Conventional vs. conformal radiotherapy for prostate cancer: preliminary results of dosimetry and acute toxicity

A diagnostic approach of various urethral diseases using multimodal imaging findings: comprehensive overview

In clinical practice, urethral diseases are not as frequent as conditions affecting other components of the urinary system. Radiological imaging tests, such as retrograde urethrography, CT, MRI, and PET/CT, along with patient history, are crucial for accurately assessing relatively rare urethral lesions. This article aimed to provide a comprehensive overview of urethral lesions, from traumatic changes to neoplasms, and discuss the multimodal imaging findings of various urethral lesions that radiologists should know. To this end, the normal imaging anatomy of the urethra and a step-by-step approach that can be used in clinical practice have been presented to help in the systematic understanding of urethral lesions.

Comparative evaluation of hypofractionated radiotherapy versus conventionally fractionated radiotherapy for patients with intermediate and high risk prostate cancer

Background

The purpose of this study was to comparatively evaluate an efficacy and toxicity profile of hypofractionated radiotherapy (67.5 Gy in 25 fractions) to conventionally fractionated radiotherapy (78 Gy in 39 fractions) in prostate cancer patients with intermediate and high-risk disease.

Materials and methods

From January 2015 to December 2018, 168 patients were randomized to hypofractionated radiation treatment and conventional fractionated radiation treatment schedules of volumetric modulated arc therapy (VMAT) to the prostate and seminal vesicles. All the patients also received androgen deprivation therapy (ADT) and radiation therapy started after ADT.

Results

The median (range) follow-up was 51 (31-63) and 53 (33-64) months in the hypofractionated and conventionally fractionated regimes, respectively. The 3-year biochemical no evidence of disease (bNED) rates were 86.9% and 73.8% in the hypofractionated and conventionally fractionated groups, respectively (p = 0.032, significant). The 3-year bNED rates in patients at a high risk [i.e., pretreatment prostate-specific antigen (PSA) > 20 ng/mL, Gleason score ≥ 8, or T ≥ 2 c], were 87.9% and 73.5% (p = 0.007, significant) in the hypofractionated and conventionally fractionated radiotherapy groups, respectively. No statistically significant difference was found for late toxicity between the two groups, with 3-year grade 2 gastrointestinal toxicity rates of 19% and 16.7% and 3-year grade 2 genitourinary toxicity rates of 15.5% and 11.9% in the hypofractionated and conventionally fractionated radiotherapy groups, respectively.

Conclusion

Hypofractionated schedule is superior to the conventional fractionation schedule of radiation treatment in terms of bNED in intermediate and high grade prostate cancer patients. Also, the late toxicity is found to be equivalent between the two treatment groups.

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.

High-dose intensity-modulated radiation therapy as primary treatment of prostate cancer: genitourinary/gastrointestinal toxicity and outcomes, a single-institution experience

PURPOSE

Prostatectomy, radiotherapy and watchful waiting are the main therapeutic options available for local stage of prostate cancer (PCa). We report our experience on 394 patients affected by prostate cancer primarily treated with high-dose, image-guided, IMRT, focusing on gastrointestinal, genitourinary toxicities and biochemical control.

METHODS

From July 2003 to August 2014, 394 patients were treated with radical high-dose radiotherapy (HDRT) for prostate cancer; the mean total radiation dose was 79 Gy in standard fractions. Hormonal therapy (HT) was administered to 7.6% of low-risk patients, to 20.3% of intermediate-risk patients and to 72% of high-risk patients. Patients were evaluated for biochemical failure, local recurrence (LR) and metastases.

RESULTS

Ninety-seven patients (26.65%) developed acute GU toxicity at the medium dose of 25.4 Gy, grade 1 (G1) or grade 2 (G2) in 94 cases. Only 16 patients (4.06%) reported chronic GU toxicity (G1 or G2), and one case developed G3 cystitis. No G3 GI acute and late toxicity were detected. Fifty-six (14.2%) patients experienced LR, 26 (6.6%) developed metastases and 70 patients (17.8%) were deceased. Gleason sum score > 7 was predictive for worse overall survival (GS = 7 was borderline) and for metastasis. No factors resulted predictive for local relapse. HT pre-RT had been demonstrated as a negative predictor for OS and DFS-DM.

CONCLUSIONS

Data confirm the safety of HDRT for PCa. Treatment was efficient with low toxicity profile. Moreover, continued technologic advancements, as image-guided radiotherapy, could lead to further reduction in toxicity, thus increasing the therapeutic index.

Clinical and radiobiological evaluation of a method for planning target volume generation dependent on organ-at-risk exclusions in magnetic resonance imaging-based prostate radiotherapy

Background and purpose

Due to a smaller target volume when delineating prostate on magnetic resonance imaging (MRI), margins may be too tight as compared to computed tomography (CT) delineation, potentially reducing tumor control probability (TCP) in prostate radiotherapy. This study evaluated a clinically implemented MRI-based target expansion method to provide adequate margins yet limit organ-at-risk (OAR) dose as compared to CT-based delineation.

Methods and materials

Patients in this study were treated to 79.2 Gy in 44 fractions via intensity modulated radiotherapy using an MRI-based expansion method, which excluded OARs when performing a 5 mm isotropic (except 4 mm posterior) expansion from gross tumor volume to clinical target volume (CTV), followed by an isotropic 5 mm expansion to generate the planning target volume (PTV). Ten cases were re-planned using CT-delineated prostate with CTV-to-PTV expansion of isotropic 8 mm, except for a 5 mm posterior expansion, with comparison of PTV volumes, TCP and normal tissue complication probability (NTCP) to the MRI-based method. Under IRB approved protocol, we retrospectively evaluated 51 patients treated with the MRI-based method for acute bladder and rectal toxicity with CTC-AE version 4.0 used for scoring.

Results

MRI-based PTV volume differed by 4% compared to CT-based PTV volume. Radiobiological calculated TCP of the MRI-based method was found comparable to CT-based methods with an average equivalent uniform dose of 80.5 Gy and 80.1 Gy respectively. Statistically significant decrease in bladder NTCP (toxicity Grade 2 and above for 5% complications within 5 years post radiotherapy) was observed in the MRI-based method. Outcomes data collected showed 65% and 100% of patients studied experienced Grade 0/1 bladder and rectal acute toxicity respectively. Grade 2 bladder toxicity was indicated in the remaining 35% of patients studied with no Grade 3 toxicity reported.

Conclusions

Results showed comparable PTV volume with MRI-based method, and NTCP was reduced while maintaining TCP. Clinically, bladder and rectal toxicities were observed to be minimal.

Innovations in Three-Dimensional Treatment Planning and Quality Assurance

Radiation therapy treatment planning and treatment delivery are in the process of changing dramatically over the next several years. This change has been driven in large part by continued advances in computer hardware and software and in medical imaging. Three-dimensional radiation treatment planning systems are rapidly being implemented in clinics around the world. These developments in turn have prompted manufacturers to employ advanced microcircuitry and computer technology to produce treatment delivery systems capable of precise shaping of dose distributions via computer-controlled multileaf collimators which cause the beam intensity to be varied across the beam. Image-based 3D planning and beam intensity modulated delivery systems show significant potential for improving the quality of radiotherapy and improving the efficiency with which radiation therapy can be planned and delivered. However, significant research and development work on these systems and their clinical use remains to be performed. The techniques used for the treatment planning and the methods used for quality assurance procedures and testing must all be revised and/or redesigned to allow efficient clinical use of these technological advances. Although much of the current 3D radiation therapy process requires interactive tasks (and some still very laborious) the path is clear toward solving the technological obstacles so that a nearly automated planning, delivery, and verification system will become a reality over the next decade. Such systems will allow radiation oncologists to significantly increase dose to many tumor sites while concomitantly lowering doses to critical organs-at-risk. Most of the tasks will be automated, thus lowering the overall costs currently needed to provide high-quality external beam radiation therapy.

Incidence and Dose-volume Analysis of Acute Bladder Toxicity following Pelvic Radiotherapy

Aims and Background

The authors performed this prospective study to evaluate the incidence of acute bladder toxicity following pelvic radiation therapy and to determine any dosimetric predictors for the toxicity.

