Three dimensional conformal radiotherapy for the treatment of prostate cancer: low risk of chronic rectal morbidity observed in a large series of patients

Real-time, volumetric imaging of radiation dose delivery deep into the liver during cancer treatment

Ionizing radiation acoustic imaging (iRAI) allows online monitoring of radiation's interactions with tissues during radiation therapy, providing real-time, adaptive feedback for cancer treatments. We describe an iRAI volumetric imaging system that enables mapping of the three-dimensional (3D) radiation dose distribution in a complex clinical radiotherapy treatment. The method relies on a two-dimensional matrix array transducer and a matching multi-channel preamplifier board. The feasibility of imaging temporal 3D dose accumulation was first validated in a tissue-mimicking phantom. Next, semiquantitative iRAI relative dose measurements were verified in vivo in a rabbit model. Finally, real-time visualization of the 3D radiation dose delivered to a patient with liver metastases was accomplished with a clinical linear accelerator. These studies demonstrate the potential of iRAI to monitor and quantify the 3D radiation dose deposition during treatment, potentially improving radiotherapy treatment efficacy using real-time adaptive treatment.

Dual-Modality X-Ray-Induced Radiation Acoustic and Ultrasound Imaging for Real-Time Monitoring of Radiotherapy

Objective. The goal is to increase the precision of radiation delivery during radiotherapy by tracking the movements of the tumor and other surrounding normal tissues due to respiratory and other body motions. Introduction. This work presents the recent advancement of X-ray-induced radiation acoustic imaging (xRAI) technology and the evaluation of its feasibility for real-time monitoring of geometric and morphological misalignments of the X-ray field with respect to the target tissue by combining xRAI with established ultrasound (US) imaging, thereby improving radiotherapy tumor eradication and limiting treatment side effects. Methods. An integrated xRAI and B-mode US dual-modality system was established based on a clinic-ready research US platform. The performance of this dual-modality imaging system was evaluated via experiments on phantoms and ex vivo and in vivo rabbit liver models. Results. This system can alternatively switch between the xRAI and the US modes, with spatial resolutions of 1.1 mm and 0.37 mm, respectively. 300 times signal averaging was required for xRAI to reach a satisfactory signal-to-noise ratio, and a frame rate of 1.1 Hz was achieved with a clinical linear accelerator. The US imaging frame rate was 22 Hz, which is sufficient for real-time monitoring of the displacement of the target due to internal body motion. Conclusion. Our developed xRAI, in combination with US imaging, allows for mapping of the dose deposition in biological samples in vivo, in real-time, during radiotherapy. Impact Statement. The US-based image-guided radiotherapy system presented in this work holds great potential for personalized cancer treatment and better outcomes.

Innovations in Three-Dimensional Treatment Planning and Quality Assurance

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

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

BACKGROUND

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

METHODS

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

FINDINGS

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

INTERPRETATION

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

FUNDING

UK Medical Research Council.

ACR Appropriateness Criteria® definitive external beam irradiation in stage T1 and T2 prostate cancer

PURPOSE

: External beam radiation therapy is a standard of care treatment for men who present with clinically localized (T1-T2) prostate cancer. The purpose of this review was to provide clarification on the appropriateness criteria and management considerations for the treatment of prostate cancer with external beam radiation therapy.

METHODS

: A panel consisting of physicians with expertise on prostate cancer was assembled and provided with a number of clinical scenarios for consensus treatment and management guidelines. Prostate cancer patient vignettes were presented along with specific management recommendations based on an extensive review of the modern external beam radiotherapy literature. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer reviewed journals and the application of a well established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances, where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

RESULTS

: Modern external beam radiation therapy series demonstrate favorable biochemical control rates for patients with localized prostate cancer. Morbidity profiles are also favorable and it is clear that this is enhanced by modern techniques like 3-dimensional conformal radiation therapy and intensity-modulated radiation therapy. An active area of investigation is evaluating the use of hypofractionated dosing.

