Twice-Weekly Hypofractionated Intensity-Modulated Radiotherapy for Localized Prostate Cancer With Low-Risk Nodal Involvement: Toxicity and Outcome From a Dose Escalation Pilot Study

Association between acute histopathological changes of rectal walls and late radiation proctitis following radiotherapy for prostate cancer

PURPOSE

The impact of acute histopathological changes (HC) of the rectum on development of late clinical proctitis (LCP) after external radiotherapy (RT) for prostate cancer is poorly explored and was the primary end point of this prospective study.

METHODS

In 70 patients, 15 HC of early rectal biopsies after RT were identified, whereby RT was conventional 2D RT in 41 cases and conformational 3D RT in 29. Associations of HC in anterior and posterior rectal walls (ARW, PRW) with LCP, acute endoscopic (AEP) and acute clinical proctitis (ACP) were statistically evaluated considering as explicative variables the patient general characteristics and the HC.

RESULTS

The mean patients' follow-up was 123.5 months (24-209). The median prostatic dose was 72 Gy (2 Gy/fraction). For the 41 and 29 patients the ARW and PRW doses were 64 and 49 Gy vs. 63 and 50 Gy, respectively. The incidence of LCP ≥ grade 2 at 10 years was 12.9%. The univariate (p = 0.02) and Kaplan-Meyer methods (p = 0.007) showed that the gland (or crypts) loss in the ARW was significantly associated with LCP. AEP and ACP occurred in 14.3 and 55.7% of cases. At multivariate level AEP significantly correlated with hemorrhoids (p = 0.014) and neutrophilia in ARW (p = 0.042).

CONCLUSIONS

Early after RT, substantial gland loss in ARW is predictive of LCP. To reduce this complication with conventional fractionation, we suggest keeping the mean dose to ARW ≤48-52 Gy.

Twice- vs. thrice-weekly moderate hypofractionated radiotherapy for prostate cancer: does overall treatment time matter?

PURPOSE

To evaluate the influence of overall treatment time (OTT) in disease control, acute, and long-term side effects with moderate hypofractionated external beam radiotherapy (RT) for prostate cancer (PCa) delivered either twice- or thrice-a-week.

METHODS

157 patients with localized PCa were treated consecutively with 56 Gy in 4 Gy/fraction delivered either twice (86 patients, from 2003 to 2010, group-1) or thrice a week (71 patients, from 2010 to 2017, group-2) using IMRT or VMAT techniques. Gastrointestinal (GI) and genitourinary (GU) toxicities were scored according to the CTCAE v3.0 grading scale. Median follow-up was 110 and 56 months for groups 1 and 2, respectively.

RESULTS

At 6 weeks, patients treated thrice-a-week experienced higher acute ≥ grade-2 GU toxicity compared to those treated twice a week (25.4% vs 5.8%, p = 0.001) even though none presented ≥ grade-3 GU or GI toxicity in the thrice-a-week group. The 5-year ≥ grade-2 late GU toxicity-free survival was higher in group-1 (95.9 ± 2.3%) than in group-2 (81.5 ± 4.9%, p = 0.003), while no differences in ≥ grade-2 late GI toxicity-free survival were observed between both groups (97.5 ± 1.7% vs. 97 ± 2.1% for groups 1 and 2, respectively). The 5-year biochemical relapse-free survival (bRFS) was not different for patients treated twice compared to those treated thrice-a-week (80.6 ± 4.5% vs. 85.3 ± 4.8%, respectively, p = 0.441), as much as for patients treated in > 5 weeks vs. those treated in ≤ 5 weeks (81.3 ± 4.4% vs. 84.4 ± 5.1%, respectively, p = 0.584).

CONCLUSIONS

In this retrospective hypothesis-generating analysis, less vs. more than 5 weeks OTT may increase acute and late GU toxicities without significantly improving bRFS in patients treated to high effective doses (> 80 Gy) with moderate hypofractionated RT. Prospective trials evaluating the impact of OTT on hypofractionated schedules for PCa are warranted.

