy to identify gaps in that knowledge that might hinder the effective clinical use of charged particles and to propose research that could help fill those gaps. The workshop was organized into 10 topics ranging from biophysical models to clinical trials and included treatment optimization, relative biological effectiveness of tumors and normal tissues, hypofractionation with particles, combination with immunotherapy, "omics," hypoxia, and particle-induced second malignancies. Given that the most commonly used charged particle in the clinic currently is protons, much of the discussion revolved around evaluating the state of knowledge and current practice of using a relative biological effectiveness of 1.1 for protons. Discussion also included the potential advantages of heavier ions, notably carbon ions, because of their increased biological effectiveness, especially for tumors frequently considered to be radiation resistant, increased effectiveness in hypoxic cells, and potential for differentially altering immune responses. The participants identified a large number of research areas in which information is needed to inform the most effective use of charged particles in the future in clinical radiation therapy. This unique form of radiation therapy holds great promise for improving cancer treatment.

Morbidity dynamics in proton-photon or photon radiation therapy for locally advanced prostate cancer

Aim

This study evaluated the frequency and long-term dynamics of early and late post irradiation damage after proton-photon or photon therapy for locally advanced prostate cancer.

Background

The results of a randomized study of proton-photon or photon therapy using several fractionation regimes were analyzed in 272 patients with high and intermediate risk of progression.

Materials and methods

Three variants of proton boost fractionation were studied sequentially: 3.0 (8 daily fractions), 4.0 (5 fractions, 3 or 5 fractions/week), and 5.5 (3 fractions, 3 fractions/week) Gy(RBE).

Results

A significant decrease in the severity of both acute and late gastrointestinal injuries is achievable with a proton beam. The dynamics of late gastrointestinal and genitourinary toxicity over a 10-year period were generally characterized by a decrease in severity of morbidity by 30% and 15%, respectively.

Conclusions

Local irradiation with a fractional dose of 3.0-5.5 Gy(RBE) and a cumulative dose of 28.0-28.8 Gy(RBE) for protons significantly reduces the early and late rectitis severity, but does not reduce the risk of lower urinary tract injuries. Fractionation regimens do not significantly differ in toxicity levels.

[Hypofractionated irradiation of prostate cancer: What is the radiobiological understanding in 2017?]

For prostate cancer, hypofractionation has been based since 1999 on radiobiological data, which calculated a very low alpha/beta ratio (1.2 to 1.5Gy). This suggested that a better local control could be obtained, without any toxicity increase. Consequently, two types of hypofractionated schemes were proposed: "moderate" hypofractionation, with fractions of 2.5 to 4Gy, and "extreme" hypofractionation, utilizing stereotactic techniques, with fractions of 7 to 10Gy. For moderate hypofractionation, the linear-quadratic (LQ) model has been used to calculate the equivalent doses of the new protocols. The available trials have often shown a "non-inferiority", but no advantage, while the equivalent doses calculated for the hypofractionated arms were sometimes very superior to the doses of the conventional arms. This finding could suggest either an alpha/beta ratio lower than previously calculated, or a negative impact of other radiobiological parameters, which had not been taken into account. For "extreme" hypofractionation, the use of the LQ model is discussed for high dose fractions. Moreover, a number of radiobiological questions are still pending. The reduced overall irradiation time could be either a positive point (better local control) or a negative one (reduced reoxygenation). The prolonged duration of the fractions could lead to a decrease of efficacy (because allowing for reparation of sublethal lesions). Finally, the impact of the large fractions on the microenvironment and/or immunity remains discussed. The reported series appear to show encouraging short to mid-term results, but the results of randomized trials are still awaited. Today, it seems reasonable to only propose those extreme hypofractionated schemes to well-selected patients, treating small volumes with high-level stereotactic techniques.

Treatment outcomes with hypofractionated high-dose radiation therapy for prostate cancer

AIM

To report the treatment results of a retrospective cohort of prostate cancer patients treated with Hypo-RT with a high equivalent biological effective dose (BED).

BACKGROUND

Hypofractionated radiotherapy (Hypo-RT) has gained popularity and interest in the treatment of prostate cancer. However, there are few experiences with adequate follow-up reporting treatment results using high equivalent dose with Hypo-RT.