CONCLUSIONS

: Continued investigation to refine patient selection, external beam radiation technology application, and alternative dosing schedules should result in further improvements in biochemical outcome and decreased morbidity with external beam radiation treatment for localized prostate cancer.

Low-dose rate brachytherapy for men with localized prostate cancer

BACKGROUND

Localized prostate cancer is a slow growing tumor for many years for the majority of affected men. Low-dose rate brachytherapy (LDR-BT) is short-distance radiotherapy using low-energy radioactive sources. LDR-BT has been recommended for men with low risk localized prostate cancer.

OBJECTIVES

To assess the benefit and harm of LDR-BT compared to radical prostatectomy (RP), external beam radiotherapy (EBRT), and no primary therapy (NPT) in men with localized prostatic cancer.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (from 1950), and EMBASE (from 1980) were searched in June 2010 as well as online trials registers and reference lists of reviews.

SELECTION CRITERIA

Randomized, controlled trials comparing LDR-BT versus RP, EBRT, and NPT in men with clinically localized prostate cancer.

DATA COLLECTION AND ANALYSIS

Data on study methods, participants, treatment regimens, observation period and outcomes were recorded by two reviewers independently.

MAIN RESULTS

We identified only one RCT (N = 200; mean follow up 68 months). This trial compared LDR-BT and RP. The risk of bias was deemed high. Primary outcomes (overall survival, cause-specific mortality, or metastatic-free survival) were not reported. Biochemical recurrence-free survival at 5 years follow up was not significantly different between LDR-BT (78/85 (91.8%)) and RP (81/89 (91.0%)); P = 0.875; relative risk 0.92 (95% CI: 0.35 to 2.42).For severe adverse events reported at 6 months follow up, results favored LDR-BT for urinary incontinence (LDR-BT 0/85 (0.0%) versus RP 16/89 (18.0%); P < 0.001; relative risk 0) and favored RP for urinary irritation (LDR-BT 68/85 (80.0%) versus RP 4/89 (4.5%); P < 0.001; relative risk 17.80, 95% CI 6.79 to 46.66). The occurrence of urinary stricture did not significantly differ between the treatment groups (LDR-BT 2/85 (2.4%) versus RP 6/89 (6.7%); P = 0.221; relative risk 0.35, 95% CI: 0.07 to 1.68). Long-term information was not available.We did not identify significant differences of mean scores between treatment groups for patient-reported outcomes function and bother as well as generic health-related quality of life.

AUTHORS' CONCLUSIONS

Low-dose rate brachytherapy did not reduce biochemical recurrence-free survival versus radical prostatectomy at 5 years. For short-term severe adverse events, low-dose rate brachytherapy was significantly more favorable for urinary incontinence, but radical prostatectomy was significantly more favorable for urinary irritation. Evidence is based on one RCT with high risk of bias.

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

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

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

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

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

Combined curative radiotherapy including HDR brachytherapy and androgen deprivation in localized prostate cancer: a prospective assessment of acute and late treatment toxicity

Self-reported symptoms including urinary, bowel and sexual side effects were investigated prospectively at multiple assessment points before and after combined radiotherapy of prostate cancer including HDR brachytherapy and neoadjuvant androgen deprivation therapy. Between April 2000 and June 2003, patients with predominantly advanced localized prostate tumours subjected to this treatment were asked before treatment and on follow-up visits to complete a questionnaire covering urinary, bowel and sexual problems. The mainly descriptive analyses included 525 patients, responding to at least one questionnaire before or during the period 2-34 months after radiotherapy. Adding androgen deprivation before radiotherapy significantly worsened sexual function. During radiotherapy, urinary, bowel and sexual problems increased and were reported at higher levels up to 34 months, although there seemed to be a general tendency to less pronounced irritative bowel and urinary tract symptoms over time. No side effects requiring surgery were reported. Classic late irradiation effects such as mucosal bleeding were demonstrated mainly during the second year after therapy, but appear less pronounced in comparison with dose escalated EBRT series. In conclusion, despite the high radiation dose given, the toxicity seemed comparable with that of other series but long term (5-10 years) symptom outcome has to be determined.

