Prostate cancer radiation dose response: results of the M. D. Anderson phase III randomized trial

Quantitative Evaluation of the Benefit of Fiducial Image-Guidance for Prostate Cancer Intensity Modulated Radiation Therapy Using Daily Dose Volume Histogram Analysis

To quantitatively evaluate the extent to which fiducial-based image-guidance improves dose coverage of the target volume and sparing of critical organs for prostate cancer patients treated with intensity modulated radiotherapy (IMRT) and determination of planning margins by original approach of detailed daily dose volume histogram (DVH) and patient's position correction analysis. Sixty-two patients divided in two groups (clinical target volume (CTV) → planning target volume (PTV) margin 10 and 7 mm) were treated with IMRT using implanted fiducial markers. Each patient's treatment fraction was recalculated as it would have been treated without fiducial-guided positioning. For both plans (IGRT and non-IGRT), equivalent uniform doses (EUD), maximal and minimal doses for target volumes, normal tissue complication probability (NTCP), maximum and mean doses for organs at risk and the whole DVH differences were assessed. In the group with 10 mm margins, the only significant difference was worse rectal NTCP by 4.5%, but the CTV dose coverage remained at the same level. Recalculated plans with 7 mm margin could not achieve the prescribed target volume coverage, and the EUD decreased by 3.7 and 0.6 Gy for PTV and CTV, respectively. Desired CTV → PTV margin for non-IGRT plans should be no lower than 12 mm to guarantee 95% instances when delivered dose to CTV maintain as planned, for IGRT plans decrease this requirement to 2 mm. Prostate IMRT strategies involving margin reduction below 7 mm require image-guidance to maintain the planned dose coverage. Using fiducial-based image-guidance and large margins seems to be superfluous.

Dosimetric effect of Elekta Beam modulator micromultileaf in three-dimensional conformal radiotherapy and intensity-modulated radiotherapy for prostate cancer

The purpose of this study is to analyze the dosimetric effect of Elekta Beam Modulator in 3-dimensional conformal radiation therapy (3DCRT) and in intensity-modulated radiation therapy (IMRT) for localized prostate cancer. We compared treatment plans developed with 2 different Elekta multileaf collimators (MLC): Beam Modulator micro-MLC (mMLC) (4-mm leaf width at the isocenter) and standard MLC (10-mm leaf width at the isocenter). The comparison was performed for 15 patients with localized prostate cancer in 3DCRT and IMRT delivery; a total of 60 treatment plans were processed. The dose-volume histograms were used to provide the quantitative comparison between plans. In particular, we analyzed differences between rectum and bladder sparing in terms of a set of appropriate Vx (percentage of organ at risk [OAR] volume receiving the x dose) and differences between target conformity and coverage in terms of coverage factor and conformation number. Our analysis demonstrates that in 3DCRT there is an advantage in the use of Elekta Beam Modulator mMLC in terms of organ sparing; in particular, a significant decrease in rectal V60 and V50 (p = 0.001) and in bladder V70 and V65 (p = 0.007 and 0.002, respectively) was found. Moreover, a better target dose conformity was obtained (p = 0.002). IMRT plans comparison demonstrated no significant differences between the use of the 4 or 10-mm MLCs. Our analysis shows that in 3DCRT the use of the Elekta Beam Modulator mMLC gives a gain in target conformity and in OARs dose sparing whereas in IMRT plans there is no advantage.

A study on planning organ at risk volume for the rectum using cone beam computed tomography in the treatment of prostate cancer

In this study, we analyzed planning organ at risk volume (PRV) for the rectum using a series of cone beam computed tomographies (CBCTs) acquired during the treatment of prostate cancer and evaluated the dosimetric effect of different PRV definitions. Overall, 21 patients with prostate cancer were treated radically with 78Gy in 39 fractions had in total 418 CBCTs, each acquired at the end of the first 5 fractions and then every alternate fraction. The PRV was generated from the Boolean sum volume of the rectum obtained from first 5 fractions (PRV-CBCT-5) and from all CBCTs (PRV-CBCT-All). The PRV margin was compared at the superior, middle, and inferior slices of the contoured rectum to compare PRV-CBCT-5 and PRV-CBCT-All. We also compared the dose received by the planned rectum (Rectum-computed tomography [CT]), PRV-CBCT-5, PRV-CBCT-All, and average rectum (CBCT-AV-dose-volume histogram [DVH]) at critical dose levels. The average measured rectal volume for all 21 patients for Rectum-CT, PRV-CBCT-5, and PRV-CBCT-All was 44.3 ± 15.0, 92.8 ± 40.40, and 121.5 ± 36.7cm(3), respectively. For PRV-CBCT-All, the mean ± standard deviation displacement in the anterior, posterior, right, and left lateral directions in centimeters was 2.1 ± 1.1, 0.9 ± 0.5, 0.9 ± 0.8, and 1.1 ± 0.7 for the superior rectum; 0.8 ± 0.5, 1.1 ± 0.5, 1.0 ± 0.5, and 1.0 ± 0.5 for the middle rectum; and 0.3 ± 0.3; 0.9 ± 0.5; 0.4 ± 0.2, and 0.5 ± 0.3 for the inferior rectum, respectively. The first 5 CBCTs did not predict the PRV for individual patients. Our study shows that the PRV margin is different for superior, middle, and the inferior parts of the rectum, it is wider superiorly and narrower inferiorly. A uniform PRV margin does not represent the actual rectal variations during treatment for all treatment fractions. The large variation in interpatient rectal size implies a potential role for adaptive radiotherapy for prostate cancer.