Rectal/urinary toxicity after hypofractionated vs conventional radiotherapy in low/intermediate risk localized prostate cancer: systematic review and meta analysis

Purpose

The aim of this review was to compare radiation toxicity in Localized Prostate Cancer (LPC) patients who underwent conventional fractionation (CV), hypofractionated (HYPO) or extreme hypofractionated (eHYPO) radiotherapy. We analyzed the impact of technological innovation on the management of prostate cancer, attempting to make a meta-analysis of randomized trials.

Methods

PubMed database has been explored for studies concerning acute and late urinary/gastrointestinal toxicity in low/intermediate risk LPC patients after receiving radiotherapy. Studies were then gathered into 5 groups: detected acute and chronic toxicity data from phase II non randomized trials were analyzed and Odds Ratio (OR) was calculated by comparing the number of patients with G0-1 toxicity and those with toxicity > G2 in the studied groups. A meta-analysis of prospective randomized trials was also carried out.

Results

The initial search yielded 575 results, but only 32 manuscripts met all eligibility requirements: in terms of radiation-induced side effects, such as gastrointestinal and genitourinary acute and late toxicity, hypofractionated 3DCRT seemed to be more advantageous than 3DCRT with conventional fractionation as well as IMRT with conventional fractionation compared to 3DCRT with conventional fractionation; furthermore, IMRT hypofractionated technique appeared more advantageous than IMRT with conventional fractionation in late toxicities. Randomized trials meta-analysis disclosed an advantage in terms of acute gastrointestinal and late genitourinary toxicity for Hypofractionated schemes.

Conclusions

Although our analysis pointed out a more favorable toxicity profile in terms of gastrointestinal acute side effects of conventional radiotherapy schemes compared to hypofractionated ones, prospective randomized trials are needed to better understand the real incidence of rectal and urinary toxicity in patients receiving radiotherapy for localized prostate cancer.

Rectal dose to prostate cancer patients treated with proton therapy with or without rectal spacer

The purpose of this study was to evaluate whether a spacer inserted in the prerectal space could reduce modeled rectal dose and toxicity rates for patients with prostate cancer treated in silico with pencil beam scanning (PBS) proton therapy. A total of 20 patients were included in this study who received photon therapy (12 with rectal spacer (DuraSeal™ gel) and 8 without). Two PBS treatment plans were retrospectively created for each patient using the following beam arrangements: (1) lateral-opposed (LAT) fields and (2) left and right anterior oblique (LAO/RAO) fields. Dose volume histograms (DVH) were generated for the prostate, rectum, bladder, and right and left femoral heads. The normal tissue complication probability (NTCP) for ≥grade 2 rectal toxicity was calculated using the Lyman-Kutcher-Burman model and compared between patients with and without the rectal spacer. A significantly lower mean rectal DVH was achieved in patients with rectal spacer compared to those without. For LAT plans, the mean rectal V70 with and without rectal spacer was 4.19 and 13.5%, respectively. For LAO/RAO plans, the mean rectal V70 with and without rectal spacer was 5.07 and 13.5%, respectively. No significant differences were found in any rectal dosimetric parameters between the LAT and the LAO/RAO plans generated with the rectal spacers. We found that ≥ 9 mm space resulted in a significant decrease in NTCP modeled for ≥grade 2 rectal toxicity. Rectal spacers can significantly decrease modeled rectal dose and predicted ≥grade 2 rectal toxicity in prostate cancer patients treated in silico with PBS. A minimum of 9 mm separation between the prostate and anterior rectal wall yields the largest benefit.

Impact of hydrogel spacer injections on interfraction prostate motion during prostate cancer radiotherapy