External beam radiotherapy for prostate cancer patients on anticoagulation therapy: how significant is the bleeding toxicity?

PURPOSE

To characterize the bleeding toxicity associated with external beam radiotherapy for prostate cancer patients receiving anticoagulation (AC) therapy.

METHODS AND MATERIALS

The study cohort consisted of 568 patients with adenocarcinoma of the prostate who were treated with definitive external beam radiotherapy. Of these men, 79 were receiving AC therapy with either warfarin or clopidogrel. All patients were treated with three-dimensional conformal radiotherapy or intensity-modulated radiotherapy. Bleeding complications were recorded during treatment and subsequent follow-up visits.

RESULTS

With a median follow-up of 48 months, the 4-year actuarial risk of Grade 3 or worse bleeding toxicity was 15.5% for those receiving AC therapy compared with 3.6% among those not receiving AC (p < .0001). On multivariate analysis, AC therapy was the only significant factor associated with Grade 3 or worse bleeding (p < .0001). For patients taking AC therapy, the crude rate of bleeding was 39.2%. Multivariate analysis within the AC group demonstrated that a higher radiotherapy dose (p = .0408), intensity-modulated radiotherapy (p = 0.0136), and previous transurethral resection of the prostate (p = .0001) were associated with Grade 2 or worse bleeding toxicity. Androgen deprivation therapy was protective against bleeding, with borderline significance (p = 0.0599). Dose-volume histogram analysis revealed that Grade 3 or worse bleeding was minimized if the percentage of the rectum receiving >or=70 Gy was <10% or the rectum receiving >or=50 Gy was <50%.

CONCLUSION

Patients taking AC therapy have a substantial risk of bleeding toxicity from external beam radiotherapy. In this setting, dose escalation or intensity-modulated radiotherapy should be used judiciously. With adherence to strict dose-volume histogram criteria and minimizing hotspots, the risk of severe bleeding might be reduced.

Physical models and simpler dosimetric descriptors of radiation late toxicity

Predicting radiation damage to specific organs is becoming ever more challenging with the use of intensity-modulated beams, nonuniform dose distributions, partial organ irradiation, and interpatient and even intraorgan variations in radiation sensitivity. Data-based physical models can be of use in summarizing complicated dose-volume data to help describe clinical outcomes and ultimately aid in the prediction of clinical toxicity. This article attempts to provide a brief overview of the use of normal tissue complication probability (NTCP) models and other simple dose/volume metrics to describe a few clinically significant complications (either frequent or serious) associated with radiation therapy of the head and neck, thorax, and abdominal-pelvic regions. Specifically, it reviews the application of these methods for late toxicities of the parotid, lung, heart, spinal cord, liver, and rectum. It focuses on organ-specific NTCP parameters as well as simple dosimetric descriptors that might be used to help treatment plan evaluation in clinical practice.

When should the seminal vesicles be included in the target volume in prostate radiotherapy?

External beam radiotherapy to the prostate and seminal vesicles as a radical treatment for prostate cancer can result in a significant dose being delivered to the rectum. This can be reduced if the target volume includes the prostate only. Using a Medline search, published studies are reviewed to show that the risk of seminal vesicle involvement can be accurately predicted using readily available pre-treatment parameters. We recommend when to exclude the seminal vesicles from a target volume, and the proportion of seminal vesicles that should be included in a target volume in higher risk patients.