Early Outcome of Prostate Intensity Modulated Radiation Therapy (IMRT) Incorporating a Simultaneous Intra-Prostatic MRI Directed Boost

This study assessed the feasibility and outcomes of treating prostate cancer with intensity modulated radiotherapy (IMRT) incorporating a Magnetic Resonance Imaging (MRI) directed boost. Seventy-eight men received IMRT for localized prostate cancer. The entire prostate received 77.4Gy in 43 fractions and simultaneous intra-prostatic boosts (SIB) of 83Gy were administered to increase the dose to the MRI identified malignancy. In 16 (21%) patients, the MRI didn't detect a neoplasm and these patients received an SIB of 81Gy to the posterior prostate. Androgen Deprivation Therapy (ADT) was also administered to 32 (41%) patients. The 3-year rates of biochemical control, local control, distant control, and survival were 92%, 98%, 95%, and 95% respectively. While grade 1-2 toxicities were common, there were only 2 patients who suffered grade 3 toxicity. These patients developed strictures which were dilated resulting in improvement in symptoms such that both had grade 1-2 toxicity at last follow up examination. The results of this program of IMRT incorporating a MRI directed intra-prostatic boost suggest this technique is feasible and well tolerated. This technique appears to shift the therapeutic index favorably by boosting the malignancy to the highest dose without increasing the doses administered to the bladder and rectum.

Reduction in radiation-induced lymphocytopenia by famotidine in patients undergoing radiotherapy for prostate cancer

BACKGROUND

Ionizing radiation causes a series of hematological alterations especially profound lymphocytopenia during and after the radiotherapy course. To investigate whether famotidine can reduce hematologic toxicity in patients treated with radiotherapy for prostate cancer.

METHODS

A total of 36 patients undergoing radiotherapy for prostate cancer were randomized to receive either placebo or famotidine tablets. Participants were pretreated with 40 mg of oral famotidine or placebo tablets twice daily, 4 and 3 hr before each radiotherapy fraction. The patients received external-beam radiotherapy up to 70 Gy. Complete blood counts with differential, platelet counts, and hemoglobin levels were obtained at baseline, biweekly during the treatment and once 4 weeks after the end of radiotherapy course. Magnitude of changes from baseline in the hematological parameters was determined and compared using Repeated Measures ANOVA.

RESULTS

Famotidine was well tolerated. A total of 112 blood samples were evaluated. A significant reduction in radiation-induced lymphocytopenia was noted in patients receiving famotidine than in patients receiving placebo (P = 0.006). No significant difference was observed between two groups for the decline in platelets, erythrocytes and leucocytes. For both groups, neutrophil, monocyte, eosinophil, and hemoglobin levels did not change significantly during the treatment.

CONCLUSIONS

Our results indicate that famotidine could result in a significant reduction in radiation-induced lymphocytopenia and may consequently increase radiotherapy efficacy as well as survival times. This radioprotective effect may be chiefly associated with its antioxidant and radical scavenging properties. Further studies are required to confirm these encouraging results.

Whole pelvic intensity-modulated radiotherapy for high-risk prostate cancer: a preliminary report

Purpose

To assess the clinical efficacy and toxicity of whole pelvic intensity-modulated radiotherapy (WP-IMRT) for high-risk prostate cancer.

Materials and Methods

Patients with high-risk prostate cancer treated between 2008 and 2013 were reviewed. The study included patients who had undergone WP-IMRT with image guidance using electronic portal imaging devices and/or cone-beam computed tomography. The endorectal balloon was used in 93% of patients. Patients received either 46 Gy to the whole pelvis plus a boost of up to 76 Gy to the prostate in 2 Gy daily fractions, or 44 Gy to the whole pelvis plus a boost of up to 72.6 Gy to the prostate in 2.2 Gy fractions.

Results

The study cohort included 70 patients, of whom 55 (78%) had a Gleason score of 8 to 10 and 50 (71%) had a prostate-specific antigen level > 20 ng/mL. The androgen deprivation therapy was combined in 62 patients. The biochemical failure-free survival rate was 86.7% at 2 years. Acute any grade gastrointestinal (GI) and genitourinary (GU) toxicity rates were 47% and 73%, respectively. The actuarial rate of late grade 2 or worse toxicity at 2 years was 12.9% for GI, and 5.7% for GU with no late grade 4 toxicity.

Conclusion

WP-IMRT was well tolerated with no severe acute or late toxicities, resulting in at least similar biochemical control to that of the historic control group with a small field. The long-term efficacy and toxicity will be assessed in the future, and a prospective randomized trial is needed to verify these findings.

Outcomes of high-dose intensity-modulated radiotherapy alone with 1 cm planning target volume posterior margin for localized prostate cancer

Background

Clinically localized prostate cancer may be treated by different approaches of radiation therapy. The aim of this study was to report the results of disease control and toxicity in patients with clinically localized prostate cancer treated with high dose IMRT alone with 1 cm PTV posterior margin.

Methods

From September 2001 to April 2008, 140 patients with localized prostate cancer were treated with definitive IMRT (dose ≥ 74 Gy) without hormone therapy. Outcomes were measured from the conclusion of radiotherapy. Biochemical failure was defined as PSA nadir + 2.0 ng/dL. Toxicities were assessed using the NCI-CTCAE-version 3.0. Median follow-up was 58 months.

Results

Biochemical failure occurred in 13.6% of patients. Actuarial 5-year biochemical control rates were 91.7%, 82.5% and 85.9% for low-, intermediate-, and high-risk patients, respectively. Stage T2 patients presented a risk of biochemical failure almost three times higher than stage T1 (RR = 2.91; 95% CI: 1.04; 8.17). Distant metastases occurred in 3 (2%) patients. Five-year metastasis-free and overall survivals were 96% and 97.5%, respectively. Late grade 3 genitourinary and gastrointestinal toxicity rates were, respectively, 1.6% and 3%.

Conclusion

High-dose IMRT alone with 1 cm posterior PTV margin was effective and safe for patients with localized prostate cancer.

Outcome and patient-reported toxicity in localised prostate cancer treated with dose-escalated hypofractionated intensity-modulated radiotherapy

Objective

To report outcomes and late toxicity for a hypofractionated dose-escalated radiotherapy schedule in patients treated using intensity-modulated radiotherapy (IMRT) for localised prostate cancer.