Background The dosimetric advantage of prostate-rectum spacers to displace the anterior rectal wall outside of the high-dose radiation regions has been clearly established in prostate cancer radiotherapy (RT). The aim of this study was to assess the impact of hydrogel spacer (HS) in the interfraction prostate motion in patients undergoing RT for prostate cancer. Material and methods Twenty prostate cancer patients implanted with three fiducial markers (FM) with (n = 10) or without (n = 10) HS were analyzed. Displacements between the prostate isocenter based on the FM's position and the bony anatomy were quantified in the left-right (LR), anterior-posterior (AP), superior-inferior (SI) axes by offline analyses of 122 cone beam computed tomography scans. Group systematic (M), systematic (Σ) and random (σ) setup errors were determined. Results In patients with or without HS, the overall mean interfraction prostate displacements were 0.4 versus -0.4 mm (p = 0.0001), 0.6 versus 0.6 mm (p = 0.85), and -0.6 mm versus -0.3 mm (p = 0.48) for the LR, AP, and SI axes, respectively. Prostate displacements >5 mm in the AP and SI directions were similar for both groups. No differences in M, Σ and σ setup errors were observed in the three axes between HS + or HS- patients. Conclusions HS implantation does not significantly influence the interfraction prostate motion in patients treated with RT for prostate cancer. The major expected benefit of HS is a reduction of the high-dose levels to the rectal wall without influence in prostate immobilization.

Systematic Review of the Relationship between Acute and Late Gastrointestinal Toxicity after Radiotherapy for Prostate Cancer

A small but meaningful percentage of men who are treated with external beam radiation therapy for prostate cancer will develop late gastrointestinal toxicity. While numerous strategies to prevent gastrointestinal injury have been studied, clinical trials concentrating on late toxicity have been difficult to carry out. Identification of subjects at high risk for late gastrointestinal injury could allow toxicity prevention trials to be performed using reasonable sample sizes. Acute radiation therapy toxicity has been shown to predict late toxicity in several organ systems. Late toxicities may occur as a consequential effect of acute injury. In this systematic review of published reports, we found that late gastrointestinal toxicity following prostate radiotherapy seems to be statistically and potentially causally related to acute gastrointestinal morbidity as a consequential effect. We submit that acute gastrointestinal toxicity may be used to identify at-risk patients who may benefit from additional attention for medical interventions and close follow-up to prevent late toxicity. Acute gastrointestinal toxicity could also be explored as a surrogate endpoint for late effects in prospective trials.

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.

Hypofractionated radiation therapy versus conventional radiation therapy in prostate cancer: A systematic review of its safety and efficacy

CONTEXT

New therapeutic alternatives can improve the safety and efficacy of prostate cancer treatment.

OBJECTIVES

To assess whether hypofractionated radiation therapy results in better safety and efficacy in the treatment of prostate cancer.

ACQUISITION OF EVIDENCE

Systematic review of the literature through searches on PubMed, Cochrane Library, CRD, ClinicalTrials and EuroScan, collecting indicators of safety and efficacy.

SYNTHESIS OF THE EVIDENCE

We included 2 systematic reviews and a clinical trial. In terms of efficacy, there is considerable heterogeneity among the studies, and no conclusive results were found concerning the superiority of the hypofractionated option over the normal fractionated option. In terms of safety, there were no significant differences in the onset of acute genitourinary complications between the 2 treatments. However, one of the reviews found more acute gastrointestinal complications in patients treated with hypofractionated radiation therapy. There were no significant differences in long-term complications based on the type of radiation therapy used, although the studies did have limitations.

CONCLUSIONS

To date, there are no conclusive results that show that hypofractionated radiation therapy is more effective or safer than normal fractionated radiation therapy in the treatment of localized prostate cancer.

Higher-than-expected severe (Grade 3-4) late urinary toxicity after postprostatectomy hypofractionated radiotherapy: a single-institution analysis of 1176 patients

BACKGROUND

Dose escalation and hypofractionation may have a role in postprostatectomy radiotherapy (RT), but at the risk of increasing urinary toxicity.

OBJECTIVE

To address predictors of severe (Grade ≥3) late urinary toxicities (LGUTOX3) after postoperative irradiation.

DESIGN, SETTING, AND PARTICIPANTS

A single-institution cohort of 1176 patients treated between 1993 and 2010 with adjuvant or salvage RT was analyzed. A total of 929 patients underwent conventionally fractionated (CF) RT (1.8 Gy per fraction; median dose to the prostatic bed: 70.2 Gy) with nonconformal RT (n=169), three-dimensional conformal RT (n=657), or intensity-modulated RT (n=103) technique, while 247 patients received hypofractionated helical TomoTherapy (median: 2.50 Gy per fraction) at the following doses: 117 patients at 65.8 Gy (2.35 Gy in 28 fractions), 80 patients at a median of 71.4 Gy (2.5-2.6 Gy in 28 fractions), and 50 patients at 58 Gy in 20 fractions. Total doses were converted into 2 Gy-equivalent doses (EQD2) following the linear quadratic model taking α/β=5.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Univariable and multivariable Cox regression models tested the relationship between clinicodosimetric variables and the risk of LGUTOX3 retrospectively, graded according to Common Terminology Criteria for Adverse Events v.4.0.