MATERIALS AND METHODS

We assigned 149 men with low-, intermediate- and high-risk prostate cancer to receive Hypo-RT with a total dose of 69 Gy/23 fractions. Late gastrointestinal (GI) and genitourinary (GU) toxicity were prospectively evaluated according to modified RTOG criteria. Biochemical no evidence of disease (bNED) was defined as the nadir prostate-specific antigen level plus 2 ng/mL.

RESULTS

The median follow-up was 53 months. For the entire cohort, the 5-year bNED rate was 94.6%, and for low-, intermediate- and high-risk patients the 5-year bNED was 100%, 96.4%, and 86% (p = 0.007), respectively. The 5-year overall survival rate was 92%. Only 1 patient died from the disease at 48 months after treatment, giving a 5-year cancer-specific survival of 98%. The worst grade ≥2 rate GI and GU toxicity was 13.4% and 14%, respectively. No grade >3 toxicity was observed. The presence of grade ≥2 GI and GU toxicity at the last follow-up was only 1.3% and 3%, respectively.

CONCLUSIONS

Hypo-RT (69 Gy/23 fractions) with a high equivalent BED produces excellent rates of biochemical control for low, intermediate and high-risk prostate cancer. The long term GU and GI toxicity rates were considered low and acceptable.

Moderate Hypofractionated Protracted Radiation Therapy and Dose Escalation for Prostate Cancer: Do Dose and Overall Treatment Time Matter?

PURPOSE

This was a retrospective study of 2 sequential dose escalation regimens of twice-weekly 4 Gy/fractions hypofractionated intensity modulated radiation therapy (IMRT): 56 Gy and 60 Gy delivered within a protracted overall treatment time (OTT) of 6.5 and 7 weeks, respectively.

METHODS AND MATERIALS

163 prostate cancer patients with cT1c-T3a disease and nodal involvement risk ≤20% (Roach index) were treated twice weekly to the prostate ± seminal vesicles with 2 sequential dose-escalated IMRT schedules: 56 Gy (14 × 4 Gy, n=81) from 2003 to 2007 and 60 Gy (15 × 4 Gy, n=82) from 2006 to 2010. Patient repositioning was made with bone matching on portal images. Gastrointestinal (GI) and genitourinary (GU) toxicities were scored according to the Common Terminology Criteria for Adverse Events version 3.0 grading scale.

RESULTS

There were no significant differences regarding the acute GU and GI toxicities in the 2 dose groups. The median follow-up times were 80.2 months (range, 4.5-121 months) and 56.5 months (range, 1.4-91.2 months) for patients treated to 56 and 60 Gy, respectively. The 5-year grade ≥2 late GU toxicity-free survivals with 56 Gy and 60 Gy were 96 ± 2.3% and 78.2 ± 5.1% (P=.001), respectively. The 5-year grade ≥2 late GI toxicity-free survivals with 56 Gy and 60 Gy were 98.6 ± 1.3% and 85.1 ± 4.5% (P=.005), respectively. Patients treated with 56 Gy showed a 5-year biochemical progression-free survival (bPFS) of 80.8 ± 4.7%, worse than patients treated with 60 Gy (93.2 ± 3.9%, P=.007). A trend for a better 5-year distant metastasis-free survival was observed among patients treated in the high-dose group (95.3 ± 2.7% vs 100%, P=.073, respectively). On multivariate analysis, only the 60-Gy group predicted for a better bPFS (P=.016, hazard ratio = 4.58).

CONCLUSIONS

A single 4-Gy additional fraction in patients treated with a hypofractionated protracted IMRT schedule of 14 × 4 Gy resulted in a similar and minimal acute toxicity, in worse moderate to severe urinary and GI late effects, but a significantly better biochemical control.

Moderate hypofractionation and simultaneous integrated boost by helical tomotherapy in prostate cancer: monoinstitutional report of acute tolerability assessment with different toxicity scales

INTRODUCTION

Based on radiobiology evidence, hypofractionated radiotherapy has the potential of improving treatment outcome in prostate cancer patients. In this study, we evaluated the safety, in terms of acutetoxicity, of using moderate hypofractionated radiotherapy delivered with Helical Tomotherapy (HT) to treat prostate cancer patients.

