Phase III pilot study of dose escalation using conformal radiotherapy in prostate cancer: PSA control and side effects

A comparative study of rectal volume variation in patients with prostate cancer: A tertiary care center study

INTRODUCTION

Every day variations in rectal filling in prostate cancer radiotherapy can significantly alter the delivered dose distribution from what was intended. The goal of this study was to see if the time of treatment delivery affected the rectal filling.

METHODS

This is a retrospective study which included 50 patients with localized prostate cancer treated with volumetric modulated arc therapy (VMAT) to the primary and regional lymph nodes. Cone Beam Computed Tomography (CBCT) image-sets were done for all patient's daily setup verification. The radiation therapist contoured the rectum on all CBCT image sets. The rectal volumes delineated on CBCT and the planning CT image sets were compared. The change in rectal volumes between morning and afternoon treatments were calculated and compared.

RESULTS

A total of 1000 CBCT image sets were obtained on 50 patients in the morning and afternoon. The percentage variation of the CBCT rectal volumes over the planning CT scan was 16.57% in the AM group and 24.35% in the PM group.

CONCLUSION

The percentage change in rectal volume was significantly lesser in AM group compared to PM group and therefore morning treatments may result in dose distribution that is close to the intended dose distribution.

IMPLICATIONS FOR PRACTICE

In prostate cancer radiotherapy our study suggests that a simple technique of changing the time of treatment from afternoon to morning can help to reduce the rectal volume.

Impact of dose distribution on rotational setup errors in radiotherapy for prostate cancer

This study aimed to assess the impact of rotational setup errors on the target volume's dose distribution during radiotherapy for prostate cancer. A 6D robotic couch was used to describe the rotational setup error, and the dosage change in the target volume was analyzed using the planning evaluation factors. Treatment plans for three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT), and volumetric modulated arc radiotherapy (VMAT) were established after contouring the target volume and surrounding normal tissues on tomography obtained from the humanoid phantom. A 6D robotic couch was employed in the radiation room to describe the rotational setup errors of ±1° to ±5° in roll, yaw, and pitch, and cone beam computed tomography (CBCT) images were obtained. Furthermore, the dose distribution was extracted from the 3DCRT, IMRT, and VMAT treatment plans, dose mapping was performed on CBCT that depicts the rotational setup error. Target coverage(TC) decreased by 0.39% to 2.17% in roll, 0.43% to 2.59% in yaw, and 0.70% to 4.12% in pitch, respectively. In the comparison using the Radiation Therapy Oncology Group (RTOG) protocol criteria, when the rotational setup error of VMAT pitch was -2° or more, more than +1°, a target coverage of 95% or lower was shown, indicating the greatest effect among rotational setup errors. Furthermore, in 3DCRT, IMRT, and VMAT, the rotational setup error showed the greatest effect in pitch, and the dose change was larger in VMAT than in 3DCRT and IMRT. Therefore, specific rotational error due to pitch during radiotherapy for prostate cancer requires special consideration. Moreover, the more sophisticated and complex algorithms, such as VMAT, applied, the greater the dose change of target coverage due to rotational error; therefore, caution is required.

Dose-escalated radiotherapy for clinically localized and locally advanced prostate cancer

BACKGROUND

Treatments for clinically localized prostate cancer include radical prostatectomy, external beam radiation therapy, brachytherapy, active surveillance, hormonal therapy, and watchful waiting. For external beam radiation therapy, oncological outcomes may be expected to improve as the dose of radiotherapy (RT) increases. However, radiation-mediated side effects on surrounding critical organs may also increase.

OBJECTIVES

To assess the effects of dose-escalated RT in comparison with conventional dose RT for curative treatment of clinically localized and locally advanced prostate cancer.

SEARCH METHODS

We performed a comprehensive search using multiple databases including trial registries and other sources of grey literature, up until 20 July 2022. We applied no restrictions on publication language or status.

SELECTION CRITERIA

We included parallel-arm randomized controlled trials (RCTs) of definitive RT in men with clinically localized and locally advanced prostate adenocarcinoma. RT was dose-escalated RT (equivalent dose in 2 Gy [EQD2] ≥ 74 Gy, lesser than 2.5 Gy per fraction) versus conventional RT (EQD2 < 74 Gy, 1.8 Gy or 2.0 Gy per fraction). Two review authors independently classified studies for inclusion or exclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted data from the included studies. We performed statistical analyses by using a random-effects model and interpreted them according to the Cochrane Handbook for Systematic Reviews of Interventions. We used GRADE guidance to rate the certainty of the evidence of RCTs.

MAIN RESULTS

We included nine studies with 5437 men in an analysis comparing dose-escalated RT versus conventional dose RT for the treatment of prostate cancer. The mean participant age ranged from 67 to 71 years. Almost all men had localized prostate cancer (cT1-3N0M0). Primary outcomes Dose-escalated RT probably results in little to no difference in time to death from prostate cancer (hazard ratio [HR] 0.83, 95% CI 0.66 to 1.04; I2 = 0%; 8 studies; 5231 participants; moderate-certainty evidence). Assuming a risk of death from prostate cancer of 4 per 1000 at 10 years in the conventional dose RT group, this corresponds to 1 fewer men per 1000 (1 fewer to 0 more) dying of prostate cancer in the dose-escalated RT group. Dose-escalated RT probably results in little to no difference in severe RT toxicity of grade 3 or higher late gastrointestinal (GI) toxicity (RR 1.72, 95% CI 1.32 to 2.25; I2 = 0%; 8 studies; 4992 participants; moderate-certainty evidence); 23 more men per 1000 (10 more to 40 more) in the dose-escalated RT group assuming severe late GI toxicity as 32 per 1000 in the conventional dose RT group. Dose-escalated RT probably results in little to no difference in severe late genitourinary (GU) toxicity (RR 1.25, 95% CI 0.95 to 1.63; I2 = 0%; 8 studies; 4962 participants; moderate-certainty evidence); 9 more men per 1000 (2 fewer to 23 more) in the dose-escalated RT group assuming severe late GU toxicity as 37 per 1000 in the conventional dose RT group. Secondary outcomes Dose-escalated RT probably results in little to no difference in time to death from any cause (HR 0.98, 95% CI 0.89 to 1.09; I2 = 0%; 9 studies; 5437 participants; moderate-certainty evidence). Assuming a risk of death from any cause of 101 per 1000 at 10 years in the conventional dose RT group, this corresponds to 2 fewer men per 1000 (11 fewer to 9 more) in the dose-escalated RT group dying of any cause. Dose-escalated RT probably results in little to no difference in time to distant metastasis (HR 0.83, 95% CI 0.57 to 1.22; I2 = 45%; 7 studies; 3499 participants; moderate-certainty evidence). Assuming a risk of distant metastasis of 29 per 1000 in the conventional dose RT group at 10 years, this corresponds to 5 fewer men per 1000 (12 fewer to 6 more) in the dose-escalated RT group developing distant metastases. Dose-escalated RT may increase overall late GI toxicity (RR 1.27, 95% CI 1.04 to 1.55; I2 = 85%; 7 studies; 4328 participants; low-certainty evidence); 92 more men per 1000 (14 more to 188 more) in the dose-escalated RT group assuming overall late GI toxicity as 342 per 1000 in the conventional dose RT group. However, dose-escalated RT may result in little to no difference in overall late GU toxicity (RR 1.12, 95% CI 0.97 to 1.29; I2 = 51%; 7 studies; 4298 participants; low-certainty evidence); 34 more men per 1000 (9 fewer to 82 more) in the dose-escalated RT group assuming overall late GU toxicity as 283 per 1000 in the conventional dose RT group. Based on long-term follow-up (up to 36 months), dose-escalated RT may result or probably results in little to no difference in the quality of life using 36-Item Short Form Survey; physical health (MD -3.9, 95% CI -12.78 to 4.98; 1 study; 300 participants; moderate-certainty evidence) and mental health (MD -3.6, 95% CI -83.85 to 76.65; 1 study; 300 participants; low-certainty evidence), respectively.

AUTHORS' CONCLUSIONS

Compared to conventional dose RT, dose-escalated RT probably results in little to no difference in time to death from prostate cancer, time to death from any cause, time to distant metastasis, and RT toxicities (except overall late GI toxicity). While dose-escalated RT may increase overall late GI toxicity, it may result, or probably results, in little to no difference in physical and mental quality of life, respectively.

Dose-escalation in prostate cancer: Results of randomized trials

In 1998, an editorial from the International Journal of Radiation Oncology - Biology - Physics (IJROBP) on the occasion of the publication of Phase I by Zelefsky et al. on 3D radiotherapy dose escalation asked the question: "will more prove better?". More than 20 years later, several prospective studies have supported the authors' conclusions, making dose escalation a new standard in prostate cancer. The data from prospective randomized studies were ultimately disappointing in that they failed to show an overall survival benefit from dose escalation. However, there is a clear and consistent benefit in biochemical recurrence-free survival, which must be weighed on an individual patient basis against the potential additional toxicity of dose escalation. Techniques and concepts have become more and more precise, such as intensity modulated irradiation, simultaneous integrated boost, hypofractionated dose-escalation, pelvic irradiation with involved node boost or focal dose-escalation on gross recurrence after prostatectomy. The objective here was to summarize the prospective data on dose escalation in prostate cancer and in particular on recent advances in the field. In 2022, can we finally say that more has proven better?