RESULTS AND LIMITATIONS

After a median follow-up of 98 mo, the 5-yr risk of LGUTOX3 was 6.9% and 18.1% in the CF and hypofractionated cohorts, respectively. At univariable analysis, the risk of LGUTOX3 was predicted by dose per fraction (hazard ratio [HR]: 2.96), acute Grade ≥2 toxicity (HR: 2.37), EQD2, pT4, and year of irradiation. At multivariable analyses, acute Grade ≥2 toxicity and dose per fraction independently predicted LGUTOX3 in the population, while an interaction analysis indicated a predictive role of hypertension in the hypofractionated cohort only. These findings are limited by their retrospective nature.

CONCLUSIONS

In the postprostatectomy setting, the logistic convenience of hypofractionation should be carefully balanced against the risk of severe late urinary sequelae.

PATIENT SUMMARY

This study investigated the causes of urinary adverse effects after postprostatectomy radiotherapy. Hypofractionation resulted in an increased risk of severe urinary toxicities.

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 radiotherapy in prostate cancer]

Radiotherapy plays a central role in the management of localized prostate cancer, but the total duration of treatment of nearly 2 months poses not only problems of fatigue related to repetitive transports, especially for older patients, but also increases the overall cost of treatment including linear accelerators occupancy and patient transportation. To address this problem, various teams have developed hypofractionated radiotherapy protocols seeking to maintain the same efficacy and toxicity while reducing the total duration of treatment. These hypofractionated protocols require recent techniques such as image-guided radiation therapy (IGRT) and intensity-modulated radiation therapy (IMRT). Single centre series have validated the feasibility of "light" hypofractionation schemes at doses per fraction less than 6 Gy Similarly, different teams have shown the possibility of stereotactic irradiation for delivering "severe" hypofractionation schemes at doses greater than 6 Gy per fraction. Whatever the dose per fraction, the current clinical data support the conclusion that hypofractionated radiotherapy does not increase mid-term toxicity and could even improve biochemical control. Studies with the objective of demonstrating non-inferiority are expected to definitively validate the role of hypofractionated irradiation in the treatment of prostate cancer.

Intermediate-risk prostate cancer patients treated with androgen deprivation therapy and a hypofractionated radiation regimen with or without image guided radiotherapy

BACKGROUND

To evaluate the efficacy of hypofractionated radiotherapy (HyRT) with or without image guided radiotherapy (IGRT) in intermediate risk prostate cancer.

METHODS

105 patients were treated with HyRT, 43,8 Gy and 54,75 Gy were delivered to the seminal vescicles and to the prostate, respectively; 3,65 Gy/fraction three times weekly. All patients underwent 9 months hormonal therapy. Patient position was verified with daily kV cone beam CT in 69 patients (IGRT group). Acute and late toxicities were evaluated according to RTOG scale. Biochemical relapse was defined using PSA nadir + 2 ng/mL. The data were prospectively collected and retrospectively analyzed to evaluate the efficacy of IGRT.

RESULTS

After a median follow-up of 31 months the actuarial 3-year bNED was 93,7%. During RT, 10.5% and 7.6% of patients developed ≥Grade 2 rectal and urinary toxicities, respectively. The cumulative incidence of ≥Grade 2 late rectal and urinary toxicities at 3 years were 6,9%, and 10,8%, respectively. The incidence of ≥Grade 2 late rectal toxicities was significant reduced in the IGRT group (1,6% vs. 14,5%, p=0,021). Two patients developed Grade 3 urethral obstruction and one patient developed grade 3 rectal bleeding.

CONCLUSIONS

HyRT represents a well-tolerated treatment able to achieve a high bNED. The use of daily IGRT is beneficial for reducing the incidence of late toxicities.