Methods and Study Design

Acute bladder toxicity was evaluated weekly by physicians using the Common Terminology Criteria for Adverse Events (CTCAE version 4.0). At the same time, the International Prostate Symptom Score (IPSS) and Overactive Bladder Symptom Score (OABSS) were also assessed by each patient during radiation therapy. We contoured the bladder wall, solid bladder and trigone on the planning computed tomography and analyzed dose-volume histograms to determine which of these could be the most suitable dosimetric predictor.

Results

Of 92 eligible patients, 27 (29%) demonstrated CTCAE grade 2 acute bladder toxicity, with nocturia as the most frequently observed symptom. IPSS demonstrated better agreement with CTCAE than OABSS. In receiver-operating characteristic curve analysis, the largest area under the curve was observed for V20 of both the bladder wall and the bladder.

Conclusions

Acute bladder toxicity during pelvic radiation therapy is not a trivial complication and should be actively investigated. Dose-volume relationships demonstrate that both bladder wall V20 and bladder solid V20 are useful surrogates for identifying patients at high risk of toxicity. The roles of IPSS and OABSS need to be validated in a larger study.

Interventions to reduce acute and late adverse gastrointestinal effects of pelvic radiotherapy for primary pelvic cancers

BACKGROUND

An increasing number of people survive cancer but a significant proportion have gastrointestinal side effects as a result of radiotherapy (RT), which impairs their quality of life (QoL).

OBJECTIVES

To determine which prophylactic interventions reduce the incidence, severity or both of adverse gastrointestinal effects among adults receiving radiotherapy to treat primary pelvic cancers.

SEARCH METHODS

We conducted searches of CENTRAL, MEDLINE, and Embase in September 2016 and updated them on 2 November 2017. We also searched clinical trial registries.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) of interventions to prevent adverse gastrointestinal effects of pelvic radiotherapy among adults receiving radiotherapy to treat primary pelvic cancers, including radiotherapy techniques, other aspects of radiotherapy delivery, pharmacological interventions and non-pharmacological interventions. Studies needed a sample size of 20 or more participants and needed to evaluate gastrointestinal toxicity outcomes. We excluded studies that evaluated dosimetric parameters only. We also excluded trials of interventions to treat acute gastrointestinal symptoms, trials of altered fractionation and dose escalation schedules, and trials of pre- versus postoperative radiotherapy regimens, to restrict the vast scope of the review.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology. We used the random-effects statistical model for all meta-analyses, and the GRADE system to rate the certainty of the evidence.

MAIN RESULTS

We included 92 RCTs involving more than 10,000 men and women undergoing pelvic radiotherapy. Trials involved 44 different interventions, including radiotherapy techniques (11 trials, 4 interventions/comparisons), other aspects of radiotherapy delivery (14 trials, 10 interventions), pharmacological interventions (38 trials, 16 interventions), and non-pharmacological interventions (29 trials, 13 interventions). Most studies (79/92) had design limitations. Thirteen studies had a low risk of bias, 50 studies had an unclear risk of bias and 29 studies had a high risk of bias. Main findings include the following:Radiotherapy techniques: Intensity-modulated radiotherapy (IMRT) versus 3D conformal RT (3DCRT) may reduce acute (risk ratio (RR) 0.48, 95% confidence interval (CI) 0.26 to 0.88; participants = 444; studies = 4; I2 = 77%; low-certainty evidence) and late gastrointestinal (GI) toxicity grade 2+ (RR 0.37, 95% CI 0.21 to 0.65; participants = 332; studies = 2; I2 = 0%; low-certainty evidence). Conformal RT (3DCRT or IMRT) versus conventional RT reduces acute GI toxicity grade 2+ (RR 0.57, 95% CI 0.40 to 0.82; participants = 307; studies = 2; I2 = 0%; high-certainty evidence) and probably leads to less late GI toxicity grade 2+ (RR 0.49, 95% CI 0.22 to 1.09; participants = 517; studies = 3; I2 = 44%; moderate-certainty evidence). When brachytherapy (BT) is used instead of external beam radiotherapy (EBRT) in early endometrial cancer, evidence indicates that it reduces acute GI toxicity (grade 2+) (RR 0.02, 95% CI 0.00 to 0.18; participants = 423; studies = 1; high-certainty evidence).Other aspects of radiotherapy delivery: There is probably little or no difference in acute GI toxicity grade 2+ with reduced radiation dose volume (RR 1.21, 95% CI 0.81 to 1.81; participants = 211; studies = 1; moderate-certainty evidence) and maybe no difference in late GI toxicity grade 2+ (RR 1.02, 95% CI 0.15 to 6.97; participants = 107; studies = 1; low-certainty evidence). Evening delivery of RT may reduce acute GI toxicity (diarrhoea) grade 2+ during RT compared with morning delivery of RT (RR 0.51, 95% CI 0.34 to 0.76; participants = 294; studies = 2; I2 = 0%; low-certainty evidence). There may be no difference in acute (RR 2.22, 95% CI 0.62 to 7.93, participants = 110; studies = 1) and late GI toxicity grade 2+ (RR 0.44, 95% CI 0.12 to 1.65; participants = 81; studies = 1) between a bladder volume preparation of 1080 mls and that of 540 mls (low-certainty evidence). Low-certainty evidence on balloon and hydrogel spacers suggests that these interventions for prostate cancer RT may make little or no difference to GI outcomes.Pharmacological interventions: Evidence for any beneficial effects of aminosalicylates, sucralfate, amifostine, corticosteroid enemas, bile acid sequestrants, famotidine and selenium is of a low or very low certainty. However, evidence on certain aminosalicylates (mesalazine, olsalazine), misoprostol suppositories, oral magnesium oxide and octreotide injections suggests that these agents may worsen GI symptoms, such as diarrhoea or rectal bleeding.Non-pharmacological interventions: Low-certainty evidence suggests that protein supplements (RR 0.23, 95% CI 0.07 to 0.74; participants = 74; studies = 1), dietary counselling (RR 0.04, 95% CI 0.00 to 0.60; participants = 74; studies = 1) and probiotics (RR 0.43, 95% CI 0.22 to 0.82; participants = 923; studies = 5; I2 = 91%) may reduce acute RT-related diarrhoea (grade 2+). Dietary counselling may also reduce diarrhoeal symptoms in the long term (at five years, RR 0.05, 95% CI 0.00 to 0.78; participants = 61; studies = 1). Low-certainty evidence from one study (108 participants) suggests that a high-fibre diet may have a beneficial effect on GI symptoms (mean difference (MD) 6.10, 95% CI 1.71 to 10.49) and quality of life (MD 20.50, 95% CI 9.97 to 31.03) at one year. High-certainty evidence indicates that glutamine supplements do not prevent RT-induced diarrhoea. Evidence on various other non-pharmacological interventions, such as green tea tablets, is lacking.Quality of life was rarely and inconsistently reported across included studies, and the available data were seldom adequate for meta-analysis.

AUTHORS' CONCLUSIONS

Conformal radiotherapy techniques are an improvement on older radiotherapy techniques. IMRT may be better than 3DCRT in terms of GI toxicity, but the evidence to support this is uncertain. There is no high-quality evidence to support the use of any other prophylactic intervention evaluated. However, evidence on some potential interventions shows that they probably have no role to play in reducing RT-related GI toxicity. More RCTs are needed for interventions with limited evidence suggesting potential benefits.

A treatment planning study comparing tomotherapy, volumetric modulated arc therapy, Sliding Window and proton therapy for low-risk prostate carcinoma

BACKGROUND

Comparing radiation treatment plans to ascertain the optimal intensity-modulated radiation technique for low-risk prostate cancer.

METHODS

Treatment plans for 20 randomly selected patients were generated using the same dose objectives. A dosimetric comparison was performed between various intensity-modulated techniques, including protons. All treatment plans provided conventional treatment with 79.2Gy. Dosimetric indices for the target volume and organs at risk (OAR), including homogeneity index and four conformity indices were analyzed.

RESULTS

No statistically significant differences between techniques were observed for homogeneity values. Dose distributions showed significant differences at low-to-medium doses. At doses above 50Gy all techniques revealed a steep dose gradient outside the planning target volume (PTV). Protons demonstrated superior rectum sparing at low-to-higher doses (V10-V70, P < .05) and bladder sparing at low-to-medium doses (V10-V30, P < .05). Helical tomotherapy (HT) provided superior rectum sparing compared to Sliding Window (SW) and Rapid Arc (RA) (V10-V70, P < .05). SW displayed superior bladder sparing compared to HT and RA (V10-V50, P < .05). Protons generated significantly higher femoral heads exposure and HT had superior sparing of those.