Propensity score-matched analysis comparing dose-escalated intensity-modulated radiation therapy versus external beam radiation therapy plus high-dose-rate brachytherapy for localized prostate cancer

Purpose

Dose-escalated external beam radiation therapy (EBRT) and EBRT + high-dose-rate brachytherapy (HDR-BT) boost are guideline-recommended treatment options for localized prostate cancer. The purpose of this study was to compare long-term outcome and toxicity of dose-escalated EBRT versus EBRT + HDR-BT boost.

Methods

From 2002 to 2019, 744 consecutive patients received either EBRT or EBRT + HDR-BT boost, of whom 516 patients were propensity score matched. Median follow-up was 95.3 months. Cone beam CT image-guided EBRT consisted of 33 fractions of intensity-modulated radiation therapy with simultaneous integrated boost up to 76.23 Gy (D_Mean). Combined treatment was delivered as 46 Gy (D_Mean) EBRT, followed by two fractions HDR-BT boost with 9 Gy (D_90%). Propensity score matching was applied before analysis of the primary endpoint, estimated 10-year biochemical relapse-free survival (bRFS), and the secondary endpoints metastasis-free survival (MFS) and overall survival (OS). Prognostic parameters were analyzed by Cox proportional hazard modelling. Genitourinary (GU)/gastrointestinal (GI) toxicity evaluation used the Common Toxicity Criteria for Adverse Events (v5.0).

Results

The estimated 10-year bRFS was 82.0% vs. 76.4% (p = 0.075) for EBRT alone versus combined treatment, respectively. The estimated 10-year MFS was 82.9% vs. 87.0% (p = 0.195) and the 10-year OS was 65.7% vs. 68.9% (p = 0.303), respectively. Cumulative 5‑year late GU ≥ grade 2 toxicities were seen in 23.6% vs. 19.2% (p = 0.086) and 5‑year late GI ≥ grade 2 toxicities in 11.1% vs. 5.0% of the patients (p = 0.002); cumulative 5‑year late grade 3 GU toxicity occurred in 4.2% vs. 3.6% (p = 0.401) and GI toxicity in 1.0% vs. 0.3% (p = 0.249), respectively.

Conclusion

Both treatment groups showed excellent long-term outcomes with low rates of severe toxicity.

Procedural description and prospective evaluation of short-term outcome for the use of prostatic artery embolization in dogs with carcinoma of the prostate

OBJECTIVE

To describe the procedure of prostatic artery embolization (PAE) in dogs with prostatic carcinoma and to evaluate the short-term outcome for treated dogs.

ANIMALS

20 client-owned dogs with prostatic carcinomas between May 2014 and July 2017.

PROCEDURES

In this prospective cohort study, dogs with carcinoma of the prostate underwent PAE with fluoroscopic guidance. Before and after PAE, dogs underwent CT and ultrasonographic examinations of the prostate, and each owner completed a questionnaire about the dog's clinical signs. Results for before versus after PAE were compared.

RESULTS

Prostatic artery embolization was successfully performed in all 20 dogs. Tenesmus, stranguria, and lethargy were significantly less common 30 days after PAE (n = 2, 1, and 0 dogs, respectively), compared with before PAE (9, 10, and 6 dogs, respectively). Median prostatic volume was significantly less 30 days after PAE (14.8 cm3; range, 0.4 to 48.1 cm3; interquartile [25th to 75th percentile] range, 6.7 to 19.5 cm3), compared with before PAE (21.7 cm3; range, 2.9 to 77.7 cm3; interquartile range, 11.0 to 35.1 cm3). All dogs had a reduction in prostatic volume after PAE, with a median prostatic volume loss of 39.4% (95% CI, 20.3% to 59.3%).

CONCLUSIONS AND CLINICAL RELEVANCE

Prostatic artery embolization was associated with decreased prostate volume and improved clinical signs in this cohort. The short-term response to PAE appears promising, and evaluation of the long-term impact on survival time is needed.

Bladder filling volume variation between the first and second day of planning computed tomography for prostate cancer radiation therapy and correlation with renal function

AIM

During radiation therapy (RT) for prostate cancer, bladder filling helps exclude the organ from irradiation and reduces adverse effects. For RT planning, we performed computed tomography (CT) for 2 consecutive days to evaluate inter-day variations in organs such as the bladder. However, the patient factors that are associated with large intra-patient variations in bladder filling volume prior to RT are not known.

METHODS

This was a retrospective study of 97 prostate cancer patients who underwent CT for 2 consecutive days for RT planning between March 2015 and March 2020 and with confirmed water intake volume before the scans. Patients consumed 500 ml of water immediately after urination and underwent CT 30 min after the start of water intake; CT was performed under similar conditions over 2 consecutive days. Patient information was collected from the medical records taken before CT.

RESULTS

The median bladder filling volume was 102.8 cm³ (range: 31.7-774.0), and the median intra-patient bladder filling volume variation was 23.4 cm³ (range: 0.4-277.7). Univariate analysis revealed that the intra-patient variation was significantly larger in patients with an eGFR higher than the median (p = 0.003). No other factor showed correlations with the variation. As the larger bladder filling volume of the 2 consecutive days in patients increased (median 121.5 cm³ , range: 47.8-774.0), the intra-patient variation also increased.

CONCLUSION

Patients with a higher eGFR show greater variation in bladder filling volume, and caution should be exercised when applying RT in these patients.

Endoscopically delivered Purastat for the treatment of severe haemorrhagic radiation proctopathy: a service evaluation of a new endoscopic treatment for a challenging condition

BACKGROUND

A total of 30 000 people are treated with pelvic radiotherapy annually in the UK. Rectal bleeding is common following pelvic radiotherapy and one of the main causes is radiation proctopathy (RP). Six per cent develop severe bleeding from RP, leading to anaemia requiring iron +/- blood transfusion. There are very few safe, effective, evidence-based treatments. Purastat is a haemostatic agent licensed for gastrointestinal bleeding. It is a self-assembling peptide that forms a molecular mesh in contact with blood, thereby sealing blood vessels. There are numerous studies showing its efficacy and safety in various surgical/endoscopic settings. This service evaluation reports the first experience of the use of Purastat in RP.

METHODS

Consecutive patients attending pelvic radiation disease clinic with severe refractory RP were offered treatment with Purastat. This was defined as rectal bleeding into the pan±anaemia with no response to rectal sucralfate. Purastat was applied endoscopically at four weekly intervals up to three times, with more as required. Bleeding severity, endoscopic grade and haemoglobin were recorded.

RESULTS

Twenty-one patients were treated (18 men, median age 76 years) with a median of three treatments. Ten were on antithrombotics, 1 had thrombocytopenia and 13 had anaemia at baseline. Median episodes of bleeding reduced from 4.5 (0-27) to 2 (0-16) in the 7 days prior to the first and third treatment, respectively. Endoscopic grade was improved. Mean haemoglobin increased from 116.0 to 122.7. There were no complications.

CONCLUSION

Even in this cohort of severe refractory RP, there was an improvement in bleeding and endoscopic grade with Purastat. A randomised controlled trial is planned.

Radiogenomics Consortium Genome-Wide Association Study Meta-Analysis of Late Toxicity After Prostate Cancer Radiotherapy

BACKGROUND

A total of 10%-20% of patients develop long-term toxicity following radiotherapy for prostate cancer. Identification of common genetic variants associated with susceptibility to radiotoxicity might improve risk prediction and inform functional mechanistic studies.

METHODS

We conducted an individual patient data meta-analysis of six genome-wide association studies (n = 3871) in men of European ancestry who underwent radiotherapy for prostate cancer. Radiotoxicities (increased urinary frequency, decreased urinary stream, hematuria, rectal bleeding) were graded prospectively. We used grouped relative risk models to test associations with approximately 6 million genotyped or imputed variants (time to first grade 2 or higher toxicity event). Variants with two-sided Pmeta less than 5 × 10-8 were considered statistically significant. Bayesian false discovery probability provided an additional measure of confidence. Statistically significant variants were evaluated in three Japanese cohorts (n = 962). All statistical tests were two-sided.

RESULTS

Meta-analysis of the European ancestry cohorts identified three genomic signals: single nucleotide polymorphism rs17055178 with rectal bleeding (Pmeta = 6.2 × 10-10), rs10969913 with decreased urinary stream (Pmeta = 2.9 × 10-10), and rs11122573 with hematuria (Pmeta = 1.8 × 10-8). Fine-scale mapping of these three regions was used to identify another independent signal (rs147121532) associated with hematuria (Pconditional = 4.7 × 10-6). Credible causal variants at these four signals lie in gene-regulatory regions, some modulating expression of nearby genes. Previously identified variants showed consistent associations (rs17599026 with increased urinary frequency, rs7720298 with decreased urinary stream, rs1801516 with overall toxicity) in new cohorts. rs10969913 and rs17599026 had similar effects in the photon-treated Japanese cohorts.