Materials and methods

Eighty-eight men with localised prostate cancer were treated with 57 Gy in 19 daily fractions over 4 weeks. A total of 70 out of 88 had high-risk disease. Overall survival, cause-specific survival and biochemical progression-free survival (bPFS, Phoenix definition) were reported. Toxicity was measured retrospectively using Radiation Therapy Oncology Group (RTOG) criteria and assessed prospectively with a validated Late Effects in Normal Tissues Subjective, Objective, Management and Analytic (LENT/SOMA) patient questionnaire.

Results

At 5 years, overall survival was 84%, cause-specific survival 88% and bPFS 65%. In patients with high-risk disease, 5-year bPFS was 62%. There was no RTOG toxicity above grade III. LENT/SOMA questionnaires were returned by 74% patients. Median scores for bowel and urinary function were <1. Maximum bowel and urinary toxicity scores ≥2 were reported by 64% and 59% of patients, respectively. The median score for sexual function was 1·5, but nearly all (96%) patients recorded a toxicity score ≥2 for at least one question.

Conclusions

Dose-escalated hypofractionated radiotherapy delivered using IMRT has promising outcomes and acceptable late toxicity. This fractionation schedule is being compared with conventional treatment within an on-going multicentre phase III clinical trial.

Preliminary toxicity analysis of 3-dimensional conformal radiation therapy versus intensity modulated radiation therapy on the high-dose arm of the Radiation Therapy Oncology Group 0126 prostate cancer trial

PURPOSE

To give a preliminary report of clinical and treatment factors associated with toxicity in men receiving high-dose radiation therapy (RT) on a phase 3 dose-escalation trial.

METHODS AND MATERIALS

The trial was initiated with 3-dimensional conformal RT (3D-CRT) and amended after 1 year to allow intensity modulated RT (IMRT). Patients treated with 3D-CRT received 55.8 Gy to a planning target volume that included the prostate and seminal vesicles, then 23.4 Gy to prostate only. The IMRT patients were treated to the prostate and proximal seminal vesicles to 79.2 Gy. Common Toxicity Criteria, version 2.0, and Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer late morbidity scores were used for acute and late effects.

RESULTS

Of 763 patients randomized to the 79.2-Gy arm of Radiation Therapy Oncology Group 0126 protocol, 748 were eligible and evaluable: 491 and 257 were treated with 3D-CRT and IMRT, respectively. For both bladder and rectum, the volumes receiving 65, 70, and 75 Gy were significantly lower with IMRT (all P<.0001). For grade (G) 2+ acute gastrointestinal/genitourinary (GI/GU) toxicity, both univariate and multivariate analyses showed a statistically significant decrease in G2+ acute collective GI/GU toxicity for IMRT. There were no significant differences with 3D-CRT or IMRT for acute or late G2+ or 3+ GU toxicities. Univariate analysis showed a statistically significant decrease in late G2+ GI toxicity for IMRT (P=.039). On multivariate analysis, IMRT showed a 26% reduction in G2+ late GI toxicity (P=.099). Acute G2+ toxicity was associated with late G3+ toxicity (P=.005). With dose-volume histogram data in the multivariate analysis, RT modality was not significant, whereas white race (P=.001) and rectal V70 ≥15% were associated with G2+ rectal toxicity (P=.034).

CONCLUSIONS

Intensity modulated RT is associated with a significant reduction in acute G2+ GI/GU toxicity. There is a trend for a clinically meaningful reduction in late G2+ GI toxicity with IMRT. The occurrence of acute GI toxicity and large (>15%) volumes of rectum >70 Gy are associated with late rectal toxicity.

Dosimetric effects of bladder and rectal contrast agents in prostate radiotherapy

Background and purpose

Accurate delineation of the target volume and organs at risk (OARs) are vital to ensure systematic errors are small. The use of contrast agents (CAs) in the bladder and rectum may aid contouring and reduce inter and intra-observer variability. The aim of this study was to evaluate the dosimetric effect of the presence of such contrast on the monitor units (MUs), planning target volume (PTV), rectum and bladder.

Materials and methods

The prostate, seminal vesicles, rectum and bladder were contoured by a single observer on ten patients with bladder and rectal contrast. To evaluate the dosimetric effect of the presence of contrast, the density of the ten patients with contrast in the bladder and rectum was virtually changed to 1 g/cm3. A four-field 15 MV conformal radiation therapy technique was applied in which dose volume histograms and MUs were compared using computed tomographic (CT) density and the 1 g/cm3density.

Results

The presence of contrast resulted in a 0·09% (<1 MU) increase in anterior MUs and decrease of 1% (<1 MU) in the posterior beam MUs. Lateral beams were not affected. The PTV and bladder dose increased slightly without contrast. The rectum showed a maximum change of 0·62% dose among the measured dose values. A maximum dose of 0·3 Gy at the 30% volume was also seen.

Conclusions

The dosimetric effect of bladder and rectal CAs on MUs, dose to the PTV and OARs in using this technique was very small. This would not be clinically significant, but only if the extreme limits of dose volume constraints were being reached.

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.

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.

Outcomes and tolerance of human immunodeficiency virus--positive U.S. veterans undergoing dose-escalated external beam radiotherapy for localized prostate cancer

INTRODUCTION

There are little data on the outcomes and tolerance, as well as the impact on the CD4 counts, of human immunodeficiency virus (HIV)-positive patients with prostate cancer who undergo high-dose external beam radiotherapy.

MATERIALS AND METHODS

We identified 15 HIV-positive patients with prostate cancer who were treated with external beam radiation to a dose ≥ 75.6 Gy at the New York Harbor Department of Veterans Affairs between 2003 and 2010. Kaplan-Meier analyses were used to measure biochemical control outcomes. Toxicity and CD4 counts before, after, and during treatments were analyzed.