CONCLUSION

All techniques are able to provide a homogeneous and highly conformal dose distribution. Protons demonstrated superior sparing of the rectum and bladder at a wide dose spectrum. The radiation technique itself as well as treatment planning algorithms result in different OAR sparing between HT, SW and RA, with superior rectum sparing by HT and superior bladder sparing by SW. Radiation plans can be further optimized by individual modification of dose objectives dependent on treatment plan strategy.

Saw Palmetto for Symptom Management During Radiation Therapy for Prostate Cancer

CONTEXT

Lower urinary tract symptoms (LUTSs) affect 75%-80% of men undergoing radiation therapy (RT) for prostate cancer.

OBJECTIVES

To determine the safety, maximum tolerated dose (MTD), and preliminary efficacy of Serenoa repens commonly known as saw palmetto (SP) for management of LUTS during RT for prostate cancer.

METHODS

The dose finding phase used the time-to-event continual reassessment method to evaluate safety of three doses (320, 640, and 960 mg) of SP. Dose-limiting toxicities were assessed for 22 weeks using the Common Terminology Criteria for Adverse Events for nausea, gastritis, and anorexia. The exploratory randomized controlled trial phase assessed preliminary efficacy of the MTD against placebo. The primary outcome of LUTS was measured over 22 weeks using the International Prostate Symptom Score. Additional longitudinal assessments included quality of life measured with the Functional Assessment of Cancer Therapy-Prostate.

RESULTS

The dose finding phase was completed by 27 men who reported no dose-limiting toxicities and with 20 participants at the MTD of 960 mg daily. The exploratory randomized controlled trial phase included 21 men, and no statistically significant differences in the International Prostate Symptom Score were observed. The prostate-specific concerns score of the Functional Assessment of Cancer Therapy-Prostate improved in the SP group (P = 0.03). Of 11 men in the placebo group, two received physician-prescribed medications to manage LUTS compared with none of the 10 men in the SP group.

CONCLUSION

SP at 960 mg may be a safe herbal supplement, but its efficacy in managing LUTS during RT needs further investigation.

Comparison of hybrid volumetric modulated arc therapy (VMAT) technique and double arc VMAT technique in the treatment of prostate cancer

BACKGROUND

Volumetric modulated arc therapy (VMAT) has quickly become accepted as standard of care for the treatment of prostate cancer based on studies showing it is able to provide faster delivery with adequate target coverage and reduced monitor units while maintaining organ at risk (OAR) sparing. This study aims to demonstrate the potential to increase dose conformality with increased planner control and OAR sparing using a hybrid treatment technique compared to VMAT.

METHODS

Eleven patients having been previously treated for prostate cancer with VMAT techniques were replanned with a hybrid technique on Varian Treatment Planning System. Multiple static IMRT fields (2 to 3) were planned initially based on critical OAR to reduce dose but provide some planning treatment volume (PTV) coverage. This was used as a base dose plan to provide 30-35% coverage for a single arc VMAT plan.

RESULTS

The clinical VMAT plan was used as a control for the purposes of comparison. Average of all OAR sparing between the hybrid technique and VMAT showed the hybrid plan delivering less dose in almost all cases except for V80 of the bladder and maximum dose to right femoral head. PTV coverage was superior with the VMAT technique. Monitor unit differences varied, with the hybrid plan able to deliver fewer units 37% of the time, similar results 18% of the time, and higher units 45% of the time. On average, the hybrid plan delivered 10% more monitor units.

CONCLUSIONS

The hybrid plan can be delivered in a single gantry rotation combining aspects of VMAT with regions of dynamic intensity modulated radiation therapy (IMRT) within the treatment arc.

Efficacy and toxicity of external-beam radiation therapy for localised prostate cancer: a network meta-analysis

BACKGROUND

Many radiation regimens for treating prostate cancer have been used over the years, but which regimen is optimal for localised or locally advanced prostate cancer lacks consensus. We performed a network meta-analysis to identify the optimal radiation regimen.

METHODS

We systematically reviewed data from 27 randomised controlled trials and could group seven radiation regimens as follows: low- and high-dose radiation therapy (LDRT and HDRT), LDRT+ short- or long-term androgen deprivation therapy (LDRT+SADT and LDRT+LADT), HDRT+SADT, hypofractionated radiotherapy (HFRT), and HFRT+SADT. The main outcomes were overall mortality (OM), prostate-specific antigen (PSA) failure, cancer-specific mortality, and adverse events.

RESULTS

For the network meta-analysis of 27 trials, LDRT+LADT and LDRT+SADT were associated with decreased risk of OM as compared with LDRT alone as was LDRT+LADT compared with HDRT. Apart from HFRT, all other treatments were associated with decreased risk of PSA failure as compared with LDRT. HFRT+SADT was associated with decreased risk of cancer-specific mortality as compared with HFRT, LDRT+SADT, HDRT, and LDRT.

CONCLUSIONS

HFRT+SADT therapy might be the most efficacious treatment but with worst toxicity for localised or locally advanced prostate cancer, and HDRT showed excellent efficacy but more adverse events.

Escalated-dose versus control-dose conformal radiotherapy for prostate cancer: long-term results from the MRC RT01 randomised controlled trial

BACKGROUND

The aim of this trial was to compare dose-escalated conformal radiotherapy with control-dose conformal radiotherapy in patients with localised prostate cancer. Preliminary findings reported after 5 years of follow-up showed that escalated-dose conformal radiotherapy improved biochemical progression-free survival. Based on the sample size calculation, we planned to analyse overall survival when 190 deaths occurred; this target has now been reached, after a median 10 years of follow-up.

METHODS

RT01 was a phase 3, open-label, international, randomised controlled trial enrolling men with histologically confirmed T1b-T3a, N0, M0 prostate cancer with prostate specific antigen of less than 50 ng/mL. Patients were randomly assigned centrally in a 1:1 ratio, using a computer-based minimisation algorithm stratifying by risk of seminal vesicle invasion and centre to either the control group (64 Gy in 32 fractions, the standard dose at the time the trial was designed) or the escalated-dose group (74 Gy in 37 fractions). Neither patients nor investigators were masked to assignment. All patients received neoadjuvant androgen deprivation therapy for 3-6 months before the start of conformal radiotherapy, which continued until the end of conformal radiotherapy. The coprimary outcome measures were biochemical progression-free survival and overall survival. All analyses were done on an intention-to-treat basis. Treatment-related side-effects have been reported previously. This trial is registered, number ISRCTN47772397.

FINDINGS

Between Jan 7, 1998, and Dec 20, 2001, 862 men were registered and 843 subsequently randomly assigned: 422 to the escalated-dose group and 421 to the control group. As of Aug 2, 2011, 236 deaths had occurred: 118 in each group. Median follow-up was 10·0 years (IQR 9·1-10·8). Overall survival at 10 years was 71% (95% CI 66-75) in each group (hazard ratio [HR] 0·99, 95% CI 0·77-1·28; p=0·96). Biochemical progression or progressive disease occurred in 391 patients (221 [57%] in the control group and 170 [43%] in the escalated-dose group). At 10 years, biochemical progression-free survival was 43% (95% CI 38-48) in the control group and 55% (50-61) in the escalated-dose group (HR 0·69, 95% CI 0·56-0·84; p=0·0003).

INTERPRETATION

At a median follow-up of 10 years, escalated-dose conformal radiotherapy with neoadjuvant androgen deprivation therapy showed an advantage in biochemical progression-free survival, but this advantage did not translate into an improvement in overall survival. These efficacy data for escalated-dose treatment must be weighed against the increase in acute and late toxicities associated with the escalated dose and emphasise the importance of use of appropriate modern radiotherapy methods to reduce side-effects.

FUNDING

UK Medical Research Council.

Radiosensitization in prostate cancer: mechanisms and targets

Prostate cancer is the second most commonly diagnosed cancer in American men over the age of 45 years and is the third most common cause of cancer related deaths in American men. In 2012 it is estimated that 241,740 men will be diagnosed with prostate cancer and 28,170 men will succumb to prostate cancer. Currently, radiation therapy is one of the most common definitive treatment options for localized prostate cancer. However, significant number of patients undergoing radiation therapy will develop locally persistent/recurrent tumours. The varying response rates to radiation may be due to 1) tumor microenvironment, 2) tumor stage/grade, 3) modality used to deliver radiation, and 4) dose of radiation. Higher doses of radiation has not always proved to be effective and have been associated with increased morbidity. Compounds designed to enhance the killing effects of radiation, radiosensitizers, have been extensively investigated over the past decade. The development of radiosensitizing agents could improve survival, improve quality of life and reduce costs, thus benefiting both patients and healthcare systems. Herin, we shall review the role and mechanisms of various agents that can sensitize tumours, specifically prostate cancer.

