Post-prostatectomy radiation therapy: Consensus guidelines of the Australian and New Zealand Radiation Oncology Genito-Urinary Group

[Postoperative radiotherapy of prostate cancer]

Between 10 and 40% of patients who have undergone a radical prostatectomy may have a biologic recurrence. Local or distant failure represents the possible patterns of relapse. Patients at high-risk for local relapse have extraprostatic disease, positive surgical margins or seminal vesicles infiltration or high Gleason score at pathology. Three phase-III randomized clinical trials have shown that, for these patients, adjuvant irradiation reduces the risk of tumoral progression without higher toxicity. Salvage radiotherapy for late relapse allows a disease control in 60-70% of the cases. Several research in order to improve the therapeutic ratio of the radiotherapy after prostatectomy are evaluate in the French Groupe d'Étude des Tumeurs Urogénitales (Gétug) and of the French association of urology (Afu). The Gétug-Afu 17 trial will provide answers to the question of the optimal moment for postoperative radiotherapy for pT3-4 R1 pN0 Nx patients, with the objective of comparing an immediate treatment to a differed early treatment initiated at biological recurrence. The Gétug-Afu 22 questions the place of a short hormonetherapy combined with image-guided, intensity-modulated radiotherapy (IMRT) in adjuvant situation for a detectable prostate specific antigen (PSA). The implementation of a multicenter quality control within the Gétug-Afu in order to harmonize a modern postoperative radiotherapy will allow the development of a dose escalation IMRT after surgery.

A Phase III trial to investigate the timing of radiotherapy for prostate cancer with high-risk features: background and rationale of the Radiotherapy -- Adjuvant Versus Early Salvage (RAVES) trial

OBJECTIVES

To test the hypothesis that observation with early salvage radiotherapy (SRT) is not inferior to 'standard' treatment with adjuvant RT (ART) with respect to biochemical failure in patients with pT3 disease and/or positive surgical margins (SMs) after radical prostatectomy (RP). To compare the following secondary endpoints between the two arms: patient-reported outcomes, adverse events, biochemical failure-free survival, overall survival, disease-specific survival, time to distant failure, time to local failure, cost utility analysis, quality adjusted life years and time to androgen deprivation.

PATIENTS AND METHODS

The Radiotherapy - Adjuvant Versus Early Salvage (RAVES) trial is a phase III multicentre randomised controlled trial led by the Trans Tasman Radiation Oncology Group (TROG), in collaboration with the Urological Society of Australia and New Zealand (USANZ), and the Australian and New Zealand Urogenital and Prostate Cancer Trials Group (ANZUP). In all, 470 patients are planned to be randomised 1:1 to either ART commenced at ≤4 months of RP (standard of care) or close observation with early SRT triggered by a PSA level of >0.20 ng/mL (experimental arm). Eligible patients have had a RP for adenocarcinoma of the prostate with at least one of the following risk factors: positive SMs ± extraprostatic extension ± seminal vesicle involvement. The postoperative PSA level must be ≤0.10 ng/mL. Rigorous investigator credentialing and a quality assurance programme are designed to promote consistent RT delivery among patients.

RESULTS

Trial is currently underway, with 258 patients randomised as of 31 October 2013. International collaborations have developed, including a planned meta-analysis to be undertaken with the UK Medical Research Council/National Cancer Institute of Canada Clinical Trials Group RADICALS (Radiotherapy and Androgen Deprivation In Combination with Local Surgery) trial and an innovative psycho-oncology sub-study to investigate a patient decision aid resource.

CONCLUSION

On the current evidence available, it remains unclear if ART is equivalent or superior to observation with early SRT.

Definition and visualisation of regions of interest in post-prostatectomy image-guided intensity modulated radiotherapy

Introduction

Standard post-prostatectomy radiotherapy (PPRT) image verification uses bony anatomy alignment. However, the prostate bed (PB) moves independently of bony anatomy. Cone beam computed tomography (CBCT) can be used to soft tissue match, so radiation therapists (RTs) must understand pelvic anatomy and PPRT clinical target volumes (CTV). The aims of this study are to define regions of interest (ROI) to be used in soft tissue matching image guidance and determine their visibility on planning CT (PCT) and CBCT.

Methods

Published CTV guidelines were used to select ROIs. The PCT scans (n = 23) and CBCT scans (n = 105) of 23 post-prostatectomy patients were reviewed. Details on ROI identification were recorded.

Results

Eighteen patients had surgical clips. All ROIs were identified on PCTs at least 90% of the time apart from mesorectal fascia (MF) (87%) due to superior image quality. When surgical clips are present, the seminal vesicle bed (SVB) was only seen in 2.3% of CBCTs and MF was unidentifiable. Most other structures were well identified on CBCT. The anterior rectal wall (ARW) was identified in 81.4% of images and penile bulb (PB) in 68.6%. In the absence of surgical clips, the MF and SVB were always identified; the ARW was identified in 89.5% of CBCTs and PB in 73.7%.

Conclusions

Surgical clips should be used as ROIs when present to define SVB and MF. In the absence of clips, SVB, MF and ARW can be used. RTs must have a strong knowledge of soft tissue anatomy and PPRT CTV to ensure coverage and enable soft tissue matching.

The importance of prostate bed tilt during postprostatectomy intensity-modulated radiotherapy

Variations in rectal and bladder filling can create a tilt of the prostate bed, which generates the potential for a geographic miss during postprostatectomy radiotherapy. The aim of this study is to assess the effect that bladder and rectum filling has on planning target volume angle, to determine a method to assess prostate bed tilt leading to potential geographic miss, and to discuss possible implementation issues. The cone-beam computed tomography images (n = 377) of 40 patients who received postprostatectomy radiotherapy with intensity-modulated radiotherapy were reviewed. The amount of tilt in the prostate bed was defined as the angle change between 2 surgical clips, one in the upper prostate bed and another in the lower. A potential geographic miss was defined as movement of any clip of more than 1cm in any direction or 0.5 cm posteriorly when aligned to bone anatomy. Variations in bladder and rectum size were correlated with the degree of prostate bed tilt, and the rate of potential geographic miss was determined. A possible clinical use of prostate bed tilt was then assessed for different imaging techniques. A tilt of more than 10° was seen in 20.2% of images, which resulted in a 57.9% geographic miss rate of the superior clip. When tilt remained within 10°, there was only a 9% rate of geographic miss. Potential geographic miss of the inferior surgical clip was rare, occurring in only 1.9% of all images reviewed. The most common occurrence when the prostate bed tilt increased by more than 10° was a smaller bladder and larger rectum (6.4% of all images). The most common occurrence when the prostate bed tilt decreased by more than 10° was a larger bladder and smaller rectum (1.3% of all images). Significant prostate bed tilt (>± 10°) occurred in more than 20% of images, creating a 58% rate of geographic miss. Greatest prostate bed tilt occurred when the bladder size increased or reduced by more than 2 cm or the superior rectum size increased by more than 1.5 cm or reduced by more than 1cm from the planned size. Using prostate bed tilt could be an effective measurement for assessing potential geographic miss on orthogonal images if volumetric imaging is unavailable.