RESULTS

A total of 15 patients were identified, with a median follow-up period of 49 months. There were 2 biochemical failures, which occurred at 28 months and 63 months, respectively. In neither of these 2 patients was there evidence of metastatic disease. The overall 5-year biochemical control was 92.3%. There appeared to be a consistent decline in the CD4 counts both during and immediately after the radiation treatments. Most of these patients had a subsequent improvement in their CD4 counts. Toxicity was mild overall, though there was 1 patient who developed rectal bleeding 11 months post treatment, which required argon plasma coagulation.

CONCLUSION

Dose-escalated external beam radiation is well tolerated in HIV-positive patients with durable biochemical control and mild toxicity. A substantial decline in CD4 counts is associated with the radiation; therefore, these counts need to be monitored closely, in conjunction with the infectious-disease specialist.

Future directions from past experience: a century of prostate radiotherapy

Prostate cancer is the most commonly diagnosed noncutaneous malignancy in men, yet 100 years ago it was considered a rare disease. Over the past century, radiation therapy has evolved from a radium source placed in the urethra to today's advanced proton therapy delivered by only a few specialized centers. As techniques in radiation have evolved, the treatment of localized prostate cancer has become one of the most debated topics in oncology. Today, patients with prostate cancer must often make a difficult decision between multiple treatment modalities, each with the risk of permanent sequelae, without robust randomized data to compare every treatment option. Meanwhile, opinions of urologists and radiation oncologists about the risks and benefits involved with each modality vary widely. Further complicating the issue is rapidly advancing technology which often outpaces clinical data. This article represents a complete description of the evolution of prostate cancer radiation therapy with the goal of illuminating the historical basis for current challenges facing oncologists and their patients.

Evidence based radiation oncology with existing technology

AIM

To assess the real contribution of modern radiation therapy (RT) technology in the more common tumoral types in Central America, Caribbean and South America.

BACKGROUND

RT is an essential tool in the management of cancer. RT can be either palliative or of curative intent. In general, for palliative radiotherapy, major technologies are not needed.

MATERIALS AND METHODS

We analyzed the contribution of RT technology based on published evidence for breast, lung, gastric, gallbladder, colorectal, prostate and cervix cancer in terms of disease control, survival or toxicity with especial focus on Latin America.

RESULTS

Findings indicate that three dimensional conformal radiation therapy (3D RT) is the gold standard in most common type of cancer in the studied regions. Prostate cancer is probably the pathology that has more benefits when using new RT technology such as intensity modulated radiation therapy (IMRT) versus 3DRT in terms of toxicity and biochemical progression-free survival.

CONCLUSIONS

In light of the changes in technology, the ever-increasing access of developing countries to such technology, and its current coverage in Latin America, any efforts in this area should be aimed at improving the quality of the radiotherapy departments and centers that are already in place.

Randomized trial of hypofractionated external-beam radiotherapy for prostate cancer

PURPOSE

To determine if escalated radiation dose using hypofractionation significantly reduces biochemical and/or clinical disease failure (BCDF) in men treated primarily for prostate cancer.

PATIENTS AND METHODS

Between June 2002 and May 2006, men with favorable- to high-risk prostate cancer were randomly allocated to receive 76 Gy in 38 fractions at 2.0 Gy per fraction (conventional fractionation intensity-modulated radiation therapy [CIMRT]) versus 70.2 Gy in 26 fractions at 2.7 Gy per fraction (hypofractionated IMRT [HIMRT]); the latter was estimated to be equivalent to 84.4 Gy in 2.0 Gy fractions. High-risk patients received long-term androgen deprivation therapy (ADT), and some intermediate-risk patients received short-term ADT. The primary end point was the cumulative incidence of BCDF. Secondarily, toxicity was assessed.

RESULTS

There were 303 assessable patients with a median follow-up of 68.4 months. No significant differences were seen between the treatment arms in terms of the distribution of patients by clinicopathologic or treatment-related (ADT use and length) factors. The 5-year rates of BCDF were 21.4% (95% CI, 14.8% to 28.7%) for CIMRT and 23.3% (95% CI, 16.4% to 31.0%) for HIMRT (P = .745). There were no statistically significant differences in late toxicity between the arms; however, in subgroup analysis, patients with compromised urinary function before enrollment had significantly worse urinary function after HIMRT.

CONCLUSION

The hypofractionation regimen did not result in a significant reduction in BCDF; however, it is delivered in 2.5 fewer weeks. Men with compromised urinary function before treatment may not be ideal candidates for this approach.

Prostate stereotactic body radiotherapy with simultaneous integrated boost: which is the best planning method?

Background

The delivery of a simultaneous integrated boost to the intra-prostatic tumour nodule may improve local control. The ability to deliver such treatments with hypofractionated SBRT was attempted using RapidArc (Varian Medical systems, Palo Alto, CA) and Multiplan (Accuray inc, Sunnyvale, CA).

Materials and methods

15 patients with dominant prostate nodules had RapidArc and Multiplan plans created using a 5 mm isotropic margin, except 3 mm posteriorly, aiming to deliver 47.5 Gy in 5 fractions to the boost whilst treating the whole prostate to 36.25 Gy in 5 fractions. An additional RapidArc plan was created using an 8 mm isotropic margin, except 5 mm posteriorly, to account for lack of intrafraction tracking.

Results

Both RapidArc and Multiplan can produce clinically acceptable boost plans to a dose of 47.5 Gy in 5 fractions. The mean rectal doses were lower for RapidArc plans (D50 13.2 Gy vs 15.5 Gy) but the number of missed constraints was the same for both planning methods (11/75). When the margin was increased to 8 mm/5 mm for the RapidArc plans to account for intrafraction motion, 37/75 constraints were missed.

Conclusions

RapidArc and Multiplan can produce clinically acceptable simultaneous integrated boost plans, but the mean rectal D50 and D20 with RapidArc are lower. If the margins are increased to account for intrafraction motion, the RapidArc plans exceed at least one dose constraint in 13/15 cases. Delivering a simultaneous boost with hypofractionation appears feasible, but requires small margins needing intrafraction motion tracking.