Comparison of three-dimensional conformal irradiation techniques for prostate cancer using a low-energy (6 MV) photon beam

Purpose: To evaluate composite coplanar and non-coplanar three-dimensional conformal techniques (3D-CRT) for external-beam prostate radiotherapy using a low-energy (6 MV) photon beam.

Methods and Materials: For treatment-planning purposes, three different planning target volumes (PTV) were defined for ten patients with prostate cancer and as follows: PTV1 (pelvis), PTV2 (prostate + seminal vesicles + 1 cm margin) and PTV3 (prostate + 1 cm margin). Conformal techniques of 2, 3, 4, 5 (coplanar) and 6 (non-coplanar) field techniques have been considered and combined to produce five different plan combinations (i.e. techniques A, B, C, D and E). Treatment plans were generated with a prescription dose of 75 Gy to PTV3, 65 Gy to PTV2 and 45 Gy to PTV1 and were assessed on the basis of 3D dose distributions and dose-volume histograms (DVHs). Normal tissue-dose constraints for the relevant organs at risk (OARs), that is, rectum, bladder and femoral heads, were also considered.

Results: Findings show that all five treatment-plan combinations result in adequate PTV coverage and acceptable OAR irradiated volumes. The greatest rectal spacing in the high-dose region is achieved by technique C; all techniques achieve this, except for technique A, and give approximately the same fraction of volume (of rectum) that receives a dose of 50 Gy (V50) and 60 Gy (V60). When considering the bladder, techniques B, D and E give the best bladder sparing with small absolute differences, whereas technique A results in the lowest dose for femoral heads. Technique E appears to give the best compromise for all three considered OARs, provided the PTV is adequately covered.

Conclusions: Even though the optimum photon-beam energy for conformal prostate radiotherapy is greater than 10 MV, our study shows that a good sparing of OAR can be achieved even with a lower-energy beam (6 MV) and the appropriate plan combination and that the dose to prostate can be as high as 75 Gy.

Comparison of acute and late toxicities for three modern high-dose radiation treatment techniques for localized prostate cancer

PURPOSE

We compared acute and late genitourinary (GU) and gastrointestinal (GI) toxicities in prostate cancer patients treated with three different high-dose radiation techniques.

METHODS AND MATERIALS

A total of 1,903 patients with localized prostate cancer were treated with definitive RT at William Beaumont Hospital from 1992 to 2006: 22% with brachytherapy alone (BT), 55% with image-guided external beam (EB-IGRT), and 23% external beam with high-dose-rate brachytherapy boost (EBRT+HDR). Median dose with BT was 120 Gy for LDR and 38 Gy for HDR (9.5 Gy × 4). Median dose with EB-IGRT was 75.6 Gy (PTV) to prostate with or without seminal vesicles. For EBRT+HDR, the pelvis was treated to 46 Gy with an additional 19 Gy (9.5 Gy × 2) delivered via HDR. GI and GU toxicity was evaluated utilizing the NCI-CTC criteria (v.3.0). Median follow-up was 4.8 years.

RESULTS

The incidences of any acute ≥ Grade 2 GI or GU toxicities were 35%, 49%, and 55% for BT, EB-IGRT, and EBRT+HDR (p < 0.001). Any late GU toxicities ≥ Grade 2 were present in 22%, 21%, and 28% for BT, EB-IGRT, and EBRT+HDR (p = 0.01), respectively. Patients receiving EBRT+HDR had a higher incidence of urethral stricture and retention, whereas dysuria was most common in patients receiving BT. Any Grade ≥ 2 late GI toxicities were 2%, 20%, and 9% for BT, EB-IGRT, and EBRT+HDR (p < 0.001). Differences were most pronounced for rectal bleeding, with 3-year rates of 0.9%, 20%, and 6% (p < 0.001) for BT, EB-IGRT, and EBRT+HDR respectively.

CONCLUSIONS

Each of the three modern high-dose radiation techniques for localized prostate cancer offers a different toxicity profile. These data can help patients and physicians to make informed decisions regarding radiotherapy for prostate andenocarcinoma.

Three-dimensional conformal radiation therapy for esophageal squamous cell carcinoma: is elective nodal irradiation necessary?

PURPOSE

To evaluate the local control, survival, and toxicity associated with three-dimensional conformal radiotherapy (3D-CRT) for squamous cell carcinoma (SCC) of the esophagus, to determine the appropriate target volumes, and to determine whether elective nodal irradiation is necessary in these patients.

METHODS AND MATERIALS

A prospective study of 3D-CRT was undertaken in patients with esophageal SCC without distant metastases. Patients received 68.4 Gy in 41 fractions over 44 days using late-course accelerated hyperfractionated 3D-CRT. Only the primary tumor and positive lymph nodes were irradiated. Isolated out-of-field regional nodal recurrence was defined as a recurrence in an initially uninvolved regional lymph node.

RESULTS

All 53 patients who made up the study population tolerated the irradiation well. No acute or late Grade 4 or 5 toxicity was observed. The median survival time was 30 months (95% confidence interval, 17.7-41.8). The overall survival rate at 1, 2, and 3 years was 77%, 56%, and 41%, respectively. The local control rate at 1, 2, and 3 years was 83%, 74%, and 62%, respectively. Thirty-nine of the 53 patients (74%) showed treatment failure. Seventeen of the 39 (44%) developed an in-field recurrence, 18 (46%) distant metastasis with or without regional failure, and 3 (8%) an isolated out-of-field nodal recurrence only. One patient died of disease in an unknown location.

CONCLUSIONS

In patients treated with 3D-CRT for esophageal SCC, the omission of elective nodal irradiation was not associated with a significant amount of failure in lymph node regions not included in the planning target volume. Local failure and distant metastases remained the predominant problems.

Acute toxicity of image-guided hypofractionated radiotherapy for prostate cancer: nonrandomized comparison with conventional fractionation

OBJECTIVES

To compare acute toxicity of prostate cancer image-guided hypofractionated radiotherapy (hypo-IGRT) with conventional fractionation without image-guidance (non-IGRT). To test the hypothesis that the potentially injurious effect of hypofractionation can be counterbalanced by the reduced irradiated normal tissue volume using IGRT approach.

MATERIALS AND METHODS

One hundred seventy-nine cT1-T2N0M0 prostate cancer patients were treated within the prospective study with 70.2 Gy/26 fractions (equivalent to 84 Gy/42 fractions, α/β 1.5 Gy) using IGRT (transabdominal ultrasound, ExacTrac X-Ray system, or cone-beam computer tomography). Their prospectively collected data were compared with data of 174 patients treated to 80 Gy/40 fractions with non-IGRT. The difference between hypo-IGRT and non-IGRT cohorts included fractionation (hypofractionation vs. conventional fractionation), margins (hypo-IGRT margins: 7 mm and 3 mm, for all but posterior margins; respectively; non-IGRT margins: 10 and 5 mm, for all but posterior margins, respectively), and use of image-guidance or not. Multivariate analysis was performed to define the tumor-, patient-, and treatment-related predictors for acute toxicity.

RESULTS

All patients completed the prescribed radiotherapy course. Acute toxicity in the hypo-IGRT cohort included rectal (G1: 29.1%; G2: 11.2%; G3: 1.1%) and urinary events (G1: 33.5%; G2: 39.1%; G3: 5%). Acute toxicity in the non-IGRT patients included rectal (G1: 16.1%; G2: 6.3%) and urinary events (G1: 36.2%; G2: 20.7%; G3: 0.6%). In 1 hypo-IGRT and 2 non-IGRT patients, radiotherapy was temporarily interrupted due to acute toxicity. The incidence of mild (G1-2) rectal and bladder complications was significantly higher for hypo-IGRT (P = 0.0014 and P < 0.0001, respectively). Multivariate analysis showed that hypo-IGRT (P = 0.001) and higher PSA (P = 0.046) are correlated with higher acute urinary toxicity. No independent factor was identified for acute rectal toxicity. No significant impact of IGRT system on acute toxicity was observed.