CONCLUSIONS

This study increases the understanding of the architecture of common genetic variants affecting radiotoxicity, points to novel radio-pathogenic mechanisms, and develops risk models for testing in clinical studies. Further multinational radiogenomics studies in larger cohorts are worthwhile.

Hypofractionation for clinically localized prostate cancer

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Forward- and Inverse-Planned Intensity-Modulated Radiotherapy in the CHHiP Trial: A Comparison of Dosimetry and Normal Tissue Toxicity

AIMS

The CHHiP (Conventional or Hypofractionated High-dose Intensity Modulated Radiotherapy In Prostate Cancer; CRUK/06/016) trial investigated hypofractionated radiotherapy for localised prostate cancer. Forward- (FP) or inverse-planned (IP) intensity-modulated techniques were permitted. Dose-volume histogram and toxicity data were compared to explore the effects of planning method.

MATERIALS AND METHODS

In total, 337 participants with intermediate-risk disease and prospectively collected toxicity data were included. Patients were matched on prostate and rectum/bladder volumes and on radiotherapy dose for toxicity comparisons. The primary outcome was grade 2 or higher Radiation Therapy Oncology Group (RTOG) bowel or bladder toxicity at 2 years.

RESULTS

IP patients had smaller volumes of rectum irradiated to 50-70 Gy (P < 0.001); FP patients had smaller volumes of bladder irradiated to 74 Gy (P = 0.001). Acute grade 2 + bowel toxicity was worse with FP (27/53 [52%]; 11/53 [21%] IP; P = 0.0002); with no significant differences in acute urinary toxicity. At 2 years, RTOG grade 2 + bowel toxicity rates were FP 0/53 and IP 2/53 and RTOG grade 2 + bladder rates were FP 0/54 and IP 1/57.

CONCLUSIONS

Significant differences were found between dose-volume histograms from FP and IP methods. IP may result in small reductions in acute bowel toxicity but both techniques were associated with low rates of late radiotherapy side-effects.

Definition of fields margins for the optimized 2D radiotherapy of prostate carcinoma

Prostate cancer (PCa) is one of the most common malignancies in men both in western and developing countries. Radiotherapy (RT) is an important therapeutic option. New technologies (including 3D, intensity modulated RT, image-guided RT and, volumetric modulated arc therapy) have been introduced in the last few decades with progressive improvement of clinical outcomes. However, in many developing countries, the only treatment option is the traditional two-dimensional (2D) technique based on standard simulation. The guidelines for 2D field definition are still based on expert's opinions. The aim of the present study was to propose new practical guidelines for 2D fields definition based on 3D simulation in PCa. A total of 20 patients were enrolled. Computed tomography-simulation and pelvic magnetic resonance images were merged to define the prostate volumes. Clinical Target Volume (CTV) was defined using the European Organisation for Research and Treatment of Cancer guidelines in consideration of the four risk categories: Low, intermediate, and high risk with or without seminal vesicles involvement, respectively. Planning Target Volume (PTV) was defined by adding 10 mm to the CTV. For each category, two treatment plans were calculated using a cobalt source or 10 MV photons. Progressive optimization was achieved by evaluating 3D dose distribution. Finally, the optimal distances between field margins and radiological landmarks (bones and rectum with contrast medium) were defined. The results were reported in tabular form. Both field margins (PTV D_98% >95%) needed to adequately irradiate all patients and to achieve a similar result in 95% of the enrolled patients are reported. Using a group of patients with PCa and based on a 3D planning analysis, we propose new practical guidelines for PCa 2D-RT based on current criteria for risk category and CTV, and PTV definition.

Radical dose escalation by high-dose-rate brachytherapy for localized prostate cancer-Significance of prostate-specific antigen nadir level within 18 months as correlation for long-term biochemical control

PURPOSE

High-dose-rate brachytherapy (HDR-BT) for dose escalation in localized prostate cancer has been established as one standard treatment option. However, long-term results at followup (FU) ≥5 years are usually needed to ensure robustness of reported outcomes. Potential benefit of salvage therapy is, nevertheless, higher when relapse is diagnosed early. This study aimed to solve this dilemma by evaluating the prostate-specific antigen (PSA) nadir for early prediction of long-term biochemical control.

METHODS AND MATERIALS

Combined pelvis-external beam radiation/HDR-BT boost to EQD2 >100 Gy (α/β = 3) was performed in 459 consecutively treated patients. These patients with an FU ≥ 24 months were analyzed and stratified in PSA nadir (nPSA)-groups by PSA nadir within 18 months after radiotherapy (nPSA18). Kaplan-Meier/log-rank tests and Cox-regression models were used to compare the study endpoints.

RESULTS

The mean FU was 77 months. A PSA nadir within 18 months (nPSA18) <0.5 ng/mL was achieved in 222 patients with median time to reach nPSA18 of 7 months. The 5-year American Society of Therapeutic Radiology and Oncology (ASTRO) biochemical control (prostate-specific antigen disease-free survival) for the nPSA18 group <0.5 ng/mL was 89% and for the group ≥ 0.5 ng/mL, it was 78.6% (p = 0.011). nPSA18 was an independent predictor of cancer-specific survival, distant metastasis-free survival, and biochemical control (ASTRO) (p = 0.026, p = 0.020, and p = 0.01, respectively).

CONCLUSIONS

The present results suggest that the PSA nadir level within 18 months after radiotherapy may serve as an early parameter for long-term biochemical control according to ASTRO definitions following radical dose escalation by HDR-BT for prostate cancer. Excellent outcomes were associated with nPSA18 < 0.5 ng/mL.

Quality indicators of clinical cancer care for prostate cancer: a population-based study in southern Switzerland

Background

Quality of cancer care (QoCC) has become an important item for providers, regulators and purchasers of care worldwide. Aim of this study is to present the results of some evidence-based quality indicators (QI) for prostate cancer (PC) at the population-based level and to compare the outcomes with data available in the literature.

Methods

The study included all PC diagnosed on a three years period analysis (01.01.2011–31.12.2013) in the population of Canton Ticino (Southern Switzerland) extracted from the Ticino Cancer Registry database. 13 QI, approved through the validated Delphi methodology, were calculated using the “available case” approach: 2 for diagnosis, 4 for pathology, 6 for treatment and 1 for outcome. The selection of the computed QI was based on the availability of medical documentation. QI are presented as proportion (%) with the corresponding 95% confidence interval.

Results

700 PC were detected during the three-year period 2011–2013: 78.3% of them were diagnosed through a prostatic biopsy and for 72.5% 8 or more biopsy cores were taken. 46.5% of the low risk PC patients underwent active surveillance, while 69.2% of high risk PC underwent a radical treatment (radical prostatectomy, radiotherapy or brachytherapy) and 73.5% of patients with metastatic PC were treated with hormonal therapy. The overall 30-day postoperative mortality was 0.5%.

Conclusions

Results emerging from this study on the QoCC for PC in Canton Ticino are encouraging: the choice of treatment modalities seems to respect the international guidelines and our results are comparable to the scarce number of available international studies. Additional national and international standardisation of the QI and further QI population-based studies are needed in order to get a real picture of the PC diagnostic-therapeutic process progress through the definition of thresholds of minimal standard of care.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4604-2) contains supplementary material, which is available to authorized users.

The potential failure risk of the cone-beam computed tomography-based planning target volume margin definition for prostate image-guided radiotherapy based on a prospective single-institutional hybrid analysis

Background

The purpose of this study was to evaluate the impact of markerless on-board kilovoltage (kV) cone-beam computed tomography (CBCT)-based positioning uncertainty on determination of the planning target volume (PTV) margin by comparison with kV on-board imaging (OBI) with gold fiducial markers (FMs), and to validate a methodology for the evaluation of PTV margins for markerless kV-CBCT in prostate image-guided radiotherapy (IGRT).

Methods

A total of 1177 pre- and 1177 post-treatment kV-OBI and 1177 pre- and 206 post-treatment kV-CBCT images were analyzed in 25 patients who received prostate IGRT with daily localization by implanted FMs. Intrafractional motion of the prostate was evaluated between each pre- and post-treatment image with these two different techniques. The differences in prostate deviations and intrafractional motions between matching by FM in kV-OBI (OBI-FM) and matching by soft tissues in kV-CBCT (CBCT-ST) were compared by Bland-Altman limits of agreement. Compensated PTV margins were determined and compensated by references.