Adjuvant radiotherapy after prostatectomy for prostate cancer in Japan: a multi-institutional survey study of the JROSG

In Japan, the use of adjuvant radiotherapy after prostatectomy for prostate cancer has not increased compared with the use of salvage radiotherapy. We retrospectively evaluated the outcome of adjuvant radiotherapy together with prognostic factors of outcome in Japan. Between 2005 and 2007, a total of 87 patients were referred for adjuvant radiotherapy in 23 institutions [median age: 64 years (54-77 years), median initial prostate-specific antigen: 11.0 ng/ml (2.9-284 ng/ml), Gleason score (GS): 6, 7, 8, 9, 10 = 13.8, 35.6, 23.0, 27.6, 0%, respectively]. Rates of positive marginal status, seminal vesicle invasion (SVI) and extra-prostatic extension (EPE) were 74%, 26% and 64%, respectively. Median post-operative PSA nadir: 0.167 ng/ml (0-2.51 ng/ml). Median time from surgery to radiotherapy was 3 months (1-6 months). A total dose of ≥ 60 Gy and <65 Gy was administered to 69% of patients. The median follow-up time was 62 months. The 3- and 5-year biochemical relapse-free survival (bRFS) rates for all patients were 66.5% and 57.1%, respectively. The GS and marginal status (P = 0.019), GS and SVI (P = 0.001), marginal status and EPE (P = 0.017), type of hormonal therapy and total dose (P = 0.026) were significantly related. The 5-year bRFS rate was significantly higher in SVI-negative patients than SVI-positive patients (P = 0.001), and significantly higher in patients with post-operative PSA nadir ≤ 0.2 than in patients with post-operative PSA nadir >0.2 (P = 0.02), and tended to be more favorable after radiotherapy ≤ 3 months from surgery than >3 months from surgery (P = 0.069). Multivariate analysis identified SVI and post-operative PSA nadir as independent prognostic factors for bRFS (P = 0.001 and 0.018, respectively).

The impact of rectal and bladder variability on target coverage during post-prostatectomy intensity modulated radiotherapy

BACKGROUND AND PURPOSE

Accuracy when delivering post-prostatectomy intensity modulated radiotherapy (IMRT) is crucial. The aims of this study were to quantify prostate bed movement and determine what amount of bladder or rectum size variation creates the potential for geographic miss.

METHODS AND MATERIALS

The Cone Beam CT (CBCT) images (n=377) of forty patients who received post-prostatectomy IMRT with daily on-line alignment to bony anatomy were reviewed. Prostate bed movement was estimated using the location of surgical clips in the upper and lower sections of the PTV and correlated with rectal and bladder filling (defined as changes in the cross sectional diameter at defined levels). The number of potential geographic misses caused by bladder and rectum variation was calculated assuming a uniform CTV to PTV expansion of 1cm except 0.5 cm posteriorly.

RESULTS

Variations in bladder filling of >2 cm larger, ±1 cm, or >2 cm smaller occurred in 3.4%, 56.2%, and 15.1% of images respectively with potential geographic misses in the upper prostate bed of 61.5%, 9.9% and 26.3% respectively. Variations in rectal filling in the upper prostate bed of >1.5 cm larger, 1.5 cm larger to 1cm smaller, and >1cm smaller occurred in 17.2%, 75.6%, and 7.2% of images respectively. These variations resulted in geographic misses in the upper prostate bed in 29.2%, 12.3%, and 63.0% of images respectively. Variations in bladder and rectal filling in the lower prostate bed region had minimal impact on geographic misses.

CONCLUSIONS

Bladder and rectal size changes at treatment affect prostate bed coverage, especially in the upper aspect of the prostate bed. The greatest potential for geographic miss occurred when either the bladder increased in size or when the rectum became smaller. Ensuring a full bladder and empty rectum at simulation will minimise this risk. Our data also support anisotropic PTV margins with larger margins superiorly than inferiorly.

Conventional margins not sufficient for post-prostatectomy prostate bed coverage: an analysis of 477 cone-beam computed tomography scans

PURPOSE

To study prostate bed deformation, and compare coverage by 5 mm and 10mm posterior expansion PTV margins.

METHOD

Fifty patients who completed post-prostatectomy radiotherapy had two expansion margins applied to the planning CT CTV: PTV10 (10 mm isometrically) and PTV5 (5 mm posteriorly, 10 mm all other directions). The CTV was then contoured on 477 pre-treatment CBCTs, and PTV5 and PTV10 coverage of each CBCT-CTVs was assessed. The maximum distance from the planning CT CTV to the combined CTV of all CBCTs including the planning CT CTV was measured for the superior part of the prostate bed, and the inferior part of the prostate bed, for every patient.

RESULTS

The mean difference between largest and smallest CBCT-CTVs per patient was 18.7 cm(3) (range 6.3-34.2 cm(3)). Out of 477 CBCTs, there were 43 anterior geometric geographical misses for either PTV with a mean volume of 2.25 cm(3) (range 0.01-18.88 cm(3)). For PTV10, there were 26 posterior geometric geographical misses with a mean volume of 1.37 cm(3) (0.01-11.02 cm(3)). For PTV5, there were 46 posterior geometric geographical misses with a mean volume of 3.22 cm(3) (0.01-19.82 cm(3)). The maximum edge-to-edge distance for the superior prostate bed was anterior 19 mm, posterior 16 mm, left and right 7 mm. The maximum edge-to-edge distance for the inferior prostate bed was anterior 4mm, posterior 12 mm, left and right 7 mm.

CONCLUSION

This study supports differential margins for the superior and inferior portions of the prostate bed. Because of the large deformation of CTV volume seen, adaptive radiotherapy solutions should be investigated further.

Suggestion for the prostatic fossa clinical target volume in adjuvant or salvage radiotherapy after a radical prostatectomy

BACKGROUND AND PURPOSE

To assess the location of recurrent tumors and suggest the optimal target volume in adjuvant or salvage radiotherapy (RT) after a radical prostatectomy (RP).