Dosimetric comparison between IMRT delivery modes: Step-and-shoot, sliding window, and volumetric modulated arc therapy - for whole pelvis radiation therapy of intermediate-to-high risk prostate adenocarcinoma

THIS STUDY WAS PERFORMED TO EVALUATE DOSIMETRIC DIFFERENCES BETWEEN CURRENT INTENSITY MODULATED RADIATION THERAPY (IMRT) DELIVERY MODES: Step-and-shoot (SS), sliding window (SW), and volumetric modulated arc therapy (VMAT). Plans for 15 prostate cancer patients with 10 MV photon beams using each IMRT mode were generated. Patients had three planning target volumes (PTVs) including prostate, prostate plus seminal vesicles, and pelvic lymphatics. Dose volume histograms (DVHs) of PTVs and organs at risk (OARs), tumor control probability (TCP) and normal tissue complication probabilities (NTCPs), conformation number, and monitor units (MUs) used were compared. Statistical analysis was performed using the analysis of variance (ANOVA) technique. The TCPs were < 99% with insignificant differences among modalities (P > 0.99). Doses to all critical structures were higher on average with SW method compared to SS, but insignificant. NTCP values were lowest for VMAT in all structures excepting bladder. Normal tissue volumes receiving doses in the 20-30 Gy range were reduced for VMAT compared to SS. Percentage of MUs required for VMAT to deliver a comparable plan to SS and SW was at least 40% less. In conclusion, similar target coverage and normal tissue doses were found by the three compared modes and the dosimetric differences were small.

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.

Stereotactic body radiotherapy in prostate cancer: is rapidarc a better solution than cyberknife?

AIMS

There is increasing interest in stereotactic body radiotherapy (SBRT) for the management of prostate adenocarcinoma, with encouraging initial biological progression-free survival results. However, the limited literature is dominated by the use of the Cyberknife platform. This led to an international phase III study comparing outcomes for Cyberknife SBRT with both surgery and conventionally fractionated intensity-modulated radiotherapy (the PACE study). We aim to compare Cyberknife delivery with Rapidarc, a more widely available treatment platform.

MATERIALS AND METHODS

The scans of six previous prostate radiotherapy patients with a range of prostate sizes were chosen. The clinical target volume was defined as the prostate gland, with 3 mm added for the Cyberknife planning target volume (PTV) and 5 mm for the Rapidarc PTV. Accuray multiplan v. 4.5 was used for planning with delivery on a Cyberknife VSI system v9.5; Varian Eclipse v10 was used for Rapidarc planning with delivery using a Varian 21EX linear accelerator. Both systems attempted to deliver at least 35 Gy to the PTV in five fractions with PTV heterogeneity <12%.

RESULTS

All organ at risk (OAR) constraints were achieved by both platforms, whereas the Cyberknife failed to achieve the desired PTV homogeneity constraint in two cases. In other OARs without constraints, Cyberknife delivered higher doses. The volume of the 35 Gy isodose was slightly larger with Rapidarc, but conversely at doses <35 Gy normal tissues received higher doses with Cyberknife. The mean planning and delivery time was in favour of Rapidarc.

CONCLUSIONS

We have shown that there is no discernible dosimetric advantage to choosing Cyberknife over Rapidarc for SBRT delivery in prostate cancer. Given the significant benefits of Rapidarc in terms of availability, planning and delivery time, the authors suggest that phase III trials of SBRT should include Rapidarc or equivalent rotational delivery platforms.

Focal low-dose rate brachytherapy for the treatment of prostate cancer

Whole-gland low-dose rate (LDR) brachytherapy has been a well-established modality of treating low-risk prostate cancer. Treatment in a focal manner has the advantages of reduced toxicity to surrounding organs. Focal treatment using LDR brachytherapy has been relatively unexplored, but it may offer advantages over other modalities that have established experiences with a focal approach. This is particularly true as prostate cancer is being detected at an earlier and more localized stage with the advent of better detection methods and newer imaging modalities.

Long-term outcomes for men with high-risk prostate cancer treated definitively with external beam radiotherapy with or without androgen deprivation

BACKGROUND

Men with high-risk prostate cancer are often thought to have very poor outcomes in terms of disease control and survival even after definitive treatment. However, results after external beam radiotherapy have improved significantly through dose escalation and the use of androgen deprivation therapy (ADT). This report describes long-term findings after low-dose (< 75.6 Gy) or high-dose (≥ 75.6 Gy) external beam radiation, with or without ADT.

METHODS

This analysis included 741 men with high-risk prostate cancer (clinical classification ≥ T3, Gleason score ≥ 8, or prostate-specific antigen level ≥ 20 ng/mL) treated with external beam radiotherapy at a single tertiary institution from 1987 through 2004. The radiation dose ranged from 60 to 79.3 Gy (median, 70 Gy); 295 men had received ADT for ≥ 2 years, and the median follow-up time was 8.3 years.

RESULTS

The 5- and 10-year actuarial overall survival rates were significantly better for men treated with the higher radiation dose (no ADT plus ≥ 75.6 Gy, 87.3% and 72.0%, respectively; and ADT plus ≥ 75.6 Gy, 92.3% and 72%, respectively) (P = .0035). The corresponding 5- and 10-year biochemical failure-free survival rates were significantly better for patients treated with both ADT and higher radiation dose (82% and 77%, P < .0001). At 5 years, men who had not received ADT and had received radiation dose < 75.6 Gy had higher clinical local failure rates than those given ADT and radiation dose ≥ 75.6 Gy (24.2% versus 0%, P < .0001). The 10-year symptomatic local failure rate was only 2% for all patients.

CONCLUSIONS

Contrary to lingering historical perceptions, treatment of high-risk prostate cancer with modern, high-dose, external beam radiotherapy and ADT can produce better biochemical, clinical, and survival outcomes over those from previous eras. Specifically, symptomatic local failure is uncommon, and few men die of prostate cancer even 10 or more years after treatment.