Results

Mean differences between OBI-FM and CBCT-ST in the anterior to posterior (AP), superior to inferior (SI), and left to right (LR) directions were − 0.43 ± 1.45, − 0.09 ± 1.65, and − 0.12 ± 0.80 mm, respectively, with R² = 0.85, 0.88, and 0.83, respectively. Intrafractional motions obtained from CBCT-ST were 0.00 ± 1.46, 0.02 ± 1.49, and 0.15 ± 0.64 mm, respectively, which were smaller than the results from OBI-FM, with 0.43 ± 1.90, 0.12 ± 1.98, and 0.26 ± 0.80 mm, respectively, with R² = 0.42, 0.33, and 0.16, respectively. Bland-Altman analysis showed a significant proportional bias. PTV margins of 1.5 mm, 1.4 mm, and 0.9 mm for CBCT-ST were calculated from the values of CBCT-ST, which were also smaller than the values of 3.15 mm, 3.66 mm, and 1.60 mm from OBI-FM. The practical PTV margin for CBCT-ST was compensated with the values from OBI-FM as 4.1 mm, 4.8 mm, and 2.2 mm.

Conclusions

PTV margins calculated from CBCT-ST might be underestimated compared to the true PTV margins. To determine a reliable CBCT-ST-based PTV margin, at least the systemic error Σ and the random error σ for on-line matching errors need to be investigated by supportive preliminary FM evaluation at least once.

Association between rectal bleeding and the absolute dose volume of the rectum following image-guided radiotherapy for patients with prostate cancer

The association between rectal bleeding and the received dose relative to the volume of the rectum is well established in prostate cancer patients who have undergone radiotherapy. The relative volume of the rectum is affected by the rectal anatomical volume, which depends on the definition of rectal length. Compared with the relative rectal volume, the absolute volume of the rectum may be more associated with rectal bleeding. The present study investigated the absolute volume of the rectum that may be used to predict late rectal bleeding following intensity-modulated radiotherapy (IMRT) and image-guided radiotherapy (IGRT). The cases of 82 patients of prostate cancer, who underwent IMRT and IGRT, were retrospectively evaluated by evaluating dose volume histograms. The median patient age was 73.4 years (range, 51.3-85.9 years). The median total prescribed dose was 76 Gy given in 38 fractions. The absolute and relative dose volumes of the rectum were evaluated by multivariate analysis, and the optimal dose to prevent rectal bleeding was determined. The actuarial ≥grade 1 rectal bleeding rate at 4 years was 4.5% (95% confidence interval, 1.5-13.4%) with a median observation period of 45.3 months. The absolute rectal volume (ml) treated with 60 Gy was the only significant risk factor for rectal bleeding (P<0.05), but the relative rectal volume (%) was not identified as a significant factor by the multivariate analysis. When the rectal volume of 5 or 10 ml received 60 Gy (D5cc and D10cc), rectal bleeding was expected to occur in 3.3 and 7.3% of the patients, respectively. Rectal D5cc ≤60 Gy is recommended to prevent late ≥grade 1 rectal bleeding in IGRT.

Safety and feasibility of prostate stereotactic ablative radiotherapy using multimodality imaging and flattening filter free

OBJECTIVE

To investigate feasibility and safety of stereotactic ablative radiotherapy in the management of prostate cancer while employing MR/CT fusion for delineation, fiducial marker seeds for positioning and Varian RapidArc with flattening filter free (FFF) delivery.

METHODS

41 patients were treated for low-intermediate risk prostate cancer with initial prostate-specific antigen of ≤20 ng ml-1, Gleason score 6-7. Patients had MR/CT fusion for delineation of prostate ±seminal vesicles. CT/MR fusion images were used for delineation and planned using flattening filter free modality. Verification on treatment was cone beam CT imaging with fiducial markers for matching. Patients had Radiation Therapy Oncology Group scoring for genitourinary and gastointestinal symptoms at baseline, week 4, 10 and 18.

RESULTS

Clinically acceptable plans were achieved for all patients, all plans achieved the objective clinical target volume D99% ≥ 95%, and for planning target volume D95% ≥ 95%. Rectum dose constraints were met for 95.1% for V18 Gy ≤ 35%, 80% V28 Gy ≤ 10%. A total of 32 (78.0%) plans achieved all rectum dose constraints. Grade 1 acute genitourinary symptoms were 53.7% of patients at baseline, 90.2% [95% CI (76.8-97.3%)] (p = 0.0005) at treatment 5, falling to 78.0% (62.4-89.4%) at week 4, and 75.0% (58.8-87.3%) by week 10 and 52.5% (36.1-68.5%) (p = 1.00) at week 18. Acute gastrointestinal symptoms were 5% at baseline, 46.3% [95% CI (30.7-62.6%)] at treatment 5, week 4 43.9% [95% CI (28.5-60.3%)], week 10 25.0% (11.1-42.3%), and declined slightly by week 18 [-20.095% CI (12.7-41.2)] p = 0.039. Overall 75.6% (31/41) of patients experienced Grade 1-2 toxicity during or after treatment.

CONCLUSION

This planning and delivery technique is feasible, safe and efficient. A homogeneous dose can be delivered to prostate with confidence, whilst limiting high dose to nearby structures. The use of this technology can be applied safely within further randomized study protocols. Advances in knowledge: Multimodality imaging for delineation and linac-based image-guided RT with FFF for the treatment of prostate stereotactic ablative radiotherapy.

Association of bladder dose with late urinary side effects in cervical cancer high-dose-rate brachytherapy

PURPOSE

The purpose of this work was to study the association between specific urinary sequelae and locally accumulated dose to the bladder wall and bladder neck in the treatment of cervical cancer with multifraction high-dose-rate (HDR) brachytherapy.

METHODS AND MATERIALS

A cohort of 60 cervical cancer patients, treated with both external beam and five HDR brachytherapy insertions between 2008 and 2014 at the BC Cancer Agency, was identified. The accumulated dose received over five brachytherapy sessions was evaluated for the bladder wall and bladder neck of each patient using dosimetric parameters calculated from deformably registered image data sets. These parameters were examined as potential predictors of urinary sequelae including hematuria, frequency, urgency, incontinence, stream, nocturia, and dysuria. Two different dichotomization schemes were evaluated for grouping patients into Case and Control groups. The two-sample Student's t test was used for normally distributed samples and the Mann-Whitney nonparametric U test for non-normal distributions.

RESULTS

A strong association between dose to the bladder neck and incontinence was found (p = 0.001). A statistically significant association (p < 0.05) was also observed between urgency and certain bladder-wall parameters.

CONCLUSIONS

Localized dose to the bladder neck is a potential predictor of urinary incontinence, whereas weaker associations were observed between urgency and some bladder-wall parameters.

Total abdominal irradiation exposure impairs cognitive function involving miR-34a-5p/BDNF axis

Radiotherapy is often employed to treat abdominal and pelvic malignancies, but is frequently accompanied by diverse acute and chronic local injuries. It was previously unknown whether abdominal and pelvic radiotherapy impairs distant cognitive dysfunction. In the present study, we demonstrated that total abdominal irradiation (TAI) exposure caused cognitive deficits in mouse models. Mechanically, microarray assay analysis revealed that TAI elevated the expression level of miR-34a-5p in small intestine tissues and peripheral blood (PD), which targeted the 3'UTR of Brain-derived neurotrophic factor (Bdnf) mRNA in hippocampus to mediate cognitive dysfunction. Tail intravenous injection of miR-34a-5p antagomir immediately after TAI exposure rescued TAI-mediated cognitive impairment via blocking the up-regulation of miR-34a-5p in PD, resulting in restoring the Bdnf expression in the hippocampus. More importantly, high throughput sequencing validated that the gut bacterial composition of mice was shifted after TAI exposure, which was retained by miR-34a-5p antagomir injection. Thus, our findings provide new insights into pathogenic mechanism underlying abdominal and pelvic radiotherapy-mediated distant cognitive impairment.

Improved outcomes with dose escalation in localized prostate cancer treated with precision image-guided radiotherapy

BACKGROUND AND PURPOSE

Dose-escalated radiotherapy (DE) improves outcomes in localized prostate cancer (PCa). The impact of DE in the context of image-guided radiotherapy (IGRT) remains unknown. Herein, we determined outcomes of three sequential cohorts treated with progressive DE-IGRT.

MATERIALS AND METHODS

We analyzed data from 1998 to 2012. Patients treated with radical radiotherapy were included, with three sequential institutional schedules: (A) 75.6Gy, (B) 79.8Gy, (C) 78Gy, with 1.8, 1.9 and 2Gy/fraction, respectively. IGRT consisted of fiducial markers and daily EPID (A, B) or CBCT (C).

RESULTS

961 patients were included, with median follow-up of 6.1y. 30.5%, 32.6% and 36.9% were treated in A, B and C, respectively. Risk category distribution was 179 (18.6%) low-, 653 (67.9%) intermediate- and 129 (13.5%) high-risk. PSA, T-category, androgen deprivation use and risk distribution were similar among groups. BCR (biochemical recurrence) was different (p<0.001) between A, B and C with 5-year rates of 23%, 17% and 9%, respectively (HR 2.68 [95% CI 1.87-3.85] and 1.92 [95% CI 1.33-2.78] for A and B compared to C, respectively). Findings were most significant in the intermediate-risk category. Metastasis, cause-specific-death and toxicities were not different between cohorts.