MATERIALS AND METHODS

Between December 2012 and April 2014, 42 consecutive patients were treated with hypofractionated radiotherapy using HT. All patients received 70 Gy in 28 fractions to PTV1, which included the prostate. In the intermediate risk group, 61.6 Gy were delivered to PTV2, which included the seminal vesicles. In high risk patients, the pelvic nodes were added (PTV3) and received 50.4 Gy. Acute toxicity was recorded prospectively with RTOG and Common Terminology Criteria for Adverse Events 3.0, retrospectively with CTCAE 4.0. Expanded Prostate Cancer Index Composite (EPIC) was measured at baseline and 3 months after end of treatment, to investigate health related quality of life with regards to bladder and gastrointestinal function.

RESULTS

Acute toxicity was acceptable, independently from the system used to score side effects. Moderate genitourinary toxicity was more frequent than gastrointestinal toxicity. No correlation between acute side effects and patients' characteristics or physical dose parameters was registered. EPIC evaluation showed a negligible difference in urinary and bowel function post-treatment, that did not reach statistical significance.

CONCLUSIONS

Our experience confirms the safety of moderate hypofractionation delivered with HT in prostate cancer patients with low, intermediate and high risk.

Prostate hypofractionated radiation therapy with injection of hyaluronic acid: acute toxicities in a phase 2 study

PURPOSE

Hypofractionated radiation therapy (RT) in prostate cancer can be developed only if the risk of rectal toxicity is controlled. In a multicenter phase 2 trial, hypofractionated irradiation was combined with an injection of hyaluronic acid (HA) to preserve the rectal wall. Tolerance of the injection and acute toxicity rates are reported.

METHODS AND MATERIALS

The study was designed to assess late grade 2 toxicity rates. The results described here correspond to the secondary objectives. Acute toxicity was defined as occurring during RT or within 3 months after RT and graded according to the Common Terminology Criteria for Adverse Events version 4.0. HA tolerance was evaluated with a visual analog scale during the injection and 30 minutes after injection and then by use of the Common Terminology Criteria at each visit.

RESULTS

From 2010 to 2012, 36 patients with low-risk to intermediate-risk prostate cancer were included. The HA injection induced a mean pain score of 4.6/10 ± 2.3. Thirty minutes after the injection, 2 patients still reported pain (2/10 and 3/10), which persisted after the intervention. Thirty-three patients experienced at least 1 acute genitourinary toxicity and 20 patients at least 1 acute gastrointestinal toxicity. Grade 2 toxicities were reported for 19 patients with urinary obstruction, frequency, or both and for 1 patient with proctitis. No grade 3 or 4 toxicities were reported. At the 3-month visit, 4 patients described grade 2 obstruction or frequency, and no patients had any grade 2 gastrointestinal toxicities.

CONCLUSIONS

The injection of HA makes it possible to deliver hypofractionated irradiation over 4 weeks with a dose per fraction of > 3 Gy, with limited acute rectal toxicity.

Prostate-specific antigen kinetics after primary stereotactic body radiation therapy using CyberKnife for localized prostate cancer

PURPOSE

To assess prostate-specific antigen (PSA) kinetics and report on the oncologic outcomes for patients with localized prostate cancer treated with stereotactic body radiation therapy (SBRT) using CyberKnife.

METHODS

We extracted the list and data of 39 patients with clinically localized prostate cancer who had undergone primary SBRT using CyberKnife between January 2008 and December 2012 from the Smart Prostate Cancer database system of Seoul St. Mary's Hospital. Changes in PSA over time, PSA velocity, and PSA nadir were evaluated from the completion of SBRT using CyberKnife. Biochemical recurrence (BCR)-free survival after primary SBRT using CyberKnife was determined using Kaplan-Meier analysis.

RESULTS

The rate of PSA decrease was maximal in the first month (median -3.34 ng/mL/mo), which then fell gradually with median values of -1.51, -0.32, -0.28, -0.20, and -0.03 ng/mL/mo for durations of 3, 6, 9, 12, and 24 months after SBRT using CyberKnife, respectively. The median PSA nadir was 0.31 ng/mL after a median 23 months. Kaplan-Meier analysis calculates an actuarial 5-year BCR-free survival after SBRT using CyberKnife as 80.8%.

CONCLUSIONS

PSA decline occurred rapidly in the first month, and then the rate of PSA decline fell off steadily over time throughout 2 years after treatment. Also, SBRT using CyberKnife leads to long-term favorable BCR-free survival in localized prostate cancer.