MATERIAL AND METHODS

From January 2000 to December 2012, 113 patients had been diagnosed with suspected recurrent prostate cancer by MRI scan and received salvage RT in the Samsung Medical Center. This study assessed the location of the suspected tumor recurrences and used the inferior border of the pubic symphysis as a point of reference.

RESULTS

There were 118 suspect tumor recurrences. The most common site of recurrence was the anastomotic site (78.8%), followed by the bladder neck (15.3%) and retrovesical area (5.9%). In the cranial direction, 106 (87.3%) lesions were located within 30 mm of the reference point. In the caudal direction, 12 lesions (10.2%) were located below the reference point. In the transverse plane, 112 lesions (94.9%) were located within 10mm of the midline.

CONCLUSIONS

A MRI scan acquired before salvage RT is useful for the localization of recurrent tumors and the delineation of the target volume. We suggest the optimal target volume in adjuvant or salvage RT after RP, which includes 97% of suspected tumor recurrences.

Contemporary issues in radiotherapy for clinically localized prostate cancer

Radiotherapy is a valid curative alternative to surgery for prostate cancer. However, patient selection is critical to ensure patients obtain benefits from therapy delivered with curative intent. Dose-escalated radiation has been shown to improve patient outcomes, facilitated by development of robust image guidance and better target delineation imaging technologies. These concepts have also rekindled interest in hypofractionated radiotherapy in the forms of stereotactic body radiotherapy and brachytherapy. Postprostatectomy radiotherapy also improves long-term biochemical outcome in men at high risk of local recurrence.

Adjuvant and salvage radiation therapy after prostatectomy: American Society for Radiation Oncology/American Urological Association guidelines

PURPOSE

The purpose of this guideline was to provide a clinical framework for the use of radiation therapy after radical prostatectomy as adjuvant or salvage therapy.

METHODS AND MATERIALS

A systematic literature review using PubMed, Embase, and Cochrane database was conducted to identify peer-reviewed publications relevant to the use of radiation therapy after prostatectomy. The review yielded 294 articles; these publications were used to create the evidence-based guideline statements. Additional guidance is provided as Clinical Principles when insufficient evidence existed.

RESULTS

Guideline statements are provided for patient counseling, use of radiation therapy in the adjuvant and salvage contexts, defining biochemical recurrence, and conducting a restaging evaluation.

CONCLUSIONS

Physicians should offer adjuvant radiation therapy to patients with adverse pathologic findings at prostatectomy (ie, seminal vesicle invastion, positive surgical margins, extraprostatic extension) and salvage radiation therapy to patients with prostate-specific antigen (PSA) or local recurrence after prostatectomy in whom there is no evidence of distant metastatic disease. The offer of radiation therapy should be made in the context of a thoughtful discussion of possible short- and long-term side effects of radiation therapy as well as the potential benefits of preventing recurrence. The decision to administer radiation therapy should be made by the patient and the multidisciplinary treatment team with full consideration of the patient's history, values, preferences, quality of life, and functional status. The American Society for Radiation Oncology and American Urological Association websites show this guideline in its entirety, including the full literature review.

Endorectal balloons in the post prostatectomy setting: do gains in stability lead to more predictable dosimetry?

PURPOSE

To perform a comparative study assessing potential benefits of endorectal-balloons (ERB) in post-prostatectomy patients.

METHOD AND MATERIALS

Ten retrospective post-prostatectomy patients treated without ERB and ten prospective patients treated with the ERB in situ were recruited. All patients received IMRT and IGRT using kilovoltage cone-beam computed tomography (kVCBCT). kVCBCT datasets were registered to the planning dataset, recontoured and the original plan recalculated on the kVCBCTs to recreate anatomical conditions during treatment. The imaging, structure and dose data were imported into in-house software for the assessment of geometric variation and cumulative equivalent uniform dose (EUD) in the two groups.

RESULTS

The difference in location (ΔCOV) for the bladder between planning and each CBCT was similar for each group. The range of mean ΔCOV for the rectum was 0.15-0.58 cm and 0.15-0.59 cm for the non-ERB and ERB groups. For superior-CTV and inferior-CTV the difference between planned and delivered D95% (mean ± SD) for the non-ERB group was 2.1 ± 6.0 Gy and -0.04 ± 0.20 Gy. While for the ERB group the difference in D95% was 8.7 ± 12.6 Gy and 0.003 ± 0.104 Gy.

CONCLUSIONS

The use of ERBs in the post-prostatectomy setting did improve geometric reproducibility of the target and surrounding normal tissues, however no improvement in dosimetric stability was observed for the margins employed.

Use of EORTC target definition guidelines for dose-intensified salvage radiation therapy for recurrent prostate cancer: results of the quality assurance program of the randomized trial SAKK 09/10

PURPOSE

Different international target volume delineation guidelines exist and different treatment techniques are available for salvage radiation therapy (RT) for recurrent prostate cancer, but less is known regarding their respective applicability in clinical practice.

METHODS AND MATERIALS

A randomized phase III trial testing 64 Gy vs 70 Gy salvage RT was accompanied by an intense quality assurance program including a site-specific and study-specific questionnaire and a dummy run (DR). Target volume delineation was performed according to the European Organisation for the Research and Treatment of Cancer guidelines, and a DR-based treatment plan was established for 70 Gy. Major and minor protocol deviations were noted, interobserver agreement of delineated target contours was assessed, and dose-volume histogram (DVH) parameters of different treatment techniques were compared.

RESULTS

Thirty European centers participated, 43% of which were using 3-dimensional conformal RT (3D-CRT), with the remaining centers using intensity modulated RT (IMRT) or volumetric modulated arc technique (VMAT). The first submitted version of the DR contained major deviations in 21 of 30 (70%) centers, mostly caused by inappropriately defined or lack of prostate bed (PB). All but 5 centers completed the DR successfully with their second submitted version. The interobserver agreement of the PB was moderate and was improved by the DR review, as indicated by an increased κ value (0.59 vs 0.55), mean sensitivity (0.64 vs 0.58), volume of total agreement (3.9 vs 3.3 cm(3)), and decrease in the union volume (79.3 vs 84.2 cm(3)). Rectal and bladder wall DVH parameters of IMRT and VMAT vs 3D-CRT plans were not significantly different.

CONCLUSIONS

The interobserver agreement of PB delineation was moderate but was improved by the DR. Major deviations could be identified for the majority of centers. The DR has improved the acquaintance of the participating centers with the trial protocol.