CONCLUSION

Our findings suggest continuous BCR improvement with progressive DE-IGRT. Prospective validation considering further DE with IGRT seems warranted.

A comparison of clinical outcomes between three-dimensional conformal radiotherapy and intensity-modulated radiotherapy for prostate cancer

BACKGROUND

Intensity-modulated radiation therapy (IMRT) reduces the dose delivered to organs at risk. However, there have been few direct comparisons of IMRT with conventional three-dimensional conformal radiotherapy (3DCRT). The aim of this study was to evaluate the clinical benefit of IMRT in terms of toxicity and biochemical control.

METHODS

The medical records of 203 consecutive patients with localized to non-metastatic (stage T1a-T3bN0M0) prostate cancer between 2007 and 2011 were retrospectively reviewed. The prescribed dose was 76 Gy delivered in 38 fractions in both the 3DCRT and IMRT treatment groups. The frequency of grade 2 or greater late gastrointestinal (GI) and genitourinary toxicity and biochemical control were estimated by the log-rank test and Cox proportional hazards model with and without adjustment by the propensity score for treatment choice.

RESULTS

A total of 159 patients were included in the study (3DCRT: 70 patients, IMRT: 89 patients). The median follow-up period was 4.7 years. The estimated 5-year cumulative risk of late GI toxicity was significantly lower in the IMRT group than in the 3DCRT group (3.6 vs 13.2%, respectively, p = 0.022). After adjustment by propensity score, IMRT remained associated with a lower risk of late GI toxicity (hazard ratio 0.22; 95% confidence interval 0.058-0.85; p = 0.028). The 5-year biochemical failure-free rate was 93.2% in the 3DCRT group and 95.4% in the IMRT group (non-significant difference).

CONCLUSIONS

The incidence of late GI toxicity was significantly lower in the IMRT group than in the 3DCRT group, while the biochemical control rates were no different between the two groups. These clinical data suggest the benefit of IMRT in the reduction of late GI toxicity.

Intravesical Glycosaminoglycan Replacement with Chondroitin Sulphate (Gepan(®) instill) in Patients with Chronic Radiotherapy- or Chemotherapy-Associated Cystitis

Background and Objective

Intravesical instillation of glycosaminoglycans is a promising option for the treatment of chronic cystitis, as it supports the regeneration of the damaged urothelial layer. We investigated the efficacy of short-term intravesical chondroitin sulphate treatment (six courses of instillation) in patients with chronic radiotherapy- or chemotherapy-associated cystitis.

Methods

This prospective, observational study included patients with chronic radiotherapy- or chemotherapy-associated cystitis, who received six once-weekly intravesical instillations of 0.2 % chondroitin sulphate 40 mL. Every week, patients recorded their symptoms and their benefits and tolerance of treatment, using a self-completed questionnaire.

Results

The study included 16 patients (mean age 68.5 years; 50 % male). During the study, a reduction in all evaluated parameters was observed. After one dose of chondroitin sulphate, symptom improvement was observed in 38 % of patients, and after the second dose, an additional 31 % of patients showed improvement. At week 6, 80 % of patients had either improved or were symptom free, and significant improvements in urinary urgency (p = 0.0082), pollakisuria (p = 0.0022), urge frequency (p = 0.0033) and lower abdominal pain (p = 0.0449) were observed. Haematuria, present in 9 of the 16 patients at baseline, was completely resolved in all cases after 6 weeks. The majority of patients (93 %) evaluated the tolerance of chondroitin sulphate as ‘good’ or ‘very good’. No treatment-related adverse events were reported.

Conclusion

Intravesical administration of chondroitin sulphate was effective for the treatment of radiotherapy- or chemotherapy-associated cystitis. Even short-term treatment appears to be effective in reducing symptoms and improving the quality of life of patients.

Use of a prospective cohort study in the development of a bladder scanning protocol to assist in bladder filling consistency for prostate cancer patients receiving radiation therapy

INTRODUCTION

Evidence of variations in bladder filling effecting prostate stability and therefore treatment and side-effects is well established with intensity modulated radiation therapy (IMRT). This study aimed to increase bladder volume reproducibility for prostate radiation therapy by implementing a bladder scanning (BS) protocol that could assist patients' bladder filling at computed tomography (CT) simulation and treatment.

METHODS

Based on a retrospective review of 524 prostate cancer patients, a bladder volume of 250-350 mL was adopted as 'ideal' for achieving planning dose constraints. A prospective cohort study was conducted to assess the clinical utility of measuring patients' bladder volumes at CT simulation using an ultrasound bladder scanner (Verathon 9400 BladderScan(®)). A revised bladder preparation protocol was utilised by a bladder scan group (BS) and a non-BS group followed the standard departmental bladder preparation protocol. Time and volume data for the BS group (n = 17) were compared with the non-BS group (n = 17).

RESULTS

The BS cohort had a CT bladder volume range of 221-588 mL; mean 379 mL, SD 125 mL. The non-BS group had a larger range: 184-757 mL; mean 373 mL, SD 160 mL (P = 0.9171). There was a positive correlation between CT volume and BS volume in the BS group (r = 0.797; P = 0.0002) although BS volumes were smaller: range 160-420 mL; mean 251 mL; SD 91 mL; P < 0.0001). The maximum bladder volume receiving 50 Gy (V50) from the BS group was 46.4%, mean 24.5%. The maximum bladder V50 from the non-BS group was 50.9%, mean 27.3% (P = 0.5178). Treatment data from weekly cone beam CT scans were also compared over 6 weeks. They were assessed as being a pass if bladder and bowel requirements were acceptable. The BS group proceeded to treatment on the basis of a pass 92.7% of the time, whereas the pass rate for non-BS group was 75%; difference 17.7% (P < 0.0001).

CONCLUSION

The BS is a useful tool for achieving consistent, appropriately sized bladder volumes in prostate cancer patients.

Emerging nanomedicine approaches fighting tumor metastasis: animal models, metastasis-targeted drug delivery, phototherapy, and immunotherapy

Nanomedicine approaches may bring new opportunities for tumor metastasis treatment.

The curative management of synchronous rectal and prostate cancer

OBJECTIVE

Neoadjuvant "long-course" chemoradiation is considered a standard of care in locally advanced rectal cancer. In addition to prostatectomy, external beam radiotherapy and brachytherapy with or without androgen suppression (AS) are well established in prostate cancer management. A retrospective review of ten cases was completed to explore the feasibility and safety of applying these standards in patients with dual pathology. To our knowledge, this is the largest case series of synchronous rectal and prostate cancers treated with curative intent.

METHODS

Eligible patients had synchronous histologically proven locally advanced rectal cancer (defined as cT3-4Nx; cTxN1-2) and non-metastatic prostate cancer (pelvic nodal disease permissible). Curative treatment was delivered to both sites simultaneously. Follow-up was as per institutional guidelines. Acute and late toxicities were reviewed, and a literature search performed.

RESULTS

Pelvic external beam radiotherapy (RT) 45-50.4 Gy was delivered concurrent with 5-fluorouracil (5FU). Prostate total dose ranged from 70.0 to 79.2 Gy. No acute toxicities occurred, excluding AS-induced erectile dysfunction. Nine patients proceeded to surgery, and one was managed expectantly. Three relapsed with metastatic colorectal cancer, two with metastatic prostate cancer. Five patients have no evidence of recurrence, and four remain alive with metastatic disease. With a median follow-up of 2.2 years (range 1.2-6.3 years), two significant late toxicities occurred; G3 proctitis in a patient receiving palliative bevacizumab and a G3 anastomotic stricture precluding stoma reversal.

CONCLUSION

Patients proceeding to synchronous radical treatment of both primary sites should receive 45-50.4 Gy pelvic RT with infusional 5FU. Prostate dose escalation should be given with due consideration to the potential impact of prostate cancer on patient survival, as increasing dose may result in significant late morbidity. Review of published series explores the possibility of prostate brachytherapy as an alternative method of boost delivery. Frequent use of bevacizumab in metastatic rectal cancer may compound late rectal morbidity in this cohort.

ADVANCES IN KNOWLEDGE

To our knowledge, this is the largest case series of synchronous rectal and prostate cancers treated with curative intent. This article contributes to the understanding of how best to approach definitive treatment in these patients.

Functional Radiotherapy Targeting using Focused Dose Escalation

Various quantitative and semi-quantitative imaging biomarkers have been identified that may serve as valid surrogates for the risk of recurrence after radiotherapy. Tumour characteristics, such as hypoxia, vascularity, cellular proliferation and clonogen density, can be geographically mapped using biological imaging techniques. The potential gains in therapeutic ratio from the precision targeting of areas of intrinsic resistance makes focused dose escalation an exciting field of study. This overview will explore the issues surrounding biologically optimised radiotherapy, including its requirements, feasibility, technical considerations and potential applicability.