A retrospective planning analysis comparing intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) using two optimization algorithms for the treatment of early-stage prostate cancer

INTRODUCTION

The primary aim of this study is to compare intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) for the radical treatment of prostate cancer using version 10.0 (v10.0) of Varian Medical Systems, RapidArc radiation oncology system. Particular focus was placed on plan quality and the implications on departmental resources. The secondary objective was to compare the results in v10.0 to the preceding version 8.6 (v8.6).

METHODS

Twenty prostate cancer cases were retrospectively planned using v10.0 of Varian's Eclipse and RapidArc software. Three planning techniques were performed: a 5-field IMRT, VMAT using one arc (VMAT-1A), and VMAT with two arcs (VMAT-2A). Plan quality was assessed by examining homogeneity, conformity, the number of monitor units (MUs) utilized, and dose to the organs at risk (OAR). Resource implications were assessed by examining planning and treatment times. The results obtained using v10.0 were also compared to those previously reported by our group for v8.6.

RESULTS

In v10.0, each technique was able to produce a dose distribution that achieved the departmental planning guidelines. The IMRT plans were produced faster than VMAT plans and displayed improved homogeneity. The VMAT plans provided better conformity to the target volume, improved dose to the OAR, and required fewer MUs. Treatments using VMAT-1A were significantly faster than both IMRT and VMAT-2A. Comparison between versions 8.6 and 10.0 revealed that in the newer version, VMAT planning was significantly faster and the quality of the VMAT dose distributions produced were of a better quality.

CONCLUSION

VMAT (v10.0) using one or two arcs provides an acceptable alternative to IMRT for the treatment of prostate cancer. VMAT-1A has the greatest impact on reducing treatment time.

Nomograms to predict late urinary toxicity after prostate cancer radiotherapy

OBJECTIVE

To analyze late urinary toxicity after prostate cancer radiotherapy (RT): symptom description and identification of patient characteristics or treatment parameters allowing for the generation of nomograms.

METHODS

Nine hundred and sixty-five patients underwent RT in seventeen French centers for localized prostate cancer. Median total dose was 70 Gy (range, 65-80 Gy), using different fractionations (2 or 2.5 Gy/day) and techniques. Late urinary toxicity and the corresponding symptoms (urinary frequency, incontinence, dysuria/decreased stream, and hematuria) were prospectively assessed in half of the patients using the LENT-SOMA classification. Univariate and multivariate Cox regression models addressed patient or treatment-related predictors of late urinary toxicity (≥grade 2). Nomograms were built up, and their performance was assessed.

RESULTS

The median follow-up was 61 months. The 5-year (≥grade 2) global urinary toxicity, urinary frequency, hematuria, dysuria, and urinary incontinence rates were 15, 10, 5, 3 and 1 %, respectively. The 5-year (≥grade 3) urinary toxicity rate was 3 %. The following parameters significantly increased the 5-year risk of global urinary toxicity (≥grade 2): anticoagulant treatment (RR = 2.35), total dose (RR = 1.09), and age (RR = 1.06). Urinary frequency was increased by the total dose (RR = 1.07) and diabetes (RR = 4). Hematuria was increased by anticoagulant treatment (RR = 2.9). Dysuria was increased by the total dose (RR = 1.1). Corresponding nomograms and their calibration plots were generated. Nomogram performance should be validated with external data.

CONCLUSIONS

The first nomograms to predict late urinary toxicity but also specific urinary symptoms after prostate RT were generated, contributing to prostate cancer treatment decision.

Divorcing diagnosis from treatment: contemporary management of low-risk prostate cancer

Today, the majority of men with newly diagnosed prostate cancer will present with low-risk features of the disease. Because prostate cancer often takes an insidious course, it is debated whether the majority of these men require radical treatment and the accompanying derangement of quality of life domains imposed by surgery, radiation, and hormonal therapy. Investigators have identified various selection criteria for "insignificant disease," or that which can be monitored for disease progression while safely delaying radical treatment. In addition to the ideal definition of low risk, a lack of randomized trials comparing the various options for treatment in this group of men poses a great challenge for urologists. Early outcomes from active surveillance cohorts support its use in carefully selected men with low-risk disease features, but frequent monitoring is required. Patient selection and disease monitoring methods will require refinement that will likely be accomplished through the increased use of biomarkers and specialized imaging techniques.

Radical radiotherapy in high-risk prostate cancer patients with high or ultra-high initial PSA levels: a single institution analysis

PURPOSE

Purpose of this study is to analyze outcomes and pre-treatment prognostic factors in high-risk prostate cancer patients with initial PSA ≥ 20 ng/mL, treated with high-dose external beam radiotherapy (EBRT) and androgen deprivation therapy (ADT) in a single institution.

METHODS

Between March 2003 and December 2011, 155 consecutive high-risk prostate cancer patients (a) presenting with pre-treatment PSA level ≥ 20 ng/mL, (b) treated with definitive EBRT, and (c) with a minimum follow-up of 24 months were included in this retrospective analysis. Phoenix definition was used to define biochemical control. Primary endpoints were as follows: biochemical disease-free survival (bDFS), distant metastasis-free survival (DMFS), cancer-specific survival (CSS) and overall survival (OS). Multivariate analysis was performed to determine the independent prognostic impact of pre-treatment clinical factors [T stage, PSA, and Gleason score (GS)].

RESULTS

At a median follow-up time of 62 months, actuarial bDFS, DMFS, CSS, and OS at 5 years were 64.8, 85.2, 95.8, and 94.4 %, respectively. On multivariate analysis, only GS was significantly associated with three clinical endpoints (bDFS: HR 1.6; p = 0.022, CSS: HR 4.27, p = 0.044, OS: HR 2.6; p = 0.038). Pre-treatment zenith PSA was associated only with bDFS (HR 1.87; p = 0.027).

CONCLUSIONS

Patients with "high" PSA levels (≥ 20 ng/mL) showed favorable clinical outcomes, supporting the role of local radiotherapy as primary therapy in combination with long-term ADT in patients with high PSA levels at diagnosis. A GS of 8-10 is the strongest predictor of outcome.