Hypofractionated radiotherapy for prostate cancer

In the last few years, hypofractionated external beam radiotherapy has gained increasing popularity for prostate cancer treatment, since sufficient evidence exists that prostate cancer has a low α/β ratio, lower than the one of the surrounding organs at risk and thus there is a potential therapeutic benefit of using larger fractionated single doses. Apart from the therapeutic rationale there are advantages such as saving treatment time and medical resources and thereby improving patient’s convenience. While older trials showed unsatisfactory results in both standard and hypofractionated arm due to insufficient radiation doses and non-standard contouring of target volumes, contemporary randomized studies have reported on encouraging results of tumor control mostly without an increase of relevant side effects, especially late toxicity. Aim of this review is to give a detailed analysis of relevant, recently published clinical trials with special focus on rationale for hypofractionation and different therapy settings.

Reduced radiation tolerance of penile structures associated with dose-escalated hypofractionated prostate radiotherapy

OBJECTIVE

To investigate the effect of hypofractionated external beam radiation therapy (RT) on sexual function in patients treated for localized prostate cancer, and also to determine the effect of radiation dose to the penile bulb or crura of the corpus cavernosum on sexual function outcome.

MATERIALS AND METHODS

Forty-one patients treated with hypofractionated RT without androgen deprivation were prescribed 67.6-70.2 Gy to the prostate, delivered in 26-28 fractions. The primary endpoint was erectile dysfunction (ED) category based on the Sexual Health Inventory for Men (SHIM) score closest to 2 years from RT. The penile bulb and crura were contoured and mean radiation dose calculated for each structure.

RESULTS

The mean pretreatment SHIM score was 19.8, and the mean posttreatment SHIM score was 15.1. The ED category was decreased by ≥ 2 in 50% of patients with a mean penile bulb of >20 Gy compared with that in 9% of patients with a mean penile bulb dose of ≤ 20 Gy (P = .003). Mean dose to the crura was highly correlated with mean dose to the penile bulb (Pearson correlation = 0.842; P <.001) but did not reach statistical significance as a predictor of ED after radiation.

CONCLUSION

Radiation dose to the penile bulb is predictive of posttreatment ED in patients treated with dose-escalated hypofractionated prostate RT. The cutpoint at which this effect was observed with this treatment is substantially lower than the previous reports.

Treatment outcome of localized prostate cancer by 70 Gy hypofractionated intensity-modulated radiotherapy with a customized rectal balloon

Purpose

We aimed to analyze the treatment outcome and long-term toxicity of 70 Gy hypofractionated intensity-modulated radiotherapy (IMRT) for localized prostate cancer using a customized rectal balloon.

Materials and Methods

We reviewed medical records of 86 prostate cancer patients who received curative radiotherapy between January 2004 and December 2011 at our institution. Patients were designated as low (12.8%), intermediate (20.9%), or high risk (66.3%). Thirty patients received a total dose of 70 Gy in 28 fractions over 5 weeks via IMRT (the Hypo-IMRT group); 56 received 70.2 Gy in 39 fractions over 7 weeks via 3-dimensional conformal radiotherapy (the CF-3DRT group, which served as a reference for comparison). A customized rectal balloon was placed in Hypo-IMRT group throughout the entire radiotherapy course. Androgen deprivation therapy was administered to 47 patients (Hypo-IMRT group, 17; CF-3DRT group, 30). Late genitourinary (GU) and gastrointestinal (GI) toxicity were evaluated according to the Radiation Therapy Oncology Group criteria.

Results

The median follow-up period was 74.4 months (range, 18.8 to 125.9 months). The 5-year actuarial biochemical relapse-free survival rates for low-, intermediate-, and high-risk patients were 100%, 100%, and 88.5%, respectively, for the Hypo-IMRT group and 80%, 77.8%, and 63.6%, respectively, for the CF-3DRT group (p < 0.046). No patient presented with acute or late GU toxicity ≥grade 3. Late grade 3 GI toxicity occurred in 2 patients (3.6%) in the CF-3DRT group and 1 patient (3.3%) in the Hypo-IMRT group.

Conclusion

Hypo-IMRT with a customized rectal balloon resulted in excellent biochemical control rates with minimal toxicity in localized prostate cancer patients.

Early closure of phase II prospective study on acute and late tolerance of hypofractionated radiotherapy in low-risk prostate cancer patients

AIM

To assess acute and late toxicity of hypofractionated radiotherapy, its efficacy and impact on quality of life in patients with low-risk prostate cancer.