Quantification des mouvements prostatiques lors de l'irradiation prostatique

Decrease treatment uncertainties is one of the most important challenge in radiation oncology. Numerous techniques are available to quantify prostate motion and visualise prostate location day after day before each irradiation: CT-scan, cone-beam-CT-Scan, ultrason, prostatic markers... The knowledge of prostate motion is necessary to define the minimal margin around the target volume needed to avoid mispositioning during treatment session. Different kind of prostate movement have been studied and are reported in the present work: namely, those having a large amplitude extending through out the whole treatment period on one hand; and those with a shorter amplitude happening during treatment session one the other hand. The long lasting movement are mostly anterior-posterior (3 mm standard deviation), secondary in cranial-caudal (1-2 mm standard deviation) and lateral directions (0.5-1 mm standard deviation). They are mostly due to the rectal state of filling and mildly due to bladder filling or inferior limbs position. On the other hand, the shorter movement that occurs during the treatment session is mostly variation of position around a steady point represented by the apex. Ones again, the rectal filling state is the principle cause. This way, during the 20 minutes of a treatment session, including the positioning of the patient, a movement of less than 3 mm could be expected when the rectum is empty. Ideally, real time imaging tools should allow an accurate localisation of the prostate and the adaptation of the dosimetry before each treatment session in a time envelope not exceeding 20 minutes.

PTV margin for dose escalated radiation therapy of prostate cancer with daily on-line realignment using internal fiducial markers: Monte Carlo approach and dose population histogram (DPH) analysis

Using internal fiducial markers and electronic portal imaging (EPI) to realign patients has been shown to significantly reduce positioning uncertainties in prostate radiation treatment. This creates the possibility of decreasing the planning target volume (PTV) margin added on the clinical target volume (CTV), which in turn may allow for dose escalation. We compared the outcome of two plans: 70 Gy/35 fx, 10‐mm PTV margin without patient realignment (Reference Plan) and 78 Gy/39 fx, 5‐mm PTV margin with patient realignment (Escalated Plan). Four‐field‐oblique (gantry angles 35°, 90°, 270°, 325°) beam arrangement was used. Monte Carlo code was used to simulate the daily organ motion. Dose to each organ was calculated. Tumor control probability (TCP) and the effective dose to critical organs (Deff) were calculated using the biologically normalized dose‐volume histograms. By comparing the biological factors, we found that the prescription dose can be escalated to 78 Gy/39 fx with a 5‐mm PTV margin when using internal fiducial markers and EPI. Based on the available dose‐response data for intermediate risk prostate patients, this will result in a 20% increase of local control and significantly reduced rectal complications provided that less serial dose‐volume behavior of rectum is proven.

PACS number: 87.50.‐a

Radiation therapy in the management of locally advanced prostate cancer

Locally advanced prostate cancer generally refers to those patients with clinical stages T3-4 disease. Patients with locally advanced cancer frequently are included in clinical trials that examine treatment for patients at high risk for relapse based on presenting prostate-specific antigen, high Gleason score, or advanced clinical stage. There is a growing body of evidence that suggests that men with localized prostate cancer benefit from high-dose radiation therapy delivered with three-dimensional conformal radiation therapy, intensity-modulated radiation therapy, or proton beam therapy. Most importantly, neoadjuvant and adjuvant androgen-deprivation therapy have significantly improved outcomes in men with locally advanced or high-risk prostate cancer. Although questions remain regarding the optimal timing and duration of adjuvant hormonal therapy, a combination of long-term androgen deprivation started before radiation therapy and continued for 2 years represents a North American standard of care for this patient population.

Patient tolerance of rectal balloons in conformal radiation treatment of prostate cancer

PURPOSE

To evaluate patient tolerance of intrarectal balloons used during conformal prostate irradiation.

METHODS AND MATERIALS

A retrospective analysis was performed on 3,561 patients who underwent conformal radiation for prostate cancer. Therapy consisted of proton irradiation of the prostate and seminal vesicles and X-ray treatment of the pelvis when warranted. The number of treatments in which the balloon was tolerated was recorded. Results were stratified according to method of irradiation (protons alone vs. combined proton/X-ray) and method of planning (2D vs. 3D planning of X-ray fields in patients undergoing combination treatment).

RESULTS

Of all the patients evaluated, 3,474 (97.6%) tolerated the balloon throughout treatment; 87 (2.4%) declined the balloon for 1 or more treatments and tolerated the balloon for 85.5% of their treatments. Chi-square analysis revealed a significant tolerance advantage in those who received protons alone compared with combination treatment (99.5% vs. 95.7%; p < 0.001). In patients undergoing combination treatment, chi-square analysis did not reveal significant tolerance differences in patients undergoing 3D vs. 2D planning for pelvic X-ray fields (95.74% vs. 95.72%; p = 0.990).