CONCLUSIONS

The acute toxicity rates were low and similar in both study groups with some increase in mild acute urinary injury in the hypo-IGRT patients (most probably due to the under-reporting in the retrospectively analyzed non-IGRT cohort). The higher incidence of acute bowel reactions observed in hypo-IGRT group was not significant in the multivariate analysis. Further investigation is warranted in order to exclude the bias due to the nonrandomized character of the study.

Positional reproducibility and effects of a rectal balloon in prostate cancer radiotherapy

Despite the increasing use of the rectal balloon in prostate cancer radiotherapy, many issues still remain to be verified objectively including its positional reproducibility and relevance to treatment morbidity. We have developed a custom rectal balloon that has a scale indicating the depth of insertion and dilates symmetrically ensuring positional reproducibility. Fifty patients with prostate cancer treated by definitive 3D-conformal radiotherapy (3D-CRT) or intensity-modulated radiotherapy (IMRT) with rectal balloon were analyzed. Each of first five patients undergone computed tomography (CT) three times with a rectal balloon. The positional reproducibility was tested by Intraclass Correlation Coefficient (ICC) from the CT-to-CT fusion images. Planning variables and clinical acute toxicities were compared between when or not applying balloon. An ICC of greater than 0.9 in all directions revealed an excellent reproducibility of the balloon. Rectal balloon improved considerably the mean dose and V(45Gy)-V(65Gy) in plan comparison, and especially in 3D-CRT the rectal volume exposed to more than 60 Gy dropped from 41.3% to 19.5%. Clinically, the balloon lowered acute toxicity, which was lowest when both the balloon and IMRT were applied simultaneously. The rectal balloon carries excellent reproducibility and reduces acute toxicity in 3D-CRT and IMRT for prostate cancer.

Molecular fingerprinting of radiation resistant tumors: can we apprehend and rehabilitate the suspects?

Radiation therapy continues to be one of the more popular treatment options for localized prostate cancer. One major obstacle to radiation therapy is that there is a limit to the amount of radiation that can be safely delivered to the target organ. Emerging evidence suggests that therapeutic agents targeting specific molecules might be combined with radiation therapy for more effective treatment of tumors. Recent studies suggest that modulation of these molecules by a variety of mechanisms (e.g., gene therapy, antisense oligonucleotides, small interfering RNA) may enhance the efficacy of radiation therapy by modifying the activity of key cell proliferation and survival pathways such as those controlled by Bcl-2, p53, Akt/PTEN and cyclooxygenase-2. In this article, we summarize the findings of recent investigations of radiosensitizing agents in the treatment of prostate cancer.

Análise comparativa dos histogramas de dose e volume entre planejamentos tridimensionais conformados e convencionais não conformados na radioterapia do câncer de próstata

OBJETIVO: Analisar, comparativamente, doses de radiação em volumes alvos e órgãos de risco entre planejamentos conformados e não conformados em pacientes com câncer de próstata. MATERIAIS E MÉTODOS: No presente trabalho foram analisados planejamentos de 40 pacientes portadores de câncer de próstata. Foram realizados planejamentos conformados, não conformados isocêntricos e não conformados utilizando a distância fonte-superfície, simulados para cada caso, para comparação das doses em volumes alvos e órgãos de risco. Para a comparação foram analisados os histogramas de dose e volume para volumes alvos e órgãos de risco. RESULTADOS: As medianas das doses foram significativamente menores no planejamento conformado analisando-se os seguintes volumes no reto: 25%, 40% e 60%. As medianas das doses foram significativamente menores no planejamento conformado analisando-se os seguintes volumes na bexiga: 30% e 60%. As doses medianas foram significativamente menores no planejamento conformado analisando-se as articulações coxofemorais direita e esquerda. As doses máximas, médias e medianas no volume alvo clínico e no volume alvo planejado foram significativamente maiores no planejamento conformado. CONCLUSÃO: O presente estudo demonstrou que por meio do planejamento conformado em pacientes com câncer de próstata é possível entregar doses maiores no volume alvo e doses menores em órgãos de risco.

Magnetic resonance imaging (MRI) anatomy of the prostate and application of MRI in radiotherapy planning

Radiotherapy planning for prostate carcinoma has traditionally been performed on computed tomography (CT)-images, on which both the high dose areas (prostate with or without seminal vesicles) as well as the low dose areas (surrounding structures, such as the rectum and bladder) are anatomically delineated. However, magnetic resonance imaging (MRI) provides much more information than CT; it can superbly demonstrate the internal prostatic anatomy, prostatic margins and the extent of prostatic tumours. Hence, MRI becomes a powerful tool to improve the accuracy of planning delineations in radiotherapy for prostate carcinoma and is rapidly gaining popularity in the radiotherapy community. The present paper reviews some important anatomical landmarks and acquisition protocols relevant to radiotherapy planning and explains the rationale and importance of close collaboration between radiotherapists and radiologists in optimizing radiotherapy for patients with prostate carcinoma.

Analysis of toxicity in patients with high risk prostate cancer treated with intensity-modulated pelvic radiation therapy and simultaneous integrated dose escalation to prostate area

BACKGROUND AND PURPOSE

To report the treatment-related morbidity in patients with prostate cancer treated with an optimized pelvic intensity-modulated radiation therapy (IMRT) and simultaneous integrated dose escalation to prostate/prostate bed.

MATERIALS AND METHODS

Between November 2003 and May 2006, 55 patients with localized prostate cancer and >15% risk of lymph node involvement were treated with pelvic IMRT and simultaneous dose escalation to prostate area. Twenty-four patients received a radical radiation therapy program, and the remaining thirty-one patients received a postoperative irradiation as adjuvant treatment or after biochemical or macroscopic local/regional relapse. After a customized immobilization all patients underwent contrast-enhanced CT. On the CT slices CTV1 and CTV2 were delineated. CTV(1) included the prostate and seminal vesicles or prostate bed. CTV(2) consisted of CTV(1) plus pelvic nodes. CTV(1) and CTV(2) were then expanded by 0.5 and 1cm, respectively, to generate the planning target volumes. IMRT treatment plans were generated using commercial inverse planning software. Total doses of 66-80 Gy and 50-59 Gy in 33-40 fractions were prescribed to the prostate area and pelvis, respectively. The worst acute and late rectal, intestinal and GU toxicities during and after treatment were scored according to the EORTC/RTOG scales.

RESULTS

The IMRT dose distribution provided excellent PTV coverage and satisfying sparing of all the organs at risk, with no patient experiencing >grade 2 acute or late toxicities. Patients without acute grade 2 intestinal, rectal, and GU toxicity were 91%, 71%, and 63%, respectively. After a median follow-up of 19 months (interquartile range of 9 to 28 months), late grade 2 toxicity was detected only for rectum, with an actuarial 2-year rate of freedom from G2 rectal bleeding of 92%. (CI 95% 0.83-0.99.)

CONCLUSIONS

Pelvic IMRT and simultaneous dose escalation to prostate area is a well-tolerated technique in patients with prostate cancer requiring treatment of pelvic lymph nodes, and seems to be associated with a lower frequency and severity of side effects when compared with conventional techniques reported in other series.

Tomotherapy for prostate adenocarcinoma: A report on acute toxicity

BACKGROUND AND PURPOSE

To analyze the impact of Tomotherapy (TOMO) intensity modulated radiotherapy (IMRT) on acute gastrointestinal (GI) and genitourinary (GU) toxicity in prostate cancer.

MATERIALS AND METHODS

The records of 55 consecutively treated TOMO patients were reviewed. Additionally a well-matched group of 43 patients treated with LINAC-based step and shoot IMRT (LINAC) was identified. Acute toxicity was scored according to Radiation Therapy Oncology Group acute toxicity criterion.

RESULTS

The grade 2-3 acute GU toxicity rates for the TOMO vs. LINAC groups were 51% vs. 28% (p=0.001). Acute grade 2 GI toxicity was 25% vs. 40% (p=0.024), with no grade 3 GI toxicity in either group. In univariate analysis, androgen deprivation, prostate volume, pre-treatment urinary toxicity, and prostate dose homogeneity correlated with acute GI and GU toxicity. With multivariate analysis use of Tomotherapy, median bladder dose and bladder dose homogeneity remained significantly correlated with GU toxicity.

CONCLUSIONS

Acute GI toxicity for prostate cancer is improved with Tomotherapy at a cost of increased acute GU toxicity possibly due to differences in bladder and prostate dose distribution.