MATERIALS AND METHODS

Since August 2006 to October 2007, 15 prostate cancer patients with favorable clinical features, aged 54-74 years (mean 67 years) entered the study. Tumor stage in the majority (73%) of patients was T2a, the mean pretreatment PSA value was 7.2 ng/ml (range 5-10.9 ng/ml). The study group was treated 3 times a week with 4 Gy per fraction to the total dose of 60 Gy within 5 weeks. 3D conformal treatment planning was used with no fiducial markers. Acute and late toxicity was evaluated using modified EORTC/RTOG/LENT scoring systems. Patients regularly filled the EORTC QLQ-PR25 questionnaires.

RESULTS

All patients completed radiotherapy according to the plan. During radiotherapy, 26% of patients had grade 1-2 rectal symptoms. The incidence of acute urinary toxicity score was 26%, 60%, and 14% for grade 0-1, 2 and 3, respectively. One year after RT, the incidence of grade 2 GI toxicity was 27%, which was the reason for an early closure of the accrual. Grade 2 late urinary toxicity was noted in 20% of patients. The mean PSA level was 0.61 ng/ml after 24 months and 0.47 ng/ml after 36 months (range: 0.06-1.54 ng/ml).

CONCLUSIONS

Low number of patients does not allow to determine the influence of hypofractionation on unsatisfactory tolerance of this regimen. Suboptimal (from the present day's perspective) target localization (no fiducial markers) could potentially explain higher than expected late GI reactions in our series.

Different rectal toxicity tolerance with and without simultaneous conventionally-fractionated pelvic lymph node treatment in patients receiving hypofractionated prostate radiotherapy

PURPOSE

To investigate added morbidity associated with the addition of pelvic elective nodal irradiation (ENI) to hypofractionated radiotherapy to the prostate.

METHODS AND MATERIALS

Two-hundred twelve patients, treated with hypofractionated radiotherapy to the prostate between 2004 and 2011, met the inclusion criteria for the analysis. All patients received 70 Gy to the prostate delivered over 28 fractions and 103 (49%) received ENI consisting of 50.4 Gy to the pelvic lymphatics delivered simultaneously in 1.8 Gy fractions. The mean dose-volume histograms were compared between the two subgroups defined by use of ENI, and various dose-volume parameters were analyzed for effect on late lower gastrointestinal (GI) and genitourinary (GU) toxicity.

RESULTS

Acute grade 2 lower GI toxicity occurred in 38 (37%) patients receiving ENI versus 19 (17%) in those who did not (p = 0.001). The Kaplan-Meier estimate of grade ≥ 2 lower GI toxicity at 3 years was 15.3% for patients receiving ENI versus 5.3% for those who did not (p = 0.026). Each rectal isodose volume was increased for patients receiving ENI up to 50 Gy (p ≤ 0.021 for each 5 Gy increment). Across all patients, the absolute V70 of the rectum was the only predictor of late GI toxicity. When subgroups, defined by the use of ENI, were analyzed separately, rectal V70 was only predictive of late GI toxicity for patients who received ENI. For patients receiving ENI, V70 > 3 cc was associated with an increased risk of late GI events.

CONCLUSIONS

Elective nodal irradiation increases the rates of acute and late GI toxicity when delivered simultaneously with hypofractioanted prostate radiotherapy. The use of ENI appears to sensitize the rectum to hot spots, therefore we recommend added caution to minimize the volume of rectum receiving 100% of the prescription dose in these patients.

Is biochemical relapse-free survival after profoundly hypofractionated radiotherapy consistent with current radiobiological models?

AIMS

The α/β ratio for prostate cancer is thought to be low and less than for the rectum, which is usually the dose-limiting organ. Hypofractionated radiotherapy should therefore improve the therapeutic ratio, increasing cure rates with less toxicity. A number of models for predicting biochemical relapse-free survival have been developed from large series of patients treated with conventional and moderately hypofractionated radiotherapy. The purpose of this study was to test these models when significant numbers of patients treated with profoundly hypofractionated radiotherapy were included.

MATERIALS AND METHODS

A systematic review of the literature with regard to hypofractionated radiotherapy for prostate cancer was conducted, focussing on data recently presented on prostate stereotactic body radiotherapy. For the work described here, we have taken published biochemical control rates for a range of moderately and profoundly fractionated schedules and plotted these together with a range of radiobiological models, which are described.