Individualized image-based lymph node irradiation for prostate cancer

Controversy surrounds the benefit of whole pelvis radiotherapy (WPRT) over prostate-only radiotherapy (PORT) for intermediate-risk and high-risk patients with prostate cancer. In the PSA screening era, two large randomized trials as well as multiple retrospective studies comparing WPRT with PORT have been performed, albeit with contradictory results. Data regarding the use of WPRT in patients with biochemical recurrence after prostatectomy are scarce. As a consequence, the practice of WPRT varies worldwide. Advanced highly accurate imaging methods for the detection of lymph node metastases in patients with prostate cancer have been developed, such as PET, single photon emission computed tomography (SPECT), diffusion-weighted MRI and magnetic resonance lymphography (MRL). The use of these new imaging methods might improve nodal irradiation, as they can be used not only for selection of patients, but also for accurately determining the target volume to reduce geographical miss. Furthermore, these new techniques can enable dose escalation to involved lymph nodes.

A prospective study on pain score with transperineal prostatic gold seed fiducial implantation under local anesthetic alone

BACKGROUND

The purpose of this study was to monitor patient pain score with transperineal prostatic gold seed implantation in the absence of conscious sedation.

METHODS

All patients who were scheduled for image-guided external beam radiation (IGRT) and referred for gold seed fiducials were eligible to participate. Gold seed implants were performed by two radiation oncologists between December 2007 and April 2008. Patients received only local and deep anesthetic. No patients had prophylactic IV cannulation for the procedure. Three gold seeds were inserted transperineally into the prostate. A visual analogue scale from 0 to 10 was used to assess the pain at baseline, local and deep anesthetic infiltration, with each seed drop, and after the completion of the procedure.

RESULTS

A total of 30 patients were accrued to this study. The highest recorded increase in pain score was at the time point of deep local anesthesia, at which the mean pain score was 3.8. The mean pain scores at each seed drop were 0.8 (standard deviation [SD]=1.24), 1 (SD=1.26), and 0.5 (SD=0.90), respectively. All gold seed insertion procedures were well-tolerated, with no patients having significant pain post-procedure, and no significant procedural complications. There were only slight increases in dysuria, urinary frequency, constipation, urinary retention and flatulence in 7 patients - none of which required intervention.

INTERPRETATION

Transperineal ultrasound-guided gold seed implantation without conscious sedation is well-tolerated and associated with a low complication rate. It is a convenient outpatient procedure obviating the need for resource intensive postoperative monitoring.

High dose rate brachytherapy as monotherapy for localised prostate cancer: a hypofractionated two-implant approach in 351 consecutive patients

BACKGROUND

To report the clinical outcome of high dose rate brachytherapy as sole treatment for clinically localised prostate cancer.

METHODS

Between March 2004 and January 2008, a total of 351 consecutive patients with clinically localised prostate cancer were treated with transrectal ultrasound guided high dose rate brachytherapy. The prescribed dose was 38.0 Gy in four fractions (two implants of two fractions each of 9.5 Gy with an interval of 14 days between the implants) delivered to an intraoperative transrectal ultrasound real-time defined planning treatment volume. Biochemical failure was defined according to the Phoenix Consensus and toxicity evaluated using the Common Toxicity Criteria for Adverse Events version 3.

RESULTS

The median follow-up time was 59.3 months. The 36 and 60 month biochemical control and metastasis-free survival rates were respectively 98%, 94% and 99%, 98%. Toxicity was scored per event with 4.8% acute Grade 3 genitourinary and no acute Grade 3 gastrointestinal toxicity. Late Grade 3 genitourinary and gastrointestinal toxicity were respectively 3.4% and 1.4%. No instances of Grade 4 or greater acute or late adverse events were reported.

CONCLUSIONS

Our results confirm high dose rate brachytherapy as safe and effective monotherapy for clinically organ-confined prostate cancer.

Statistical analysis of dose-volume profiles and its implication for radiation therapy planning in prostate carcinoma

PURPOSE

The study aimed to analyze the dose-volume profiles of 3-dimensional radiation therapy (3D-CRT) and intensity modulated RT (IMRT) in the treatment of prostate carcinoma and to specify the profiles responsible for the development of gastrointestinal (GI) toxicity.

METHODS AND MATERIALS

In the period 1997 to 2007, 483 patients with prostate carcinoma in stage T1-3 N0 (pN0) M0 were treated with definitive RT. Two groups of patients were defined for the analysis: the 3D-CRT group (n=305 patients) and the IMRT group (n=178 patients). In the entire cohort of 483 patients, the median follow-up time reached 4.4 years (range, 2.0-11.7 years). The cumulative absolute and relative volumes of irradiated rectum exposed to a given dose (area under the dose-volume curve, AUC) were estimated. The receiver operating characteristic analysis was then used to search for the optimal dose and volume cutoff points with the potential to distinguish patients with enhanced or escalated toxicity.

RESULTS

Despite the application of high doses (78-82 Gy) in the IMRT group, GI toxicity was lower in that group than in the group treated by 3D-CRT with prescribed doses of 70 to 74 Gy. Both RT methods showed specific rectal dose-volume distribution curves. The total AUC values for IMRT were significantly lower than those for 3D-CRT. Furthermore, IMRT significantly decreased the rectal volume receiving low to intermediate radiation doses in comparison with 3D-CRT; specific cutoff limits predictable for the level of GI toxicity are presented and defined in our work.

CONCLUSIONS

Total area under the dose-volume profiles and specific cutoff points in low and intermediate dose levels have significant predictive potential toward the RT GI toxicity. In treatment planning, it seems that it is valuable to take into consideration the entire dose-volume primary distribution.

Multi-institutional prospective evaluation of bowel quality of life after prostate external beam radiation therapy identifies patient and treatment factors associated with patient-reported outcomes: the PROSTQA experience

PURPOSE

To evaluate patients treated with external beam radiation therapy as part of the multicenter Prostate Cancer Outcomes and Satisfaction with Treatment Quality Assessment (PROSTQA), to identify factors associated with posttreatment patient-reported bowel health-related quality of life (HRQOL).