Prostate bed motion may cause geographic miss in post-prostatectomy image-guided intensity-modulated radiotherapy

INTRODUCTION

There is little data to guide radiation oncologists on appropriate margin selection in the post-prostatectomy setting. The aim of this study was to quantify interfraction variation in motion of the prostate bed to determine these margins.

METHODS

The superior and inferior surgical clips in the prostate bed were tracked on pretreatment cone beam CT images (n = 377) for 40 patients who had received post-prostatectomy radiotherapy. Prostate bed motion was calculated for the upper and lower segments by measuring the position of surgical clips located close to midline relative to bony anatomy in the axial (translational) and sagittal (tilt) planes. The frequency of potential geographic misses was calculated for either 1 cm or 0.5 cm posterior planning target volume margins.

RESULTS

The mean magnitude of movement of the prostate bed in the anterior-posterior, superior-inferior and left-right planes, respectively, were as follows: upper portion, 0.50 cm, 0.28 cm, 0.10 cm; lower portion, 0.18 cm, 0.18 cm, 0.08 cm. The random and systematic errors, respectively, of the prostate bed motion in the anterior-posterior, superior-inferior and left-right planes, respectively, were as follows: upper portion, 0.47 cm and 0.50 cm, 0.28 cm and 0.27 cm, 0.11 cm and 0.11 cm; lower portion, 0.17 cm and 0.18 cm, 0.17 cm and 0.19 cm, 0.08 cm and 0.10 cm. Most geographic misses occurred in the upper prostate bed in the anterior-posterior plane. The median prostate bed tilt was 1.8° (range -23.4° to 42.3°).

CONCLUSIONS

Variability was seen in all planes for the movement of both surgical clips. The greatest movement occurred in the anterior-posterior plane in the upper prostate bed, which could cause geographic miss of treatment delivery. The variability in the movement of the superior and inferior clips indicates a prostate bed tilt that would be difficult to correct with standard online matching techniques. This creates a strong argument for using anisotropic planning target volume margins in post-prostatectomy radiotherapy.

Adjuvant and salvage radiotherapy after prostatectomy: AUA/ASTRO Guideline

PURPOSE

The purpose of this guideline is to provide a clinical framework for the use of radiotherapy after radical prostatectomy as adjuvant or salvage therapy.

MATERIALS AND METHODS

A systematic literature review using the PubMed®, Embase, and Cochrane databases was conducted to identify peer-reviewed publications relevant to the use of radiotherapy after prostatectomy. The review yielded 294 articles; these publications were used to create the evidence-based guideline statements. Additional guidance is provided as Clinical Principles when insufficient evidence existed.

RESULTS

Guideline statements are provided for patient counseling, the use of radiotherapy in the adjuvant and salvage contexts, defining biochemical recurrence, and conducting a re-staging evaluation.

CONCLUSIONS

Physicians should offer adjuvant radiotherapy to patients with adverse pathologic findings at prostatectomy (i.e., seminal vesicle invasion, positive surgical margins, extraprostatic extension) and should offer salvage radiotherapy to patients with prostatic specific antigen or local recurrence after prostatectomy in whom there is no evidence of distant metastatic disease. The offer of radiotherapy should be made in the context of a thoughtful discussion of possible short- and long-term side effects of radiotherapy as well as the potential benefits of preventing recurrence. The decision to administer radiotherapy should be made by the patient and the multi-disciplinary treatment team with full consideration of the patient's history, values, preferences, quality of life, and functional status. Please visit the ASTRO and AUA websites (http://www.redjournal.org/webfiles/images/journals/rob/RAP%20Guideline.pdf and http://www.auanet.org/education/guidelines/radiation-after-prostatectomy.cfm) to view this guideline in its entirety, including the full literature review.

The PROCAINA (PROstate CAncer INdication Attitudes) Project (Part I): a survey among Italian radiation oncologists on postoperative radiotherapy in prostate cancer

PURPOSE

Radiotherapy (RT) has an established role in the postoperative treatment of prostate cancer patients with extracapsular extension, positive surgical margins or a detectable post-operative prostate-specific antigen (PSA). Despite the large number of patients treated with postoperative RT, some issues about optimal technique, doses, volumes, timing and association with androgen deprivation are still subject of debate. The aim of this survey was to determine the patterns of choice of Italian radiation oncologists in two different clinical cases of postoperative prostate cancer patients.

STUDY DESIGN

During the 2010 National Congress of the Italian Association of Radiation Oncology (AIRO), four clinical cases were presented to the attending radiation oncologists. Two of them were cases of postoperative prostate cancer, differing in T stage of the primary tumour according to the TNM classification, preoperative staging procedures, preoperative PSA (iPSA), Gleason score of biopsies and definitive pathological specimen after surgery and postoperative PSA. For each clinical case, the radiation oncologists were asked to: (a) give indication to new pre-treatment procedures for staging; b) give indication to postoperative treatment; (c) to define specifically, where indicated, the total dose, type of fractionation, treatment volumes, type of technique, type of image-guided setup control; (d) indicate whether adjuvant hormonal therapy should be prescribed; (e) define criteria that mostly influenced the prescription. A descriptive statistical analysis was then performed.

RESULTS

A total of 300 questionnaires were distributed amongst radiation oncologists attending the congress; 128 were completed and considered for this analysis (41%). Some important differences were shown in prescribing and performing postoperative radiotherapy, and some significant differences with international guidelines and data available from the literature were also reviewed and discussed.

CONCLUSIONS

Despite the results of clinical trials, significant differences still exist among Italian radiation oncologists in deciding postoperative treatment in prostate cancer patients. These patients probably deserve a more uniform approach based on updated, detailed and evidence-based recommendations.

Health-related quality of life using intensity-modulated radiation therapy for post-prostatectomy radiotherapy

INTRODUCTION

Post-prostatectomy radiotherapy (PPRT) with intensity-modulated radiation therapy (IMRT) has the potential to decrease toxicity by reducing dose to surrounding structures. We assessed its impact on health-related quality of life (HRQoL).

METHODS

PPRT patients were enrolled in a prospective HRQoL database. To be eligible, patients were required to be treated with IMRT and have a minimum of 15-month follow up. HRQoL was assessed at baseline, 3, 9 and 15-24 months using the Expanded Prostate Cancer Index Composite questionnaire. Higher scores reflected better HRQoL. Results were analysed as both population means and as individual scores where a moderate change was 10-20 points and a substantial change was >20 points.