CONCLUSIONS

Intrarectal balloons are well tolerated over a course of conformal prostate irradiation.

Internal fiducial markers can assist dose escalation in treatment of prostate cancer: result of organ motion simulations

Use of internal fiducial markers and electronic portal imaging (EPI) to realign patients has been shown to significantly reduce positioning uncertainties in prostate radiation treatment. This creates the possibility of improving the treatment by decreasing the planning target volume (PTV) margin added to the clinical target volume (CTV), which in turn may allow dose escalation. Conformal treatment plans for three prostate cancer patients were evaluated by using different PTV margins with dose prescription of 70 Gy/35 fr initially. Two beam arrangements, 4-field-box (4FB) and 4-field-oblique (4FO), were used. Then, two dose escalation schemes, 74 Gy and 78 Gy, with tighter PTV margins, were chosen from the first simulation and were tested. A Monte Carlo model was developed to simulate the daily geometric uncertainty and calculate the dose to each organ. After the whole treatment, dose-volume histograms were produced and tumour control probability, prostate equivalent uniform dose and the effective dose to critical organs were calculated. By comparing these radiobiological metrics, optimized dose escalation schemes were found. The results show that using internal fiducial markers and EPI, the prescription dose can be escalated to 78 Gy/39 fr with a 4 mm PTV margin. Based on the available dose-response data for intermediate risk prostate patients, this is estimated to result in a 20% increase of local control and significantly reduced rectal complications.

Cancer of the prostate

Prostate carcinoma, with about 190,000 new cases occurring each year (15% of all cancers in men), is the most frequent cancer among men in northern and western Europe. Causes of the disease are essentially unknown, although hormonal factors are involved, and diet may exert an indirect influence; some genes, potentially involved in hereditary prostate cancer (HPC) have been identified. A suspect of prostate cancer may derive from elevated serum prostate-specific antigen (PSA) values and/or a suspicious digital rectal examination (DRE) finding. For a definitive diagnosis, however, a positive prostate biopsy is requested. Treatment strategy is defined according to initial PSA stage, and grade of the disease and age and general conditions of the patient. In localized disease, watchful waiting is indicated as primary option in patients with well or moderately differentiated tumours and a life expectancy <10 years, while radical prostatectomy and radiotherapy (with or without hormone-therapy) could be appropriate choices in the remaining cases. Hormone-therapy is the treatment of choice, combined with radiotherapy, for locally advanced or bulky disease and is effective, but not curative, in 80-85% of the cases of advanced disease. Patients who develop a hormone-refractory prostate cancer disease (HRPC) have to be evaluated for chemotherapy because of the recent demonstration of improved overall survival (2-2.5 months) and quality of life with docetaxel in more than 1,600 cases.

Prostate gland motion assessed with cine-magnetic resonance imaging (cine-MRI)

PURPOSE

To quantify prostate motion during a radiation therapy treatment using cine-magnetic resonance imaging (cine-MRI) for time frames comparable to that expected in an image-guided radiation therapy treatment session (20-30 min).

MATERIALS AND METHODS

Six patients undergoing radiation therapy for prostate cancer were imaged on 3 days, over the course of therapy (Weeks 1, 3, and 5). Four hundred images were acquired during the 1-h MRI session in 3 sagittal planes through the prostate at 6-s intervals. Eleven anatomic points of interest (POIs) have been used to characterize prostate/bony pelvis/abdominal wall displacement. Motion traces and standard deviation for each of the 11 POIs have been determined. The probability of displacement over time has also been calculated.