Chronic genitourinary and gastrointestinal toxicity of prostate cancer patients undergoing pelvic radiotherapy with intensity-modulated versus 4-field technique

PURPOSE

To compare chronic GU and GI toxicity of pelvic radiotherapy delivered using intensity-modulated radiotherapy (IMRT) versus conventional 4-field technique.

METHODS

The records of consecutive prostate cancer patients receiving RT at a single institution with a minimum follow-up of 120 days were reviewed; 48 of these patients received a prostate boost preceded by pelvic radiotherapy (PRT), 14 with IMRT (IM-PRT), and 34 with 4-field (4F-PRT). Dosimetric endpoints for the bladder, rectum, composite, and target for the PRT plans were compared using the 2-tailed t test. Late RTOG GU and GI toxicity were compared using the chi test. Ordered logit regression analyses were performed using all major patient, disease, and treatment factors as covariates.

RESULTS

IM-PRT demonstrated superior bladder and rectum dosimetric endpoints over 4F-PRT for the PRT portion of the treatment and for the composite treatment at the expense of higher target inhomogeneity in the PRT portion of the treatment plan. Late GU toxicity was significantly lower in the IM-PRT group (P < 0.001), whereas late GI toxicity was similar in both groups (P = 0.44). When considering a similar follow-up interval in both groups, however, the difference in GU toxicity only reached a trend (P = 0.10). The regression analyses showed that no factor, including IMRT, reached significance in predicting GU or GI toxicity.

CONCLUSION

Use of pelvic IMRT for prostate cancer patients was not associated with reduction of late GI toxicity but was associated with a small reduction of late GU toxicity. This reduction of late GU toxicity warrants further exploration in consortium studies.

Acute morbidity of proton therapy for prostate cancer: the Hyogo Ion Beam Medical Center experience

PURPOSE

To investigate the incidence and influencing factors of acute genitourinary (GU) and gastrointestinal morbidities in patients with prostate cancer treated with proton therapy.

METHODS AND MATERIALS

A total of 287 patients with histologically proven Stage cT1-T4N0M0 prostate cancer were treated with proton therapy between 2003 and 2004. Of these, 204 (71%) received neoadjuvant androgen suppression therapy. The patients were treated with 190-230-MeV protons using lateral-opposed techniques to a dose of 74 GyE. Dose-volume histogram analyses were performed. The incidence of acute morbidity was evaluated using the National Cancer Institute Common Toxicity Criteria, version 2.0. Clinical factors, including age, clinical target volume, initial prostate-specific antigen level, T stage, presence of diabetes mellitus, and the use of androgen suppression therapy, were investigated to determine whether those affected the incidence of acute GU morbidity.

RESULTS

None developed Grade 2 or higher acute gastrointestinal morbidity. In contrast, 111 (39%) and 4 (1%) patients experienced acute Grade 2 and Grade 3 GU morbidities, respectively. However, 87% of the patients were successfully relieved by the administration of a selective alpha-1 blocker. Multivariate analysis showed that a larger clinical target volume (p = 0.001) and the use of androgen suppression therapy (p = 0.017) were significant factors for the prediction of acute Grade 2-3 GU morbidity.

CONCLUSION

In our experience with proton therapy, a low incidence of acute gastrointestinal morbidity was observed. In contrast, the incidence of acute GU morbidity was similar to that in other reports of photon radiotherapy. Additional follow-up is warranted to elucidate the long-term safety and efficacy of proton therapy for prostate cancer.

Knock-down of Bcl-2 by antisense oligodeoxynucleotides induces radiosensitization and inhibition of angiogenesis in human PC-3 prostate tumor xenografts

Expression of the proto-oncogene Bcl-2 is associated with tumor progression. Bcl-2's broad expression in tumors, coupled with its role in resistance to chemotherapy and radiation therapy-induced apoptosis, makes it a rational target for anticancer therapy. Antisense Bcl-2 oligodeoxynucleotide (ODN) reagents have been shown to be effective in reducing Bcl-2 expression in a number of systems. We investigated whether treating human prostate cancer cells with antisense Bcl-2 ODN (G3139, oblimersen sodium, Genasense) before irradiation would render them more susceptible to radiation effects. Two prostate cancer cell lines expressing Bcl-2 at different levels (PC-3-Bcl-2 and PC-3-Neo) were subjected to antisense Bcl-2 ODN, reverse control (CTL), or mock treatment. Antisense Bcl-2 ODN alone produced no cytotoxic effects and was associated with G(1) cell cycle arrest. The combination of antisense Bcl-2 ODN with irradiation sensitized both cell lines to the killing effects of radiation. Both PC-3-Bcl-2 and PC-3-Neo xenografts in mice treated with the combination of antisense Bcl-2 ODN and irradiation were more than three times smaller by volume compared with xenografts in mice treated with reverse CTL alone, antisense Bcl-2 ODN alone, irradiation alone, or reverse CTL plus radiotherapy (P = 0.0001). Specifically, PC-3-Bcl-2 xenograft tumors treated with antisense Bcl-2 ODN and irradiation had increased rates of apoptosis and decreased rates of angiogenesis and proliferation. PC-3-Neo xenograft tumors had decreased proliferation only. This is the first study which shows that therapy directed at Bcl-2 affects tumor vasculature. Together, these findings warrant further study of this novel combination of Bcl-2 reduction and radiation therapy, as well as Bcl-2 reduction and angiogenic therapy.

Intensity-modulated radiation therapy for prostate cancer: Late morbidity and results on biochemical control

PURPOSE

To report on late morbidity and biochemical relapse-free survival (bRFS) after intensity-modulated radiation therapy (IMRT) for prostate cancer.

METHODS

Between 1998 and 2005 133 patients were treated with IMRT for T(1-4) N0 M0 prostate cancer. The median follow-up time was 36 months. In a first cohort, patients received a median planning target volume (PTV) dose of 74 Gy with a hard constraint on maximum rectum dose of 72 Gy (74R72, n=51). Later, median PTV and maximum rectum dose were increased to 76 and 74 Gy, respectively (76R74; n=82). We defined low-risk (n=20), intermediate-risk (n=70) and high-risk (n=43) groups. Androgen deprivation was given to patients in the intermediate- and high-risk group. Late gastro-intestinal (GI) and genito-urinary (GU) morbidity and biochemical relapse, in accordance with the ASTRO consensus, were recorded.

RESULTS

We observed grade 2 GI (17%) and GU (19%), grade 3 GI (1%) and GU (3%) late toxicities. Except for hematuria, the median duration of side-effects was 6 months. Biochemical relapse-free survival (bRFS) at 3 and 5 years was 88% and 83%, respectively, with a significantly better 3-year bRSF for the 76R74 than for the 74R72 group (p=0.01). Five-year bRFS for patients in the low-risk, intermediate-risk and high-risk group was 100%, 94% and 74%, respectively (p<0.01).

CONCLUSION

IMRT for localized or locally advanced prostate cancer combines low morbidity with excellent biochemical control.

Intensity modulated radiotherapy for localized prostate cancer: rigid compliance to dose-volume constraints as a warranty of acceptable toxicity?

BACKGROUND

To report the toxicity after intensity modulated radiotherapy (IMRT) for patients with localized prostate cancer, as a sole treatment or after radical prostatectomy.

METHODS

Between August 2001 and December 2003, 132 patients with prostate cancer were treated with IMRT and 125 were evaluable to acute and late toxicity analysis, after a minimum follow-up time of one year. Clinical and treatment data, including normal tissue dose-volume histogram (DVH) constraints, were reviewed. Gastro-intestinal (GI) and genito-urinary (GU) signs and symptoms were evaluated according to the Radiation Therapy Oncology Group (RTOG) toxicity scales. Median prescribed dose was 76 Gy. Median follow-up time was of 26.1 months.

RESULTS

From the 125 patients, 73 (58.4%) presented acute Grade 1 or Grade 2 GI and 97 (77.2%) presented acute Grade 1 or Grade 2 GU toxicity. Grade 3 GI acute toxicity occurred in only 2 patients (1.6%) and Grade 3 GU acute toxicity in only 3 patients (2.4%). Regarding Grade 1 and 2 late toxicity, 26 patients (20.8%) and 21 patients (16.8%) presented GI and GU toxicity, respectively. Grade 2 GI late toxicity occurred in 6 patients (4.8%) and Grade 2 GU late toxicity in 4 patients (3.2%). None patient presented any Grade 3 or higher late toxicity. Non-conformity to DVH constraints occurred in only 11.2% of treatment plans. On univariate analysis, no significant risk factor was identified for Grade 2 GI late toxicity, but mean dose delivered to the PTV was associated to higher Grade 2 GU late toxicity (p = 0.042).