RESULTS

There were 64 patients eligible and 83% of the cohort received salvage radiotherapy. Prescribed dose was 64 Gy in 32 fractions for adjuvant and 66 Gy in 33 fractions for salvage IMRT. Mean function scores for urinary, bowel and sexual domains were similar at baseline and 15 months (83.5, 94.2 and 16.9 vs. 82.2, 93.1 and 14.3, respectively). Mean global physical functioning (51.0 vs. 48.1) and mental functioning (51.6 vs. 54.2) showed no difference over time. Individual patient scores by 2 years showed a >20-point deterioration in urinary (12.5%), bowel (1.6%), sexual function (9.4%), physical functioning (3.1%) and mental functioning (1.6%).

CONCLUSION

This report on HRQoL following post-prostatectomy IMRT demonstrates no variation in mean scores in any domain and only 1.6% of patients reporting a greater than 20-point deterioration between baseline and 15-24 months in bowel function.

Constrained-beam inverse planning for intensity-modulated radiation therapy of prostate cancer patients with bilateral hip prostheses

Hip prostheses present a technical challenge in the planning of curative external beam radiation treatment for patients with prostate cancer. Bilateral prostheses compel planners to compromise between target coverage and avoidance of beam entry through the prostheses. Inverse planning systems given objectives to avoid dose to prostheses are overly restricted from allowing exit dose to them. We report a novel inverse planning technique for intensity-modulated radiation therapy of patients with prostate cancer and bilateral hip prostheses, by constraining beam characteristics rather than dose in the inverse planning process.

Improving the identification of male pelvic structures in post-prostatectomy patients on cone-beam CT: a region of interest atlas study

Purpose: To investigate the benefits of a regions of interest atlas for radiation therapists (RTTs) to aid in the identification of male pelvic structures in radiotherapy for prostate cancer, post-prostatectomy.

Methods and materials: Recruiting 35 radiation therapists from the Royal North Shore Hospital, a pretest- post-test study design was employed, with the atlas as the intervention. Using two patient CT data-sets, structure identification was scored as correct or incorrect and RT confidence levels were recorded using a visual analogue scale. The number of years of experience of each RT was also documented. Statistical significance was calculated using the Wilcoxon signed ranks test, paired samples t-test and chi-square tests.

Results: A statistically significant improvement was found between the pre-test and post-test in terms of both structure identification (p < 0.001) and confidence (p < 0.001) levels, with use of the atlas. The atlas was of use to staff of varying experience levels. Structures that were not normally used for target volume localisation were the hardest to identify.

Conclusion: Regions of interest atlases should be implemented to help identification of areas of anatomical complexity.

Australian & New Zealand Faculty of Radiation Oncology Genito-Urinary Group: 2011 consensus guidelines for curative radiotherapy for urothelial carcinoma of the bladder

Curative radiotherapy, with or without concurrent chemotherapy, is recognized as a standard treatment option for muscle-invasive bladder cancer. It is commonly used for two distinct groups of patients: either for those medically unfit for surgery, or as part of a 'bladder preserving' management plan incorporating the possibility of salvage cystectomy. However, in both situations, the approach to radiotherapy varies widely around the world. The Australian and New Zealand Faculty of Radiation Oncology Genito-Urinary Group recognised a need to develop consistent, evidence-based guidelines for patient selection and radiotherapy technique in the delivery of curative radiotherapy. Following a workshop convened in May 2009, a working party collated opinions and conducted a wide literature appraisal linking each recommendation with the best available evidence. This process was subject to ongoing re-presentation to the Faculty of Radiation Oncology Genito-Urinary Group members prior to final endorsement. These Guidelines include patient selection, radiation target delineation, dose and fractionation schedules, normal tissue constraints and investigational techniques. Particular emphasis is given to the rationale for the target volumes described. These Guidelines provide a consensus-based framework for the delivery of curative radiotherapy for muscle-invasive bladder cancer. Widespread input from radiation oncologists treating bladder cancer ensures that these techniques are feasible in practice. We recommend these Guidelines be adopted widely in order to encourage a uniformly high standard of radiotherapy in this setting, and to allow for better comparison of outcomes.

Three Years of Salvage IMRT for Prostate Cancer: Results of the Montpellier Cancer Center

Background. To assess the feasibility of salvage intensity-modulated radiation Therapy (IMRT) and to examine clinical outcome. Patients and Methods. 57 patients were treated with salvage IMRT to the prostate bed in our center from January, 2007, to February, 2010. The mean prescription dose was 68 Gy in 34 fractions. Forty-four patients received concomitant androgen deprivation. Results. Doses to organs at risk were low without altering target volume coverage. Salvage IMRT was feasible without any grade 3 or 4 acute gastrointestinal or urinary toxicity. With a median follow-up of 21 months, one grade 2 urinary and 1 grade ≥2 rectal late toxicities were reported. Biological relapse-free survival was 96.5% (2.3% (1/44) relapsed with androgen suppression and 7.7% (1/13) without). Conclusion. Salvage IMRT is feasible and results in low acute and chronic side-effects. Longer follow-up is warranted to draw conclusions in terms of oncologic control.

Postoperative radiotherapy in prostate cancer: the case of the missing target

PURPOSE

Postoperative radiotherapy (XRT) increases survival in high-risk prostate cancer patients. Approximately 50% of patients on long-term follow-up relapse despite adjuvant XRT and the predominant site of failure remains local. Four consensus guidelines define postoperative clinical target volume (CTV) in prostate cancer. We explore the possibility that inadequate CTV coverage is an important cause of local failure. This study evaluates the utility of preoperative magnetic resonance imaging (MRI) in defining prostate bed CTV.

METHODS AND MATERIALS

Twenty prostate cancer patients treated with postoperative XRT who also had preoperative staging MRI were included. The four guidelines were applied and the CTVs were expanded to create planning target volumes (PTVs). Preoperative MRIs were fused with postoperative planning CT scans. MRI-based prostate and gross visible tumors were contoured. Three-dimensional (3D) conformal four- and six-field XRT plans were developed and dose-volume histograms analyzed. Subtraction analysis was conducted to assess the adequacy of prostate/gross tumor coverage.

RESULTS

Gross tumor was visible in 18 cases. In all 20 cases, the consensus CTVs did not fully cover the MRI-defined prostate. On average, 35% of the prostate volume and 32% of the gross tumor volume were missed using six-field 3D treatment plans. The entire MRI-defined gross tumor volume was completely covered in only two cases (six-field plans). The expanded PTVs did not cover the entire prostate bed in 50% of cases. Prostate base and mid-zones were the predominant site of inadequate coverage.