RESULTS

The data reviewed show consistency between the various radiobiological model predictions and the currently observed data.

CONCLUSION

Current radiobiological models provide accurate predictions of biochemical relapse-free survival, even when profoundly hypofractionated patients are included in the analysis.

Hypofractionated SBRT versus conventionally fractionated EBRT for prostate cancer: comparison of PSA slope and nadir

Background

Patients with early stage prostate cancer have a variety of curative radiotherapy options, including conventionally-fractionated external beam radiotherapy (CF-EBRT) and hypofractionated stereotactic body radiotherapy (SBRT). Although results of CF-EBRT are well known, the use of SBRT for prostate cancer is a more recent development, and long-term follow-up is not yet available. However, rapid post-treatment PSA decline and low PSA nadir have been linked to improved clinical outcomes. The purpose of this study was to compare the PSA kinetics between CF-EBRT and SBRT in newly diagnosed localized prostate cancer.

Materials/methods

75 patients with low to low-intermediate risk prostate cancer (T1-T2; GS 3 + 3, PSA < 20 or 3 + 4, PSA < 15) treated without hormones with CF-EBRT (>70.2 Gy, <76 Gy) to the prostate only, were identified from a prospectively collected cohort of patients treated at the University of California, San Francisco (1997–2012). Patients were excluded if they failed therapy by the Phoenix definition or had less than 1 year of follow-up or <3 PSAs. 43 patients who were treated with SBRT to the prostate to 38 Gy in 4 daily fractions also met the same criteria. PSA nadir and rate of change in PSA over time (slope) were calculated from the completion of RT to 1, 2 and 3 years post-RT.

Results

The median PSA nadir and slope for CF-EBRT was 1.00, 0.72 and 0.60 ng/ml and -0.09, -0.04, -0.02 ng/ml/month, respectively, for durations of 1, 2 and 3 years post RT. Similarly, for SBRT, the median PSA nadirs and slopes were 0.70, 0.40, 0.24 ng and -0.09, -0.06, -0.05 ng/ml/month, respectively. The PSA slope for SBRT was greater than CF-EBRT (p < 0.05) at 2 and 3 years following RT, although similar during the first year. Similarly, PSA nadir was significantly lower for SBRT when compared to EBRT for years 2 and 3 (p < 0.005).

Conclusion

Patients treated with SBRT experienced a lower PSA nadir and greater rate of decline in PSA 2 and 3 years following completion of RT than with CF-EBRT, consistent with delivery of a higher bioequivalent dose. Although follow-up for SBRT is limited, the improved PSA kinetics over CF-EBRT are promising for improved biochemical control.

Salvage therapy of small volume prostate cancer nodal failures: a review of the literature

New imaging modalities may be useful to identify prostate cancer patients with small volume, limited nodal relapse ("oligo-recurrent") potentially amenable to local treatments (radiotherapy, surgery) with the aim of long-term control of the disease, even in a condition traditionally considered prognostically unfavorable. This report reviews the new diagnostic tools and the main published data about the role of surgery and radiation therapy in this particular subgroup of patients.

La Radioterapia Nel Trattamento Del Carcinoma Della Prostata: Indicazioni, Evoluzione Tecnologica e Approcci Integrati

Prostate cancer is a heterogeneous, indolent or sometimes aggressive tumor. Treatment options are various and without proved superiority. Radiotherapy (RT) plays a key role in the disease history. Technological evolution with Intensity Modulate Radiation Therapy (IMRT) and Image Guided Radiation Therapy (IGRT) allowed improvement, with significant results on local control and survival. Hypofractionation, Stereotactic Body RT (SBRT) and new brachytherapy approachs are still under investigation, with promising opportunities. Adjuvant vs salvage postoperative RT, hormone association, prophylactic pelvic irradiation are still under debate, but guidelines express overlapping indications.

Multidisciplinary managements will be the future for care optimization, providing the best tool for holistic and informed patients' choice.