Accumulated dose to the rectum, measured using dose-volume histograms and dose-surface maps, is different from planned dose in all patients treated with radiotherapy for prostate cancer

OBJECTIVE

We sought to calculate accumulated dose (DA) to the rectum in patients treated with radiotherapy for prostate cancer. We were particularly interested in whether dose-surface maps (DSMs) provide additional information to dose-volume histograms (DVHs).

METHODS

Manual rectal contours were obtained for kilovoltage and daily megavoltage CT scans for 10 participants from the VoxTox study (380 scans). Daily delivered dose recalculation was performed using a ray-tracing algorithm. Delivered DVHs were summated to create accumulated DVHs. The rectum was considered as a cylinder, cut and unfolded to produce daily delivered DSMs; these were summated to produce accumulated DSMs.

RESULTS

Accumulated dose-volumes were different from planned in all participants. For one participant, all DA levels were higher and all volumes were larger than planned. For four participants, all DA levels were lower and all volumes were smaller than planned. For each of these four participants, ≥1% of pixels on the accumulated DSM received ≥5 Gy more than had been planned.

CONCLUSION

Differences between accumulated and planned dose-volumes were seen in all participants. DSMs were able to identify differences between DA and planned dose that could not be appreciated from the DVHs. Further work is needed to extract the dose data embedded in the DSMs. These will be correlated with toxicity as part of the VoxTox Programme.

ADVANCES IN KNOWLEDGE

DSMs are able to identify differences between DA and planned dose that cannot be appreciated from DVHs alone and should be incorporated into future studies investigating links between DA and toxicity.

Hypofractionated Helical Tomotherapy for Older Aged Patients With Prostate Cancer: Preliminary Results of a Phase I-II Trial

In our center, the feasibility and related acute toxicities of hypofractionated helical tomotherapy have been evaluated in older aged patients with prostate cancer . Between February 2009 and February 2014, 67 patients (older than 65 years) were enrolled in a prospective phase I-II study (registered number, ChiCTR-ONC-13004037). Patients in cohort 1 (n = 33) and cohort 2 (n = 34) received 76 Gy in 34 fractions (2.25 Gy/F) and 71.6 Gy in 28 fractions (2.65 Gy/F), respectively, to the prostate and seminal vesicles, while 25 patients in cohort 2 also received integrated elective lymph node irradiation (50.4 Gy). All patients were treated with helical tomotherapy, and daily image guidance was performed before each treatment. Acute toxicities were assessed with Radiation Therapy Oncology Group (RTOG)/European Organization for Research on Treatment of Cancer (EORTC) criteria. No significant difference was detected between the 2 cohorts in the incidence of acute toxicities. In cohort 1, the incidences of grade 1 and 2 genitourinary and gastrointestinal toxicities were 45.5% and 45.4%, respectively, and without grade 3 and 4 toxicities. In cohort 2, the incidences of acute grade 1 and 2 genitourinary and gastrointestinal toxicities were 47.1% and 55.9%, respectively, and grade 3 genitourinary toxicity (hematuria) was noted only in 1 patient. No significant difference was detected in the incidence of acute toxicities between the patients receiving integrated elective lymph node irradiation and those receiving irradiation to prostate and seminal vesicle in cohort 2. Univariate and multivariate analyses were performed with clinical parameters. Only the baseline weight was found negatively correlated with genitourinary toxicities at a weak level (relative risk = 0.946, 95% confidence interval 0.896-0.998], P = .043). This study shows that 2 hypofractionation regimens (76 Gy/34F and 71.6 Gy/28F) delivered with HT are well tolerated in older aged patients having prostate cancer without significant difference for acute toxicities between the 2 cohorts. Late toxicities and treatment outcomes for these patients are under investigation.

Analysis of Prostate Deformation during a Course of Radiation Therapy for Prostate Cancer

PURPOSE

Accurate analysis of the correlation between deformation of the prostate and displacement of its center of gravity (CoG) is important for efficient radiation therapy for prostate cancer. In this study, we addressed this problem by introducing a new analysis approach.

METHOD

A planning computed tomography (CT) scan and 7 repeat cone-beam CT scans during the course of treatment were obtained for 19 prostate cancer patients who underwent three-dimensional conformal radiation therapy. A single observer contoured the prostate gland only. To evaluate the local deformation of the prostate, it was divided into 12 manually defined segments. Prostate deformation was calculated using in-house developed software. The correlation between the displacement of the CoG and the local deformation of the prostate was evaluated using multiple regression analysis.

RESULTS

The mean value and standard deviation (SD) of the prostate deformation were 0.6 mm and 1.7 mm, respectively. For the majority of the patients, the local SD of the deformation was slightly lager in the superior and inferior segments. Multiple regression analysis revealed that the anterior-posterior displacement of the CoG of the prostate had a highly significant correlation with the deformations in the middle-anterior (p < 0.01) and middle-posterior (p < 0.01) segments of the prostate surface (R2 = 0.84). However, there was no significant correlation between the displacement of the CoG and the deformation of the prostate surface in other segments.

CONCLUSION

Anterior-posterior displacement of the CoG of the prostate is highly correlated with deformation in its middle-anterior and posterior segments. In the radiation therapy for prostate cancer, it is necessary to optimize the internal margin for every position of the prostate measured using image-guided radiation therapy.

Ion therapy of prostate cancer: daily rectal dose reduction by application of spacer gel

Background

Ion beam therapy represents a promising approach to treat prostate cancer, mainly due to its high conformity and radiobiological effectiveness. However, the presence of prostate motion, patient positioning and range uncertainties may deteriorate target dose and increase exposure of organs at risk. Spacer gel injected between prostate and rectum may increase the safety of prostate cancer (PC) radiation therapy by separating the rectum from the target dose field. The dosimetric impact of the application of spacer gel for scanned carbon ion therapy of PC has been analyzed at Heidelberg Ion-Beam Therapy Center (HIT).

Materials and methods

The robustness of ion therapy treatment plans was investigated by comparison of two data sets of patients treated with and without spacer gel. A research treatment planning system for ion therapy was used for treatment plan optimization and calculation of daily dose distributions on 2 to 9 Computed Tomography (CT) studies available for each of the 19 patients. Planning and daily dose distributions were analyzed with respect to target coverage, maximal dose to the rectum (excluding 1 ml of the greatest dose; Dmax-1 ml) and the rectal volume receiving dose greater than 90% of prescribed target dose (V90_Rectum), respectively.

Results

The application of spacer gel did substantially diminish rectum dose. Dmax-1 ml on the treatment planning CT was on average reduced from 100.0 ± 1.0% to 90.2 ± 4.8%, when spacer gel was applied. The robustness analysis performed with daily CT studies demonstrated for all analyzed patient cases that application of spacer gel results in a decrease of the daily V90_Rectum index, which calculated over all patient cases and CT studies was 10.2 ± 10.4 [ml] and 1.1 ± 2.1 [ml] for patients without and with spacer gel, respectively.

Conclusions

The dosimetric benefit of increasing the distance between prostate and rectum using spacer gel for PC treatment with carbon ion beams has been quantified. Application of spacer gel substantially reduced rectal exposure to high treatment dose and, therefore, can reduce the hazard of rectal toxicity in ion beam therapy of PC. The results of this study enable modifications of the PC ion therapy protocol such as dose escalation or hypofractionation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-015-0348-1) contains supplementary material, which is available to authorized users.

Dosimetric analysis of urethral strictures following HDR (192)Ir brachytherapy as monotherapy for intermediate- and high-risk prostate cancer

BACKGROUND AND PURPOSE

To evaluate dosimetric parameters related to urethral strictures following high dose-rate brachytherapy (HDRBT) alone for prostate cancer.

MATERIAL AND METHODS

Ten strictures were identified in 213 patients treated with HDRBT alone receiving 34Gy in four fractions, 36Gy in four fractions, 31.5Gy in 3 fractions or 26Gy in 2 fractions. A matched-pair analysis used 2 controls for each case matched for dose fractionation schedule, pre-treatment IPSS score, number of needles used and clinical target volume. The urethra was divided into membranous urethra and inferior, mid and superior thirds of the prostatic urethra.

RESULTS

Stricture rates were 3% in the 34Gy group, 4% in the 36Gy group, 6% in the 31.5Gy group and 4% in the 26Gy group. The median time to stricture formation was 26months (range 8-40). The dosimetric parameters investigated were not statistically different between cases and controls. No correlation was seen between stricture rate and fractionation schedule.

CONCLUSIONS

Urethral stricture is an infrequent complication of prostate HDRBT when used to deliver high doses as sole treatment, with an overall incidence in this cohort of 10/213 (4.7%). In a matched pair analysis no association with dose schedule or urethral dosimetry was identified, but the small number of events limits definitive conclusions.

Calculation of planning margins for different verification techniques in radical prostate radiotherapy

Purpose

To calculate and compare planning target volume (PTV) margins for an offline 3 mm tolerance, daily bony anatomy verification, tattoo alignment and online prostate marker matching with those currently used at our institution.