CONCLUSIONS

Current postoperative CTV guidelines do not adequately cover the prostate bed and/or gross tumor based on preoperative MRI imaging. Additionally, expanded PTVs do not fully cover the prostate bed in 50% of cases. Inadequate CTV definition is likely a major contributing factor for the high risk of relapse despite adjuvant XRT. Preoperative imaging may lead to more accurate CTV definition, which should result in further improvements in survival for patients with high-risk prostate cancer.

Adjuvant radiotherapy following radical prostatectomy for prostate cancer

BACKGROUND

Men who have a radical prostatectomy (RP) for prostate cancer that does not involve lymph nodes, but extends beyond the prostate capsule into the seminal vesicles or to surgical margins, are at increased risk of relapse. In men with these high risk factors, radiotherapy (RT) directed at the prostate bed after surgery may reduce this risk, and be curative.

OBJECTIVES

To evaluate the effect of adjuvant RT following RP for prostate cancer in men with high risk features compared with RP.

SEARCH METHODS

We searched the Cochrane Prostatic Diseases and Urological Cancers Specialised Register (23 February 2011), the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE (January 1966 to February 2011), PDQ® (Physician Data Query) trial registry databases for ongoing studies (2 November 2010), reference lists from selected studies and reviews, and handsearched relevant conference proceedings.

SELECTION CRITERIA

Randomised controlled trials (RCT) comparing RP followed by RT with RP alone.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the studies for inclusion and bias and extracted data for analysis. Authors were contacted to clarify data and obtain missing information.

MAIN RESULTS

We found three RCTs involving 1815 men. Adjuvant RT following prostatectomy did not affect overall survival at 5 years (RD (risk difference) 0.00; 95% CI -0.03 to 0.03), but improved survival at 10 years (RD -0.11; 95% CI -0.20 to -0.02). Adjuvant RT did not improve prostate cancer-specific mortality at 5 years (RD -0.01; 95% CI -0.03 to 0.00). Adjuvant RT did not reduce metastatic disease at 5 years (RD -0.00; 95% CI -0.04 to 0.03), but reduced it at 10 years (RD -0.11; 95% CI -0.20 to -0.01). It improved local control at 5 and 10 years (RD -0.10; 95% CI -0.13 to -0.06 and RD -0.14; 95% CI -0.21 to -0.07, respectively), and biochemical progression-free survival at 5 years and 10 years (RD -0.16; 95% CI -0.21 to -0.11 and RD -0.29; 95% CI -0.39 to -0.19, respectively). There were no data for clinical disease-free survival. Adjuvant RT increased acute and late gastrointestinal toxicity [do you have the rd for this?], urinary stricture (RD 0.05; 95% CI 0.01 to 0.09) and incontinence (RD 0.04; 95% CI 0.01 to 0.08). It did not increase erectile dysfunction or degrade quality of life (RD 0.01; 95% CI -0.06 to -0.26), but with limited data.

AUTHORS' CONCLUSIONS

Adjuvant RT after RP improves overall survival and reduces the rate of distant metastases, but these effects are only evident with longer follow up. At 5 and 10 years it improves local control and reduces the risk of biochemical failure, although the latter is not a clinical endpoint. Moderate or severe acute and late toxicity is minimal. There is an increased risk of urinary stricture and incontinence, but no detriment to quality of life, based on limited data. Given that the majority of men who have undergone a RP have a longer life expectancy, radiotherapy should be considered for those with high-risk features following radical prostatectomy. The optimal timing is unclear.

Technology assessment of automated atlas based segmentation in prostate bed contouring

Background

Prostate bed (PB) contouring is time consuming and associated with inter-observer variability. We evaluated an automated atlas-based segmentation (AABS) engine in its potential to reduce contouring time and inter-observer variability.

Methods

An atlas builder (AB) manually contoured the prostate bed, rectum, left femoral head (LFH), right femoral head (RFH), bladder, and penile bulb of 75 post-prostatectomy cases to create an atlas according to the recent RTOG guidelines. 5 other Radiation Oncologists (RO) and the AABS contoured 5 new cases. A STAPLE contour for each of the 5 patients was generated. All contours were anonymized and sent back to the 5 RO to be edited as clinically necessary. All contouring times were recorded. The dice similarity coefficient (DSC) was used to evaluate the unedited- and edited- AABS and inter-observer variability among the RO. Descriptive statistics, paired t-tests and a Pearson correlation were performed. ANOVA analysis using logit transformations of DSC values was calculated to assess inter-observer variability.

Results

The mean time for manual contours and AABS was 17.5- and 14.1 minutes respectively (p = 0.003). The DSC results (mean, SD) for the comparison of the unedited-AABS versus STAPLE contours for the PB (0.48, 0.17), bladder (0.67, 0.19), LFH (0.92, 0.01), RFH (0.92, 0.01), penile bulb (0.33, 0.25) and rectum (0.59, 0.11). The DSC results (mean, SD) for the comparison of the edited-AABS versus STAPLE contours for the PB (0.67, 0.19), bladder (0.88, 0.13), LFH (0.93, 0.01), RFH (0.92, 0.01), penile bulb (0.54, 0.21) and rectum (0.78, 0.12). The DSC results (mean, SD) for the comparison of the edited-AABS versus the expert panel for the PB (0.47, 0.16), bladder (0.67, 0.18), LFH (0.83, 0.18), RFH (0.83, 0.17), penile bulb (0.31, 0.23) and rectum (0.58, 0.09). The DSC results (mean, SD) for the comparison of the STAPLE contours and the 5 RO are PB (0.78, 0.15), bladder (0.96, 0.02), left femoral head (0.87, 0.19), right femoral head (0.87, 0.19), penile bulb (0.70, 0.17) and the rectum (0.89, 0.06). The ANOVA analysis suggests inter-observer variability among at least one of the 5 RO (p value = 0.002).

Conclusion

The AABS tool results in a time savings, and when used to generate auto-contours for the femoral heads, bladder and rectum had superior to good spatial overlap. However, the generated auto-contours for the prostate bed and penile bulb need improvement.

Endorectal balloon reduces anorectal doses in post-prostatectomy intensity-modulated radiotherapy

BACKGROUND AND PURPOSE

To investigate the effect of an endorectal balloon (ERB) on anal wall (Awall) and rectal wall (Rwall) doses in high-dose post-prostatectomy intensity-modulated radiotherapy (IMRT).