CONCLUSION

IMRT is a well tolerable technique for routine treatment of localized prostate cancer, with short and medium-term acceptable toxicity profiles. According to the data presented here, rigid compliance to DHV constraints might prevent higher incidences of normal tissue complication.

Radiation proctopathy in the treatment of prostate cancer

PURPOSE

To compile and review data on radiation proctopathy in the treatment of prostate cancer with respect to epidemiology, clinical manifestations, pathogenesis, risk factors, and treatment.

METHODS

Medical literature databases including PubMed and Medline were screened for pertinent reports, and critically analyzed for relevance in the scope of our purpose.

RESULTS

Rectal toxicity as a complication of radiotherapy has received attention over the past decade, especially with the advent of dose-escalation in prostate cancer treatment. A number of clinical criteria help to define acute and chronic radiation proctopathy, but lack of a unified grading scale makes comparing studies difficult. A variety of risk factors, related to either radiation delivery or patient, are the subject of intense study. Also, a variety of treatment options, including medical therapy, endoscopic treatments, and surgery have shown varied results, but a lack of large randomized trials evaluating their efficacy prevents forming concrete recommendations.

CONCLUSION

Radiation proctopathy should be an important consideration for the clinician in the treatment of prostate cancer especially with dose escalation. With further study of possible risk factors, the advent of a standardized grading scale, and more randomized trials to evaluate treatments, patients and physicians will be better armed to make appropriate management decisions.

Use of benchmark dose–volume histograms for selection of the optimal technique between three-dimensional conformal radiation therapy and intensity-modulated radiation therapy in prostate cancer

PURPOSE

The aim of this study was to develop and validate our own benchmark dose-volume histograms (DVHs) of bladder and rectum for both conventional three-dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT), and to evaluate quantitatively the benefits of using IMRT vs. 3D-CRT in treating localized prostate cancer.

METHODS AND MATERIALS

During the implementation of IMRT for prostate cancer, our policy was to plan each patient with both 3D-CRT and IMRT. This study included 31 patients with T1b to T2c localized prostate cancer, for whom we completed double-planning using both 3D-CRT and IMRT techniques. The target volumes included prostate, either with or without proximal seminal vesicles. Bladder and rectum DVH data were summarized to obtain an average DVH for each technique and then compared using two-tailed paired t test analysis.

RESULTS

For 3D-CRT our bladder doses were as follows: mean 28.8 Gy, v60 16.4%, v70 10.9%; rectal doses were: mean 39.3 Gy, v60 21.8%, v70 13.6%. IMRT plans resulted in similar mean dose values: bladder 26.4 Gy, rectum 34.9 Gy, but lower values of v70 for the bladder (7.8%) and rectum (9.3%). These benchmark DVHs have resulted in a critical evaluation of our 3D-CRT techniques over time.

CONCLUSION

Our institution has developed benchmark DVHs for bladder and rectum based on our clinical experience with 3D-CRT and IMRT. We use these standards as well as differences in individual cases to make decisions on whether patients may benefit from IMRT treatment rather than 3D-CRT.

Combination of PTEN Gene Therapy and Radiation Inhibits the Growth of Human Prostate Cancer Xenografts

The resistance of prostate cancers to radiation therapy has been linked to abnormalities in overexpression of Bcl-2, an oncogene associated with inhibition of apoptosis. In this study, we evaluated whether the combination of the overexpression of phosphatase and tensin homolog (PTEN), a protein known to inhibit Bcl-2 expression, and radiation therapy would inhibit proliferation of Bcl-2-expressing human prostate cancer cells inoculated into the subcutis of athymic mice. Compared with either treatment alone, the combination of adenoviral vector-expressed PTEN (AdPTEN) and radiation (5 Gy) significantly inhibited xenograft tumor growth. Median tumor size on day 48 was 1030 mm3 in untreated controls, 656 mm3 in mice treated with radiation (5 Gy) alone, 640 mm3 in mice treated with AdPTEN alone, and 253 mm3 in mice treated with the combination (p<0.001). Treatment was well tolerated in all cases. Combination treatment also enhanced apoptosis (p=0.048), inhibited cellular proliferation (p=0.005), and inhibited tumor-induced neovascularity (p=0.030). Interestingly, this treatment increased apoptosis not only in tumor cells but also in tumor-associated endothelial cells. Together, these findings indicate that AdPTEN strongly inhibits the growth of human prostate tumors, especially when combined with radiation therapy, and that this effect is mediated by the induction of apoptosis and by the inhibition of angiogenesis and cellular proliferation.

Evaluation of bladder dose in intensity-modulated radiation therapy of the prostate

Day-to-day variation in bladder and rectal filling affects prostate location and positioning accuracy. Systems using ultrasonic localization or gold seed placement are most often used to help correct for these changes. At some institutions, patients are instructed to empty their rectum and fill their bladders prior to treatment in an attempt to standardize the prostate location, displace small bowel out of the radiation field, and move some of the bladder wall away from the high-dose area. Although instructed to come to treatment with a full bladder, it is presumed that there is variability in bladder filling each day of treatment, depending on the amount of fluids consumed and time to treatment. We have reviewed daily bladder volumes on a subset of 5 prostate patients, all of them prescribed to receive 7560 cGy in 42 fractions, and have evaluated the dosimetric consequences of bladder volume changes from full to two-third or one-third filling. All of these patients' positions were verified daily with ultrasonic localization. Those measurements have been used to help analyze the actual treated bladder volumes for comparison with the treatment plan. We find that, in general, maximum filling only occurred on the initial simulation/image acquisition day and was typically smaller on all the following treatment days. Based on our dose-volume model, we estimate that average bladder daily doses were 8-50% higher than predicted by the initial intensity-modulation radiation therapy (IMRT) plan.

Phase II study of a four-week hypofractionated external beam radiotherapy regimen for prostate cancer: Report on acute toxicity

PURPOSE

To evaluate the early side effects of a short course hypofractionated radiotherapy regimen in prostate cancer.

MATERIALS AND METHODS

Three institutions (IRE, AZ VUB, GUH) included 36 patients with T1-T3N0M0 prostate cancer in a phase II study. Patients were treated with 56 Gy in 16 fractions over 4 weeks. Early side effects were scored using the RTOG/EORTC criteria and the international prostate symptom index (IPSI) weekly during treatment and 1 and 2 months afterwards. The results were compared with two control groups of patients previously treated with conventional fractionation at AZ VUB (238 patients) and GUH (114 patients).

RESULTS

None of the patients experienced grade 3-4 toxicity. Grade 1-2 Gastro-intestinal (GI), grade 2 GI, grade 1-2 Genito-urinary (GU) and grade 2 GU toxicity occurred in 75%, 36%, 75% and 44% for the hypofractionation schedule. The corresponding figures were 25-44%, 6-29%, 47-53% and 16-44% for the control groups (p<0.01 for grade 1-2 GI and GU toxicity). Two months after treatment all GU and the majority of GI symptoms had resolved. The IPSI increased from (average +/-1 SD) 5.6+/-4 pre-treatment to 10.0+/-6 during week 2-4 and had normalized (5.2+/-4) two months after treatment.

CONCLUSIONS

Though no grade 3-4 side effects were observed, the investigated schedule results in a marked increase of grade 1-2 early side effects as compared to a conventional regimen. Side effects resolved within two months post-treatment.

Dosimetry and preliminary acute toxicity in the first 100 men treated for prostate cancer on a randomized hypofractionation dose escalation trial

PURPOSE

The alpha/beta ratio for prostate cancer is postulated to be between 1 and 3, giving rise to the hypothesis that there may be a therapeutic advantage to hypofractionation. The dosimetry and acute toxicity are described in the first 100 men enrolled in a randomized trial.

PATIENTS AND METHODS

The trial compares 76 Gy in 38 fractions (Arm I) to 70.2 Gy in 26 fractions (Arm II) using intensity modulated radiotherapy. The planning target volume (PTV) margins in Arms I and II were 5 mm and 3 mm posteriorly and 8 mm and 7 mm in all other dimensions. The PTV D95% was at least the prescription dose.