METHODS AND MATERIALS

Pretreatment characteristics and treatment details among 292 men were evaluated using a general linear mixed model for their association with measured HRQOL by the Expanded Prostate Cancer Index Composite instrument through 2 years after enrollment.

RESULTS

Bowel HRQOL had a median score of 100 (interquartile range 91.7-100) pretreatment and 95.8 (interquartile range 83.3-100) at 2 years, representing new moderate/big problems in 11% for urgency, 7% for frequency, 4% for bloody stools, and 8% for an overall bowel problems. Baseline bowel score was the strongest predictor for all 2-year endpoints. In multivariable models, a volume of rectum ≥25% treated to 70 Gy (V70) yielded a clinically significant 9.3-point lower bowel score (95% confidence interval [CI] 16.8-1.7, P=.015) and predicted increased risks for moderate to big fecal incontinence (P=.0008). No other radiation therapy treatment-related variables influenced moderate to big changes in rectal HRQOL. However, on multivariate analyses V70 ≥25% was associated with increases in small, moderate, or big problems with the following: incontinence (3.9-fold; 95% CI 1.1-13.4, P=.03), rectal bleeding (3.6-fold; 95% CI 1.3-10.2, P=.018), and bowel urgency (2.9-fold; 95% CI 1.1-7.6, P=.026). Aspirin use correlated with a clinically significant 4.7-point lower bowel summary score (95% CI 9.0-0.4, P=.03) and an increase in small, moderate, or big problems with bloody stools (2.8-fold; 95% CI 1.2-6.4, P=.018). Intensity modulated radiation therapy was associated with higher radiation therapy doses to the prostate and lower doses to the rectum but did not independently correlate with bowel HRQOL.

CONCLUSION

After contemporary dose-escalated external beam radiation therapy up to 11% of patients have newly identified moderate/big problems with bowel HRQOL 2 years after treatment. Bowel HRQOL is related to baseline function, rectal V70, and aspirin use. Finally, our findings validate the commonly utilized cut-point of rectal V70 ≥25% as having significant impact on patient-reported outcomes.

A phase II study of hypofractionated proton therapy for prostate cancer

BACKGROUND

Hypofractionated radiotherapy potentially offers therapeutic gain for prostate cancer. We investigated the feasibility of hypofractionated proton therapy (PT).

MATERIAL AND METHODS

Eighty-two patients with biopsy-proven T1-3N0M0 prostate adenocarcinoma and no history of androgen deprivation therapy were randomly assigned to five different dose schedules: Arm 1, 60 CGE (cobalt gray equivalent = proton dose in Gy × 1.1)/20 fractions/5 weeks; Arm 2, 54 CGE/15 fractions/5 weeks; Arm 3, 47 CGE/10 fractions/5 weeks; Arm 4, 35 CGE/5 fractions/2.5 weeks; or Arm 5, 35 CGE/5 fractions/5 weeks.

RESULTS

The median follow-up duration was 42 months (11-52 months). The acute GI and GU grade ≥ 2 toxicity rates were 0 and 5%, respectively. The late GI and GU grade ≥ 2 toxicity rates were 16% and 7%, respectively. The best arm for acute GU toxicity was Arm 3, while that for late GI toxicity was Arm 2 in which none had grade ≥ 2 toxicity. The four-year American Society for Therapeutic Radiology and Oncology and Nadir + 2ng/ml BCF free survival (BCFFS) rates were 85% and 86%, respectively.

CONCLUSIONS

Hypofractionated PT for patients with prostate adenocarcinoma as used in this study is feasible with an acceptable toxicity profile. As the BCFFS rates do not seem to be inferior to those produced using conventional fractionation, the application of hypofractionated PT may save patients time and money.

Brachytherapy in Men with Prostate Cancer: Update on Indications and Outcomes

Brachytherapy (BT), using either a low-dose-rate (LDR) or mostly high-dose-rate (HDR) technique, is the device able to deliver the highest dose-rate in the most conformal way It is used as monotherapy or in combination with external beam radiotherapy (EBRT). LDR-BT is mostly used as monotherapy; HDR-BT is combined with EBRT +/– adjuvant hormone therapy In patients with low-risk disease and in selected intermediate-risk patients, LDR-BT ensures long-term good disease control rates and HDR-BT shows similar results, even if with shorter follow-up. In patients with intermediate/high risk disease the combination therapy (EBRT + HDR-BT) provides better oncological outcomes compared to EBRT monotherapy, even if the role of adjuvant hormone therapy is still unclear. Literature shows variable efficacy of BT in case of local recurrence after EBRT and radical prostatectomy even if few cases have been reported with short follow-up. Side effects are acceptable (urogenital toxicity, urinary incontinence, sexual function) and comparable with the other treatment modalities. So far, randomized controlled trials comparing the different treatment modalities are necessary to clarify indications and real efficacy.

Maximizing dosimetric benefits of IMRT in the treatment of localized prostate cancer through multicriteria optimization planning

We examine the quality of plans created using multicriteria optimization (MCO) treatment planning in intensity-modulated radiation therapy (IMRT) in treatment of localized prostate cancer. Nine random cases of patients receiving IMRT to the prostate were selected. Each case was associated with a clinically approved plan created using Corvus. The cases were replanned using MCO-based planning in RayStation. Dose-volume histogram data from both planning systems were presented to 2 radiation oncologists in a blinded evaluation, and were compared at a number of dose-volume points. Both physicians rated all 9 MCO plans as superior to the clinically approved plans (p<10(-5)). Target coverage was equivalent (p = 0.81). Maximum doses to the prostate and bladder and the V50 and V70 to the anterior rectum were reduced in all MCO plans (p<0.05). Treatment planning time with MCO took approximately 60 minutes per case. MCO-based planning for prostate IMRT is efficient and produces high-quality plans with good target homogeneity and sparing of the anterior rectum, bladder, and femoral heads, without sacrificing target coverage.