MATERIALS AND METHODS

For 20 patients, referred for salvage IMRT after prostatectomy for prostate cancer, two planning CT-scans were performed: one with and one without an air-filled ERB. A planning target volume (PTV) was defined, using international guidelines. Furthermore, the Awall and Rwall were delineated. In both the scans, IMRT plans were generated with a prescribed dose of 70 Gy. The mean dose (D(mean)), maximum dose, minimum dose, and volumes exposed to doses ranging from ≥ 20 to ≥ 70 Gy (V(20)-V(70)) to the Awall and Rwall were calculated. Finally, inner Rwall surface areas exposed to doses ranging from ≥ 20 to ≥ 70 Gy (A(20)-A(70)) were calculated. Dose-parameters were compared between plans with and without ERB.

RESULTS

All Awall parameters, except V(70), were significantly reduced by the ERB with an overall D(mean) reduction of 6 Gy. Absolute reductions in dose-volume parameters varied from 5% to 11%. Significantly reduced Rwall V(30), V(40), and A(40) were observed with ERB, irrespective of the target volume size.

CONCLUSION

ERB application significantly reduces Awall and to a lesser degree Rwall doses in high-dose post-prostatectomy IMRT.

Postoperative intensity modulated radiation therapy in high risk prostate cancer: a dosimetric comparison

The aim of this study was to compare intensity-modulated radiation therapy (IMRT) with 3D conformal technique (3D-CRT), with respect to target coverage and irradiation of organs at risk for high dose postoperative radiotherapy (PORT) of the prostate fossa. 3D-CRT and IMRT treatment plans were compared with respect to dose to the rectum and bladder. The dosimetric comparison was carried out in 15 patients considering 2 different scenarios: (1) exclusive prostate fossa irradiation, and (2) pelvic node irradiation followed by a boost on the prostate fossa. In scenario (1), a 3D-CRT plan (box technique) and an IMRT plan were calculated and compared for each patient. In scenario (2), 3 treatment plans were calculated and compared for each patient: (a) 3D-CRT box technique for both pelvic (prophylactic nodal irradiation) and prostate fossa irradiation (3D-CRT only); (b) 3D-CRT box technique for pelvic irradiation followed by an IMRT boost to the prostatic fossa (hybrid 3D-CRT and IMRT); and (c) IMRT for both pelvic and prostate fossa irradiation (IMRT only). For exclusive prostate fossa irradiation, IMRT significantly reduced the dose to the rectum (lower Dmean, V50%, V75%, V90%, V100%, EUD, and NTCP) and the bladder (lower Dmean, V50%, V90%, EUD and NTCP). When prophylactic irradiation of the pelvis was also considered, plan C (IMRT only) performed better than plan B (hybrid 3D-CRT and IMRT) as respect to both rectum and bladder irradiation (reduction of Dmean, V50%, V75%, V90%, equivalent uniform dose [EUD], and normal tissue complication probability [NTCP]). Plan (b) (hybrid 3D-CRT and IMRT) performed better than plan (a) (3D-CRT only) with respect to dose to the rectum (lower Dmean, V75%, V90%, V100%, EUD, and NTCP) and the bladder (Dmean, EUD, and NTCP). Postoperative IMRT in prostate cancer significantly reduces rectum and bladder irradiation compared with 3D-CRT.

Prospective randomized double-blind pilot study of site-specific consensus atlas implementation for rectal cancer target volume delineation in the cooperative group setting

PURPOSE

Variations in target volume delineation represent a significant hurdle in clinical trials involving conformal radiotherapy. We sought to determine the effect of a consensus guideline-based visual atlas on contouring the target volumes.

METHODS AND MATERIALS

A representative case was contoured (Scan 1) by 14 physician observers and a reference expert with and without target volume delineation instructions derived from a proposed rectal cancer clinical trial involving conformal radiotherapy. The gross tumor volume (GTV), and two clinical target volumes (CTVA, including the internal iliac, presacral, and perirectal nodes, and CTVB, which included the external iliac nodes) were contoured. The observers were randomly assigned to receipt (Group A) or nonreceipt (Group B) of a consensus guideline and atlas for anorectal cancers and then instructed to recontour the same case/images (Scan 2). Observer variation was analyzed volumetrically using the conformation number (CN, where CN = 1 equals total agreement).

RESULTS

Of 14 evaluable contour sets (1 expert and 7 Group A and 6 Group B observers), greater agreement was found for the GTV (mean CN, 0.75) than for the CTVs (mean CN, 0.46-0.65). Atlas exposure for Group A led to significantly increased interobserver agreement for CTVA (mean initial CN, 0.68, after atlas use, 0.76; p = .03) and increased agreement with the expert reference (initial mean CN, 0.58; after atlas use, 0.69; p = .02). For the GTV and CTVB, neither the interobserver nor the expert agreement was altered after atlas exposure.

CONCLUSION

Consensus guideline atlas implementation resulted in a detectable difference in interobserver agreement and a greater approximation of expert volumes for the CTVA but not for the GTV or CTVB in the specified case. Visual atlas inclusion should be considered as a feature in future clinical trials incorporating conformal RT.

Prospective development of an individualised predictive model for treatment coverage using offline cone beam computed tomography surrogate measures in post-prostatectomy radiotherapy

The aim of this study is to prospectively evaluate and model surrogate explanatory variables (SEVs) of target coverage and rectal dose pertaining to soft tissue anatomy visualised on cone beam computed tomography (CBCT) for incorporation into post-prostatectomy treatment coverage verification protocols. Twenty post-prostatectomy patients treated with conformal prostate bed radiotherapy (64-74 Gy) underwent CBCT daily at fractions 1 to 5, and then weekly. Treatment coverage was defined on each CBCT using 'PTV95', percentage of the CBCT PTV covered by original treatment fields, and 'RECTD50', dose delivered to 50% of CBCT rectal volume by original treatment fields. Three candidate SEVs for treatment coverage were defined for each scan: anterior rectal wall movement, change in bladder length and bladder base movement. Both anterior rectal wall movement and increase in bladder length predicted for the decreased PTV95 (P < 0.001 for each). Anterior movement of the anterior rectal wall predicted for increased RECTD50 (P < 0.001). Predictive models for the PTV95 and RECTD50 that accept the significant SEVs as inputs were developed. We developed simple CBCT-acquired soft tissue anatomic surrogate measures that signal changes in target coverage and rectal dose during post-prostatectomy radiotherapy. Conventional bony anatomy patient position verification protocols were inadequate in accounting for soft tissue target and organ variation seen with CBCT.