RESULTS

The mean PTV doses for Arms I and II were 81.1 and 73.8 Gy. There were no differences in overall maximum acute gastrointestinal (GI) or genitourinary (GU) toxicity acutely. However, there was a slight but significant increase in Arm II GI toxicity during Weeks 2, 3, and 4. In multivariate analyses, only the combined rectal DVH parameter of V65 Gy/V50 Gy was significant for GI toxicity and the bladder volume for GU toxicity.

CONCLUSION

Hypofractionation at 2.7 Gy per fraction to 70.2 Gy was well tolerated acutely using the planning conditions described.

Improving the morbidity of anorectal injury from pelvic radiotherapy

OBJECTIVE

Radiation anorectal injury due to pelvic radiotherapy for non intestinal cancer is a significant cause of morbidity which may limit the treatment dose required. Conservative treatment options are of limited value and surgery is reserved only for the most severe complications. This review addresses radioprotection of the anorectum and aims to increase awareness amongst surgeons of the strategies that have been in practice in order to minimize the side-effects of radiotherapy while preserving its therapeutic efficacy.

METHODS

This review is based on a literature search (Medline and NLM PubMed) with manual cross-referencing of all articles related to anorectal radiation injury.

RESULTS

Optimization of radiation dose, the use of radioprotective agents and improvement in radiation delivery are the main areas of development. There are few data on the potential of altered fractionation schedules in reducing anorectal injury. A few phase I and II studies suggest that the pharmacological agents amifostine and misoprostol could be beneficial in limiting radiation damage but larger phase III studies are awaited.

CONCLUSION

The introduction of 3-dimensional conformal radiation therapy and intensity modulated radiation therapy has been the most significant advance in reducing radiation morbidity.

Intensity-modulated versus conventional pelvic radiotherapy for prostate cancer: Analysis of acute toxicity

OBJECTIVES

To provide a single-institution analysis of the influence of pelvic intensity-modulated radiotherapy (RT) on acute genitourinary (GU) and gastrointestinal (GI) toxicity.

METHODS

The records of 610 consecutive patients with prostate cancer receiving RT were reviewed. Of these 610 patients, 49 had received a prostate boost preceded by pelvic RT (PRT), 15 intensity-modulated PRT (IM-PRT), and 34 four-field PRT (4F-PRT). The dosimetric endpoints for the bladder, rectum, and target for the PRT plans were compared using the paired t test; similar dosimetric analyses were done for the composite plans. Acute GU and GI toxicity were compared using the chi-square test. Ordered logit regression analyses were performed using all major treatment factors as covariates.

RESULTS

The bladder and rectum dosimetric endpoints were improved for IM-PRT compared with 4F-PRT for the PRT portion of the treatment plan (P = 0.06 and P = 0.03, respectively) and for the composite treatment plan (P = 0.04 and P = 0.01, respectively), at the expense of greater target inhomogeneity in the PRT portion of the treatment plan (P < 0.01). GU toxicity was significantly lower in the IM-PRT group (P < 0.001), and GI toxicity was similar in both groups (P = 0.637). The regression analyses showed that intensity-modulated RT for the pelvic portion of treatment was the only factor significantly predicting for GU toxicity (P = 0.05); no major treatment factor reached significance in predicting GI toxicity.

CONCLUSIONS

Compared with 4F-PRT, the use of IM-PRT improved dosimetric outcomes, was not associated with a reduction in acute GI toxicity, and was associated with a reduction in acute GU toxicity in the treatment of prostate cancer.

Dose-volume analysis of predictors for chronic rectal toxicity after treatment of prostate cancer with adaptive image-guided radiotherapy

PURPOSE

We analyzed our experience treating localized prostate cancer with image-guided off-line correction with adaptive high-dose radiotherapy (ART) in our Phase II dose escalation study to identify factors predictive of chronic rectal toxicity.

MATERIALS AND METHODS

From 1999-2002, 331 patients with clinical stage T1-T3N0M0 prostate cancer were prospectively treated in our Phase II 3D conformal dose escalation ART study to a median dose of 75.6 Gy (range, 63.0-79.2 Gy), minimum dose to confidence limited-planning target volume (cl-PTV) in 1.8 Gy fractions (median isocenter dose = 79.7 Gy). Seventy-four patients (22%) also received neoadjuvant/adjuvant androgen deprivation therapy. A patient-specific cl-PTV was constructed using 5 computed tomography scans and 4 sets of electronic portal images by applying an adaptive process to assure target accuracy and minimize PTV margin. For each case, the rectum (rectal solid) was contoured from the sacroiliac joints or rectosigmoid junction (whichever was higher) to the anal verge or ischial tuberosities (whichever was lower), with a median volume of 81.2 cc. The rectal wall was defined using the rectal solid with an individualized 3-mm wall thickness (median volume = 29.8 cc). Rectal wall dose-volume histogram was used to determine the prescribed dose. Toxicity was quantified using the National Cancer Institute Common Toxicity Criteria 2.0. Multiple dose-volume endpoints were evaluated for their association with chronic rectal toxicity.

RESULTS

Median follow-up was 1.6 years. Thirty-four patients (crude rate = 10.3%) experienced Grade 2 chronic rectal toxicity at a median interval of 1.1 years. Nine patients (crude rate = 2.7%) experienced Grade > or =3 chronic rectal toxicity (1 was Grade 4) at a median interval of 1.2 years. The 3-year rates of Grade > or =2 and Grade > or =3 chronic rectal toxicity were 20% and 4%, respectively. Acute toxicity predicted for chronic: Acute Grade 2-3 rectal toxicity (p < 0.001) including any acute rectal Grade 2-3 tenesmus (p = 0.02) and pain (p = 0.008) were significant predictors of chronic Grade > or =2 rectal toxicity. Any acute rectal toxicity (p = 0.001), any acute tenesmus (p = 0.03), and any acute diarrhea (p < 0.001) were also found to be predictive for chronic toxicity, as continuous variables. Dose-volume histogram predicted for chronic toxicity: Rectal wall absolute and relative V50, V60, V66.6, V70, and V72 and rectal solid relative V60-V72 were significantly associated with chronic Grade > or =2 rectal toxicity both as categorical and continuous variables (t test, linear regression) and when divided into subgroups (chi-square table). The chronic rectal toxicity Grade > or =2 risk was 9%, 18%, and 25% for the rectal wall relative V70 <15%, 25%-40%, and >40% respectively. The volume of rectum or rectal wall radiated to > or =50 Gy was a strong predictor for chronic rectal toxicity. Nonpredictive factors: Rectal solid/wall absolute or relative volumes irradiated to < or =40 Gy, dose level, and use of androgen deprivation were not found predictive.

CONCLUSIONS

In our ART dose escalation study, rectal wall or rectum relative > or =V50 are closely predictive for chronic rectal toxicity. If rectal dose-volume histogram constraints are used to select the dose level, the risk of chronic rectal toxicity will reflect the risk of toxicity of the selected constraint rather than the dose selected as found in our study using an adaptive process. To select the prescribed dose, different dose-volume histogram constraints may be used including the rectal wall V70. Patients experiencing acute rectal toxicity are more likely to experience chronic toxicity.

A phase III randomized, placebo-controlled, double-blind study of misoprostol rectal suppositories to prevent acute radiation proctitis in patients with prostate cancer

PURPOSE

Acute radiation proctitis is the most relevant complication of pelvic radiation and is still mainly treated supportively. Considering the negative impact of acute proctitis symptoms on patients' daily activities and the potential relationship between the severity of acute radiation injury and late damage, misoprostol was tested in the prevention of acute radiation-induced proctitis.

METHODS AND MATERIALS

A total of 100 patients who underwent radiotherapy for prostate cancer were entered into this phase III randomized, placebo-controlled, double-blind study with misoprostol or placebo suppositories. Radiation-induced toxicity was evaluated weekly during radiotherapy using the Common Toxicity Criteria.

RESULTS

Between the placebo and the misoprostol groups, no significant differences in proctitis symptoms occurred: 76% of patients in each group had Grade 1 toxicity, and 26% in the placebo group and 36% in the misoprostol group had Grade 2 toxicity. No differences were found in onset or symptom duration. Comparing the peak incidence of patients' toxicity symptoms, significantly more patients experienced rectal bleeding in the misoprostol group (p = 0.03).

CONCLUSION

Misoprostol given as a once-daily suppository did not decrease the incidence and severity of radiation-induced acute proctitis and may increase the incidence of acute bleeding.