Methods

Seventy patients had offline bony anatomy megavoltage verification. 23 different patients underwent fiducial marker matching using daily online kilovoltage verification. Systematic and random errors were measured in the right–left (RL), superior–inferior (SI) and anterior–posterior (AP) directions. Geometric uncertainties from literature were used to help calculate the margins.

Results

PTV margins (mm) were 7 RL, 12 SI and AP (3 mm tolerance offline bony), 6 RL, 11 SI and AP (daily online bony), 8 RL, 12 SI and AP (tattoo alignment) and 5 RL, 8 SI and 6 AP (online daily prostate marker correction).

Conclusions

Our current margins for conformal radiotherapy patients are too small for phase 2 in the SI and AP directions. Implementing online daily bony anatomy matching would not reduce the PTV margin significantly. Online daily marker correction showed current PTV71 Gy margins as excessive by (mm) 5 RL, 2 SI and 4 anterior.

Comparative efficacy and safety of treatments for localised prostate cancer: an application of network meta-analysis

CONTEXT

There is ongoing uncertainty about the optimal management of patients with localised prostate cancer.

OBJECTIVE

To evaluate the comparative efficacy and safety of different treatments for patients with localised prostate cancer.

DESIGN

Systematic review with Bayesian network meta-analysis to estimate comparative ORs, and a score (0-100%) that, for a given outcome, reflects average rank order of superiority of each treatment compared against all others, using the Surface Under the Cumulative RAnking curve (SUCRA) statistic.

DATA SOURCES

Electronic searches of MEDLINE without language restriction.

STUDY SELECTION

Randomised trials comparing the efficacy and safety of different primary treatments (48 papers from 21 randomised trials included 7350 men).

DATA EXTRACTION

2 reviewers independently extracted data and assessed risk of bias.

RESULTS

Comparative efficacy and safety evidence was available for prostatectomy, external beam radiotherapy (different types and regimens), observational management and cryotherapy, but not high-intensity focused ultrasound. There was no evidence of superiority for any of the compared treatments in respect of all-cause mortality after 5 years. Cryotherapy was associated with less gastrointestinal and genitourinary toxicity than radiotherapy (SUCRA: 99% and 77% for gastrointestinal and genitourinary toxicity, respectively).

CONCLUSIONS

The limited available evidence suggests that different treatments may be optimal for different efficacy and safety outcomes. These findings highlight the importance of informed patient choice and shared decision-making about treatment modality and acceptable trade-offs between different outcomes. More trial evidence is required to reduce uncertainty. Network meta-analysis may be useful to optimise the power of evidence synthesis studies once data from new randomised controlled studies in this field are published in the future.

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.

Effect on therapeutic ratio of planning a boosted radiotherapy dose to the dominant intraprostatic tumour lesion within the prostate based on multifunctional MR parameters

OBJECTIVE

To demonstrate the feasibility of an 8-Gy focal radiation boost to a dominant intraprostatic lesion (DIL), identified using multiparametric MRI (mpMRI), and to assess the potential outcome compared with a uniform 74-Gy prostate dose.

METHODS

The DIL location was predicted in 23 patients using a histopathologically verified model combining diffusion-weighted imaging, dynamic contrast-enhanced imaging, T2 maps and three-dimensional MR spectroscopic imaging. The DIL defined prior to neoadjuvant hormone downregulation was firstly registered to MRI-acquired post-hormone therapy and subsequently to CT radiotherapy scans. Intensity-modulated radiotherapy (IMRT) treatment was planned for an 8-Gy focal boost with 74-Gy dose to the remaining prostate. Areas under the dose-volume histograms (DVHs) for prostate, bladder and rectum, the tumour control probability (TCP) and normal tissue complication probabilities (NTCPs) were compared with those of the uniform 74-Gy IMRT plan.

RESULTS

Deliverable IMRT plans were feasible for all patients with identifiable DILs (20/23). Areas under the DVHs were increased for the prostate (75.1 ± 0.6 vs 72.7 ± 0.3 Gy; p < 0.001) and decreased for the rectum (38.2 ± 2.5 vs 43.5 ± 2.5 Gy; p < 0.001) and the bladder (29.1 ± 9.0 vs 36.9 ± 9.3 Gy; p < 0.001) for the boosted plan. The prostate TCP was increased (80.1 ± 1.3 vs 75.3 ± 0.9 Gy; p < 0.001) and rectal NTCP lowered (3.84 ± 3.65 vs 9.70 ± 5.68 Gy; p = 0.04) in the boosted plan. The bladder NTCP was negligible for both plans.

CONCLUSION

Delivery of a focal boost to an mpMRI-defined DIL is feasible, and significant increases in TCP and therapeutic ratio were found.

ADVANCES IN KNOWLEDGE

The delivery of a focal boost to an mpMRI-defined DIL demonstrates statistically significant increases in TCP and therapeutic ratio.

Detection of prostate calcification with megavoltage helical CT

RATIONALE AND OBJECTIVES

Prostate calcification is a noninvasive landmark for daily positioning of image-guided radiation therapy. However, detectability of prostate calcification with megavoltage helical computed tomography (MVCT) has not been evaluated. The purpose of this study was to evaluate the detectability of prostate calcification and to investigate how to predict detectability of calcification with MVCT.

MATERIALS AND METHODS

Thirty patients with prostate cancer who were scheduled for helical tomotherapy were included in this study. The detectability of prostate calcification on MVCT was evaluated by comparing against kilovoltage multidetector-row CT (KVCT) as the standard of reference. Maximum signal intensity (SImax), area (A) of calcification, and the product of both (SImax·A) were compared between undetectable and detectable calcifications. Then, the threshold values of SImax, A, and SImax·A were decided to achieve 100% sensitivity on MVCT.

RESULTS

KVCT identified 49 calcifications in 28 of 30 patients. MVCT detected 19 (39%) of 49 calcifications in 15 (50%) of 30 patients. The minimum threshold values of SImax, A, and SImax·A to detect prostate calcifications were 953 HU, 20.98 mm(2), and 7784 HU mm(2), respectively. Using the threshold values of SImax, A, and SImax·A, 20% (10/49), 18% (9/49), and 35% (17/49) of calcifications were in the detection range, respectively.

CONCLUSIONS

MVCT can depict about one-third of prostate calcifications detectable on KVCT. The product of maximum signal intensity and area of calcification is the most distinguishable index for predicting patients showing prostate calcifications on MVCT.

Hypofractionation in prostate cancer: radiobiological basis and clinical appliance

External beam radiation therapy with conventional fractionation to a total dose of 76–80 Gy represents the most adopted treatment modality for prostate cancer. Dose escalation in this setting has been demonstrated to improve biochemical control with acceptable toxicity using contemporary radiotherapy techniques. Hypofractionated radiotherapy and stereotactic body radiation therapy have gained an increasing interest in recent years and they have the potential to become the standard of care even if long-term data about their efficacy and safety are not well established. Strong radiobiological basis supports the use of high dose for fraction in prostate cancer, due to the demonstrated exceptionally low values of α/β. Clinical experiences with hypofractionated and stereotactic radiotherapy (with an adequate biologically equivalent dose) demonstrated good tolerance, a PSA control comparable to conventional fractionation, and the advantage of shorter time period of treatment. This paper reviews the radiobiological findings that have led to the increasing use of hypofractionation in the management of prostate cancer and briefly analyzes the clinical experience in this setting.

Prognostic factors for newly diagnosed prostate cancer and their role in treatment selection

Adenocarcinoma of the prostate is extremely heterogeneous, ranging from an indolent chronic illness to an aggressive rapidly fatal systemic malignancy. The classic prognostic factors of tumor stage, prostate specific antigen level, and Gleason score have been used for over a decade to categorize patients at the time of diagnosis into broad risk groups that help to determine appropriate management. Although the grouping of patients into favorable, intermediate, and high-risk categories has become standard, and the categories continue to define distinct prognostic subgroups, considerable heterogeneity exists within each risk group. As a range of management options are available, additional prognostic factors can be considered when determining the treatment approach for an individual patient. We review these additional prognostic variables under the headings of patient-related, tumor-related, and treatment-related. The influence of each of these factors may vary depending on treatment factors such as dose, the radiation modality, or the use of concomitant androgen ablation.

Assessment of interfractional prostate motion in patients immobilized in the prone position using a thermoplastic shell

The aim of this study was to evaluate the interfractional prostate motion of patients immobilized in the prone position using a thermoplastic shell. A total of 24 patients with prostate calcifications detectable using a kilo-voltage X-ray image-guidance system (ExacTrac X-ray system) were examined. Daily displacements of the calcification within the prostate relative to pelvic bony structures were calculated by the ExacTrac X-ray system. The average displacement and standard deviation (SD) in each of the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were calculated for each patient. Based on the results of interfractional prostate motion, we also calculated planning target volume (PTV) margins using the van Herk formula and examined the validity of the PTV margin of our institute (a 9-mm margin everywhere except posteriorly, where a 6-mm margin was applied). In total, 899 data measurements from 24 patients were obtained. The average prostate displacements ± SD relative to bony structures were 2.8 ± 3.3, -2.0 ± 2.0 and 0.2 ± 0.4 mm, in the SI, AP and LR directions, respectively. The required PTV margins were 9.7, 6.1 and 1.4 mm in the SI, AP and LR directions, respectively. The clinical target volumes of 21 patients (87.5%) were located within the PTV for 90% or more of all treatment sessions. Interfractional prostate motion in the prone position with a thermoplastic shell was equivalent to that reported for the supine position. The PTV margin of our institute is considered appropriate for alignment, based on bony structures.