Dosimetric comparison of three-dimensional conformal radiotherapy in salvage radiotherapy for PSA relapse after radical prostatectomy

The purpose of this study is to compare three-dimensional conformal radiotherapy (3D-CRT) plans in a setting of salvage radiotherapy after radical prostatectomy (RP) and to simulate whether dose escalation is possible with the most adequate 3D-CRT technique. This study included consecutive 10 patients underwent salvage radiotherapy (RT) for biochemical relapse of prostate cancer after RP. Normal structures included the rectum, bladder, and femoral head. For each patient, four different treatment plans including four fields RT (4F-RT), dynamic conformal arc radiotherapy (DCAT), six fields RT (6F-RT), and DCAT with rectum hollow-out technique (DCAT-HO), were created to entire the prostate bed. The parameters of the maximum and mean doses received by organs at risk (OAR), target coverage, dose homogeneity for the planning target volume (PTV) were compared. All plans were considered to be clinically tolerable for PTV coverage and dose homogeneity. The rectum sparing at the high dose area for DCAT-HO was considered to be the most superior to those for other three techniques by comparison of the dose delivered to a 1%, 5%, and 10% volume of the rectum. In the simulation of dose escalation to 70 Gy with DCAT-HO, OAR met a requirement of the dose-volume constraints. However, in the simulation of dose escalation to 72 Gy, the rectum that receives 60 to 65 Gy and bladder that receives 65 Gy exceeded the optimal dose-volume constraints. DCAT-HO was considered to be one of the most appropriate techniques in 3D-CRT if dose escalation to 70 Gy might be needed in a setting of salvage RT after RP in the future.

Radiation therapy of prostate cancer: rationale, pitfalls and the continuing prospect of success forged by medical physics

Radiation therapy aimed at curing prostate cancer forms a considerable workload in most contemporary radiation oncology departments. The wide range of currently available therapeutic strategies for this cancer and their increasing complexity further increases the impact these patients have within the treating unit. Grounded in basic anatomy, physiology and pathology, the rationale for the division of prostate cancers into different prognostic and therapeutic groups is discussed, and put into clinical context using the current research evidence base. Weaknesses in this evidence base are highlighted in relation to areas directly impacted on by the work of medical physics.

Verification of target position in the post-prostatectomy cancer patient using cone beam CT

We present the results of a pilot study designed to investigate methods that may be applied to develop a patient position correction protocol for the post-prostatectomy patient receiving radiotherapy. Imaging was carried out with cone beam CT (CBCT) to investigate its suitability for detecting changes in rectal and bladder volumes and movements of these organs relative to the treatment planning CT. Eligible patients were imaged daily during the first week of treatment and weekly thereafter. Surrogate explanatory variables, including distance from the isocentre to the anterior rectum and bladder length, were tested for their potential to substitute for contouring entire organs and predict for changes in coverage of the planning treatment volume (PTV) by the 95% isodose (PTV95) and the maximum dose delivered to 50% of the rectal volume (RECTD50). The PTV defined on the CBCT images was larger than that defined on the planning CT and resulted in a decrease in the PTV95. Bladder length correlated with bladder volume and changes in bladder volume were associated with a decrease in PTV95. Rectal volumes changed randomly during treatment. There was a trend for the rectum to move anteriorly as treatment progressed. CBCT may be used to define the PTV, rectum and bladder though the reason for an apparent increase in PTV on CBCT requires further investigation. The bladder length and distance to the anterior rectal wall are potential surrogate explanatory variables. Further studies will be designed to test values of these surrogates that predict the need for a change in isocentre position.

Early salvage radiotherapy for patients with PSA relapse after radical prostatectomy

PURPOSE

To assess the effectiveness of early salvage radiotherapy (RT) for patients with prostate-specific antigen (PSA) relapse after radical prostatectomy (RP) retrospectively.

METHODS

Fifty-one patients underwent salvage RT for biochemical relapse of prostate cancer initially treated with RP. All patients had persistent or rising PSA >0.20 ng/ml at some point after surgery, or three successive PSA elevations after a postoperative nadir if PSA was < or =0.20 ng/ml. Most (96%) of pre-RT PSA were less or equal to 0.50 ng/ml, and median value was 0.25 ng/ml (range, 0.05-0.90 ng/ml). Median RT dose was 60 Gy (range, 50-66 Gy). Multivariate Cox regression analysis was performed for PSA before RP and salvage RT, margin status, seminal vesicle involvement, extracapsular invasion, Gleason score, PSA doubling time (PSADT), and RT dose to identify significant predictors of biochemical outcome.

RESULTS

Median follow-up was 36 months. The 3-year biochemical no evidence of disease rate (bNED) was 55.1%. On multivariate analysis only the following factors were significantly associated with improved bNED: PSADT >3.0 months (P = 0.008), Gleason score < or =7 (P = 0.01), and RT dose > or =60 Gy (P = 0.028).

CONCLUSIONS

Although a total dose of 60 Gy was effective at a low pre-RT PSA levels with short follow-up, an RT dose > or =60 Gy resulted in superior biochemical outcomes even in patients with a pre-RT PSA < or =0.50 ng/ml.

Assessing the effect of a contouring protocol on postprostatectomy radiotherapy clinical target volumes and interphysician variation

PURPOSE

To compare postprostatectomy clinical target volume (CTV) delineation before and after the introduction of a contouring protocol and to investigate its effect on interphysician variability

METHODS AND MATERIALS

Six site-specialized radiation oncologists independently delineated a CTV on the computed tomography (CT) scans of 3 patients who had received postprostatectomy radiotherapy. At least 3 weeks later this was repeated, but with the physicians adhering to the contouring protocol from the Medical Research Council's Radiotherapy and Androgen Deprivation In Combination After Local Surgery (RADICALS) trial. The volumes obtained before and after the protocol were compared and the effect of the protocol on interphysician variability assessed.

RESULTS

An increase in mean CTV for all patients of 40.7 to 53.9 cm(3) was noted as a result of observing the protocol, with individual increases in the mean CTV of 65%, 15%, and 24% for Patients 1, 2, and 3 respectively. A reduction in interphysician variability was noted when the protocol was used.

CONCLUSIONS

Substantial interphysician variation in target volume delineation for postprostatectomy radiotherapy exists, which can be reduced by the use of a contouring protocol. The RADICALS contouring protocol increases the target volumes when compared with those volumes typically applied at our center. The effect of treating larger volumes on the therapeutic ratio and resultant toxicity should be carefully monitored, particularly if the same dose-response as documented in radical prostate radiotherapy applies to the adjuvant and salvage setting. Prostate cancer, Postprostatectomy, Radiotherapy, Target volume.