RESULTS

Patients were divided into 2 groups according to rectal filling status: full vs. empty rectum. The displacement of POIs (standard deviation) ranged from 0.98 to 1.72 mm for the full-rectum group and from 0.68 to 1.04 mm for the empty-rectum group. The low standard deviations in position (2 mm or less) would suggest that these excursions have a low frequency of occurrence. The most sensitive prostate POI to rectal wall motion was the mid-posterior with a standard deviation of 1.72 mm in the full-rectum group vs. 0.79 mm in the empty-rectum group (p = 0.0001). This POI has a 10% probability of moving more than 3 mm in a time frame of approximately 1 min if the rectum is full vs. approximately 20 min if the rectum is empty.

CONCLUSION

Motion of the prostate and seminal vesicles during a time frame similar to a standard treatment session is reduced compared to that reported in interfraction studies. The most significant predictor for intrafraction prostate motion is the status of rectal filling. A prostate displacement of <3 mm (90%) can be expected for the 20 min after the moment of initial imaging for patients with an empty rectum. This is not the case for patients presenting with full rectum. The determination of appropriate intrafraction margins in radiation therapy to accommodate the time-dependent uncertainty in positional targeting is a topic of ongoing investigations for the on-line image guidance model.

The efficacy of conventional external beam, three-dimensional conformal, intensity-modulated, particle beam radiation, and brachytherapy for localized prostate cancer

Technologic advances in radiation treatment planning and delivery have generated popular interest in the different radiation therapy techniques used in treating patients with localized prostate cancer. Throughout the past decade, high-energy (> 4 MV) linear accelerators have largely replaced Cobalt machines in external beam radiation therapy (EBRT) delivery. Conventional EBRT has been used to treat prostate cancer successfully since the 1950s. By switching to computed tomography-based planning, three-dimensional conformal radiation therapy provides better relative conformality of dose than does conventional EBRT. Intensity-modulated radiation therapy (IMRT) has further refined dose conformality by spreading the low-dose region to a larger volume. However, the potential long-term risks of larger volumes of normal tissues receiving low doses of radiation in IMRT are unknown. Particle-beam radiation therapy offers unique dose distributions and characteristics with higher relative biologic effect and linear energy transfer. Transperineal prostate brachytherapy offers the shortest treatment time with equivalent efficacy without significant risk of radiation exposure. The addition of hormonal therapy to radiation therapy has been shown to improve the outcome of radiation therapy.

Treatment planning evaluation of non-coplanar techniques for conformal radiotherapy of the prostate

BACKGROUND AND PURPOSE

To evaluate the benefit of using non-coplanar treatment plans for irradiation of two different clinical treatment volumes: prostate only (PO) and the prostate plus seminal vesicles (PSV).

MATERIAL AND METHODS

An inverse planning algorithm was used to produce three-field, four-field, five-field and six-field non-coplanar treatment plans without intensity-modulation in ten patients. These were compared against a three-field coplanar plan. A dose of 74 Gy was prescribed to the isocentre. Plans were compared using the minimum dose to the planning target volume (PTV), maximum dose to the small bowel, and irradiated volumes of rectum, bladder and femoral head. Biological indices were also evaluated.

RESULTS

For the PO group, volume of rectum irradiated to 60 Gy (V(60)) was 22.5+/-3.7% for the coplanar plan, and 21.5+/-5.3% for the five-field non-coplanar plan, which was the most beneficial (p=0.3). For the PSV group, the five-field non-coplanar plan was again the most beneficial. Rectal V(60) was in this case reduced from 41.5+/-10.4% for the coplanar plan to 35.2+/-9.3% for the non-coplanar plan (p=0.02).

CONCLUSIONS

The use of non-coplanar beams in conformal prostate radiotherapy provides a small increase in rectal sparing, more significantly with PSV volumes than for PO volumes.

Comparison of external radiation therapy vs radical prostatectomy in lymph node positive prostate cancer patients

INTRODUCTION

Treatment options for lymph node positive prostate cancer are limited. We retrospectively compared patients who underwent external radiotherapy (ERT) to patients treated by radical prostatectomy (RPX).