[Alpha/beta ratio revisited in the era of hypofractionation]

Large doses per fraction are not recommended in daily radiotherapy due to a higher risk of late normal tissue injury. The technical refinements of modern radiotherapy and suggestions that some tumors could be sensitive to dose per fraction have renewed the interest in hypofractionated schedules. The estimation of α/β ratio value requires large samples of carefully evaluated patients in whom total and fractional doses have varied independently. Tumor repopulation has to be considered when the treatment duration is altered. Without setting aside conflicting publication, the α/β ratio values for prostate and breast (after lumpectomy) cancers could be as low as 2.5 Gy and 4 Gy, respectively. While it is too early to change our routine protocols, the time has come to conduct clinical trials comparing different fractionation schedules.

Efficacy and toxicity of conventionally fractionated pelvic radiation with a hypofractionated simultaneous versus conventionally fractionated sequential boost for patients with high-risk prostate cancer

PURPOSE

To determine if high-risk prostate cancer responds differently to hypofractionation.

MATERIAL AND METHODS

One hundred and fifty-seven men with NCCN high-risk (T3, PSA > 20, or Gleason ≥ 8) clinically localized prostate cancer treated between 1998 and 2010 met the inclusion criteria for the analysis. Eighty-two were treated with conventional WPRT with a conventionally fractionated sequential boost to the prostate (cRT), with the prostate receiving 75-77 Gy in 1.8-2.0 Gy fractions. Seventy-five were treated with pelvic IMRT with a hypofractionated simultaneous boost to the prostate (hRT), with the prostate receiving 70 Gy in 2.5 Gy fractions. The dose to the pelvic lymph nodes was 45 Gy in the cRT group and 50.4 Gy in the hRT group, both at 1.8 Gy per fraction. Ninety-two percent received neoadjuvant hormonal ablation therapy, typically beginning two months prior to the start of RT.

RESULTS

Median follow-up was 6.5 years for men receiving cRT and 3.7 years for those receiving hRT. The actuarial rate of biochemical control at four years was 88% for cRT and 94% for hRT (p = 0.82). The rates of early rectal and urinary grade ≥ 2 toxicities were 35% (29 of 82) and 49% (40 of 82) for the cRT group and 36% (27 of 75) and 44% (33 of 75) for the hRT group. The actuarial rate of late grade ≥ 2 rectal toxicity at four years was 25% for the cRT group and 13% for the hRT group (p = 0.037). The rate of late grade 3 rectal complications was 4% (3 of 82) for patients receiving cRT and 1% (1 of 75) for patients receiving hRT.

CONCLUSION

Initial follow-up indicates equivalent biochemical control between regimens. Patients receiving hRT experienced fewer late rectal complications.

Acute toxicity profile in prostate cancer with conventional and hypofractionated treatment

Purpose

To compare the acute toxicities in radical treatment of prostate cancer between conventional schedule (C-ARM) with 78 Gy/39 fractions and hypofractionation conformal treatment (H-ARM) with 69 Gy/23 fractions.

Methods and material

This prospective double arm study consisted of 217 patients with prostate cancer, 112 in H-ARM and 105 in C-ARM arm. C-ARM received conventional six- field conformal radiotherapy with 78 Gy in 39 fractions while H-ARM received hypofractionation with 69 Gy in 23 fractions. Weekly assessment of acute reactions was done during treatment and with one, and 3 months using RTOG scale. Univariated analysis was performed to evaluate differences between the incidences of acute reaction in the treatment arms. Variables with p value less than 0.1 were included in the multivariated logistic regression.

Results

There was no difference between H-ARM versus C-ARM for severity and incidence in genitourinary (GU) and gastrointestinal (GI) acute toxicity. During the treatment comparing H-ARM with C-ARM no differences was observed for GI toxicity (grade 0–3; H-ARM = 45.5%, 34%, 18.7% and 1.8% versus C-ARM = 47.6%, 35.2%, 17.2% and 0). For acute GU toxicity no difference was detected between H-ARM (grade 0–3; 22.3%, 54.5%, 18.7% and 4.5%) and C-ARM (grade 0–3; 25.8%, 53.3%, 17.1% and 3.8%).

At the 3- months follow-up, persistent Grade > =2 acute GU and GI toxicity were 2.5% and 1.8% in H-ARM versus 5.7% and 3% in C-ARM (p > 0.05). In univariated and multivariated analyses, there was not any dosimetric predictor for GI and GU toxicity.

Conclusions

Our data demonstrate that hypofractionated radiotherapy achieving high biological effective dose using conformal radiotherapy is feasible for prostate cancer, being well tolerated with minimal severe acute toxicity.