Optimal Local Control and Tolerability of Three-Dimensional Conformal Radiation Therapy in Prostate Cancer: A Single Institutional Experience of Dose Escalation in 125 Patients

Aims

To evaluate long-term late side effects, clinical and biochemical relapse in non-metastatic prostate cancer patients treated with dose escalation, from 74 to 78 Gy, by means of three dimensional conformal radiation therapy.

Materials and Methods

Clinical data of 125 patients with prostate cancer who underwent three-dimensional conformal radiation therapy were retrospectively evaluated. All patients were stratified, according to the NCCN classification, in low, intermediate and high risk, and all of them showed histologically proven adenocarcinoma stage T1–T3 with at least 2 years of follow-up. Late toxicity was analyzed using a modified Radiation Therapy Oncology Group toxicity scale.

Results

With a median of follow-up of 48 months, grade ≥2 late genitourinary toxicity was reported in 18% and grade ≥2 gastrointestinal toxicity was detected in 12%. The PSA relapse rate was 20% in the high-risk group, 7% in the intermediate-risk group, and 3% in the low-risk group.

Conclusions

Late side effects and tumor control in patients with non-metastatic prostate cancer in dose escalation from 74 to 78 Gy was acceptable. Three-dimensional conformal radiation therapy still represents a valid therapeutic option for departments where intensity-modulated radiation therapy or image-guided radiation therapy is still not available.

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

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

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

Combination therapy with the histone deacetylase inhibitor LBH589 and radiation is an effective regimen for prostate cancer cells

Radiation therapy (RT) continues to be one of the most popular treatment options for localized prostate cancer (CaP). The purpose of the study was to investigate the in vitro effect of LBH589 alone and in combination with RT on the growth and survival of CaP cell lines and the possible mechanisms of radiosensitization of this combination therapy. The effect of LBH589 alone or in combination with RT on two CaP cell lines (PC-3 and LNCaP) and a normal prostatic epithelial cell line (RWPE-1) was studied by MTT and clonogenic assays, cell cycle analysis, western blotting of apoptosis-related and cell check point proteins, and DNA double strand break (DSB) repair markers. The immunofluorescence staining was used to further confirm DSB expression in treated CaP cells. Our results indicate that LBH589 inhibited proliferation in both CaP and normal prostatic epithelial cells in a time-and-dose-dependent manner; low-dose of LBH589 (IC₂₀) combined with RT greatly improved efficiency of cell killing in CaP cells; compared to RT alone, the combination treatment with LBH589 and RT induced more apoptosis and led to a steady increase of sub-G1 population and abolishment of RT-induced G2/M arrest, increased and persistent DSB, less activation of non-homologous end joining (NHEJ)/homologous recombination (HR) repair pathways and a panel of cell cycle related proteins. These results suggest that LBH589 is a potential agent to increase radiosensitivity of human CaP cells. LBH589 used either alone, or in combination with RT is an attractive strategy for treating human CaP.

Randomised pilot study of dose escalation using conformal radiotherapy in prostate cancer: long-term follow-up

BACKGROUND

Radical three-dimensional conformal radiotherapy (CFRT) with initial androgen suppression (AS) is a standard management for localised prostate cancer (PC). This pilot study evaluated the role of dose escalation and appropriate target volume margin. Here, we report long-term follow-up.

METHODS

Eligible patients had T1b-T3b N0 M0 PC. After neoadjuvant AS, they were randomised to CFRT, giving (a) 64 Gy with either a 1.0- or 1.5-cm margin and (b) ±10 Gy boost to the prostate alone.

RESULTS

One hundred and twenty-six men were randomised and treated. Median follow-up was 13.7 years. The median age was 66.6 years at randomisation. Median presenting prostate-specific antigen (PSA) was 14 ng ml(-1). Sixty-four out of 126 patients developed PSA failure. Forty-nine out of 126 patients restarted AS, 34 out of 126 developed metastases and 28 out of 126 developed castrate-resistant prostate cancer (CRPC). Fifty-one out of 126 patients died; 19 out of 51 died of PC. Median overall survival (OS) was 14.4 years. Although escalated dose results were favourable, no statistically significant differences were seen between the randomised groups; PSA control (hazard ratio (HR): 0.77 (95% confidence interval (CI): 0.47-1.26)), development of CRPC (HR: 0.81 (95% CI: 0.40-1.65)), PC-specific survival (HR: 0.59 (95% CI:0.23-1.49)) and OS (HR: 0.81 (95% CI: 0.47-1.40)). There was no evidence of a difference in PSA control according to margin size (HR: 1.01 (95% CI: 0.61-1.66)).

INTERPRETATION

Long-term follow-up of this small pilot study is compatible with a benefit from dose escalation, but confirmation from larger trials is required. There was no obvious detriment using the smaller radiotherapy margin.

Preclinical investigations towards the first spacer gel application in prostate cancer treatment during particle therapy at HIT

Background

The application of spacer gel represents a promising approach to reliably spare the rectal frontal wall during particle therapy (IJROBP 76:1251-1258, 2010). In order to qualify the spacer gel for the clinical use in particle therapy, a variety of measurements were performed in order to ensure the biological compatibility of the gel, its physical stability during and after the irradiation, and a proper definition of the gel in terms of the Hounsfield Unit (HU) values for the treatment planning system. The potential for the use of the spacer gel for particle therapy monitoring with off-line Positron Emission Tomography (PET) was also investigated.

Results

The spacer gel implanted to the prostate patient in direct neighbourhood to the clinical target volume does not interfere with the particle therapy treatment planning procedure applied at Heidelberg Ion Beam Therapy Centre (HIT). The performed measurements show that Bragg-peak position of the particles can be properly predicted on the basis of computed tomography imaging with the treatment planning system used at HIT (measured water equivalent path length of 1.011 ±0.011 (2σ), measured Hounsfield Unit of 28.9 ±6.1 (2σ)). The spacer gel samples remain physically unchanged after irradiation with a dose exceeding the therapeutic dose level. The independently measured Bragg-Peak position does not change within the time interval of 10 weeks.

Conclusions

As a result of the presented experiments, the first clinical application of spacer gel implant during prostate cancer treatment with carbon ions and protons was possible at HIT in 2012. The reported pre-clinical investigations demonstrate that use of spacer gel is safe in particle therapy in presence of therapy target motion and patient positioning induced particle range variations. The spacer gel injected between prostate and rectum enlarge the distance between both organs, which is expected to clinically significantly decrease the undesirable exposure of the most critical organ at risk, i.e. rectal frontal wall. Further research on the composition of spacer gel material might lead to additional clinical benefits by validation of particle therapy of prostate via post-therapeutic PET-imaging or by patient positioning based on the gel as a radio-opaque marker.

Mortality after radical prostatectomy or external beam radiotherapy for localized prostate cancer

BACKGROUND

No randomized trials have compared survival outcomes for men with localized prostate cancer (PC) being treated with radical prostatectomy (RP) or external beam radiotherapy (EBRT). The goal of the study, therefore, was to estimate the association of RP (compared with EBRT) with overall and PC mortality.

METHODS

We analyzed an observational cohort from the population-based Prostate Cancer Outcomes Study, which included men aged 55 to 74 years diagnosed with localized PC between October 1994 and October 1995 who underwent either RP (n = 1164) or EBRT (n = 491) within 1 year of diagnosis. Patients were followed until death or study end (December 31, 2010). Overall and disease-specific mortality were assessed with multivariable survival analysis, with propensity scores to adjust for potential treatment selection confounders (demographics, comorbidities, and tumor characteristics). All statistical tests were two-sided.

RESULTS

After 15 years of follow-up, there were 568 deaths, including 104 from PC. RP was associated with statistically significant advantages for overall (hazard ratio [HR] = 0.60, 95% confidence interval [CI] = 0.53 to 0.70, P <.0001.) and disease-specific mortality (HR = 0.35, 95% CI = 0.26 to 0.49, P <.0001.). Mortality benefits for RP were also observed within treatment propensity quintiles, when subjects were pair-matched on propensity scores, and in subgroup analyses based on age, tumor characteristics, and comorbidity.

CONCLUSIONS

Population-based observational data on men diagnosed with localized PC in the mid-1990s suggest a mortality benefit associated with RP vs EBRT. Possible explanations include residual selection bias or a true survival advantage. Results might be less applicable for men facing treatment decisions today.