MATERIALS AND METHODS

A total of 102 lymph node positive patients from the RPX series at Ulm University were evaluated. In all, 76 patients received adjuvant androgen withdrawal as part of their primary treatment. In the ERT group, 44 patients were treated at the University of Michigan using a fractionated regimen. Of these, 21 patients received early adjuvant hormonal therapy. Patients with neoadjuvant therapy before RPX or ERT were excluded.

RESULTS

In the RPX group, PSA nadir (nadir < or = 0.2 vs > 0.2 ng/ml) showed a strong association with outcome. In the ERT group, pretreatment PSA was an independent predictor of outcome (P = 0.04) and patients with adjuvant hormonal therapy had a significant longer recurrence-free interval compared to patients without adjuvant therapy (P = 0.004). Comparing only patients with adjuvant hormonal treatment after cancer-specific therapy, the ERT-treated patients had a borderline longer PSA recurrence-free survival time compared to the RPX-treated patients (P = 0.05).

CONCLUSIONS

In case of positive lymph nodes, RPX and ERT might be considered and need to be explained to the patient. For future treatment decisions, the presented findings and a potential survival benefit need to be evaluated in a larger prospective setting.

Quality assurance of the 22961 EORTC trial. A phase III study of the optimal combination of hormonal adjuvant treatment by LHRH analogue and radiation therapy for the management of locally advanced prostate cancer: the dummy run

PURPOSE

The EORTC trial 22961, opened in 1997, was designed to investigate the optimal combination of hormonal adjuvant treatment by LHRH analogue and radiation therapy for the management of locally advanced prostate cancer. A dummy run was established to assess centre compliance to the radiotherapy protocol.

MATERIALS AND METHODS

Medical and anatomical data obtained from 37 CT slices (5mm thickness) of an eligible patient were sent to 19 participating centres, which were asked to complete a questionnaire according to their practice and plan a theoretical radiotherapy treatment. The Planning Target Volume 1 (PTV1) should include prostate, seminal vesicles, internal iliac lymph nodes and inferior part of common iliac lymph nodes (extended pelvic fields). Centres which usually irradiate with small pelvic fields (N0 patients), were allowed to include the prostate, seminal vesicles and internal iliac lymph nodes plus a safety margin of 2 cm. For the Planning Target Volume 2 (PTV2), a safety margin of 1.5 to 2 cm should be around the prostate and seminal vesicles. Checks included patient positioning, treatment simulation, target volume definition, treatment set-up and clinical controls during treatment.

RESULTS

Eleven institutions with actual 81% of patients' accrual in the protocol have responded. All centres used a supine treatment position and positioning lasers for the set-up, while 73 and 45% of the centres performed cystograms and used rectal contrast, respectively. Among the participating centres, 45% and 55% used blocks and MLC, respectively, to treat patients. Extended pelvic fields in terms of PTV1 were used by 63% of the centres. The remaining centres treated a small PTV1 with a 10-20 mm margin around to CTV1. All centres defined PTV2 according to protocol guidelines. Doses to PTV1 and PTV2 were correctly prescribed. It was difficult to assess the treated volumes due to a lack of standardisation in DVH calculations.

CONCLUSION

In general, centres participating in the dummy run adhered to the guidelines. The dummy run enhances the reliability of the conclusions of the trial.

Status of postmastectomy radiotherapy in the United States: A patterns of care study

PURPOSE

The Patterns of Care Study performed this first known practice survey to establish a national profile of the delivery of postmastectomy radiotherapy (RT) in operable breast cancer.

METHODS AND MATERIALS

A Patterns of Care Study research associate collected data from 55 randomly selected institutions. The survey data included 132 items describing the patient, pathologic features, and treatment course for patients with clinical Stage I, II, and IIIA breast cancer undergoing postmastectomy RT in 1998 and 1999. A multivariate analysis was performed to determine the impact of tumor factors and type of treatment facility on the radiation fields used.

RESULTS

A weighted sample size of 13,720 was obtained from a sampling of 405 patient records. The mean tumor size was 3.5 cm, and the mean number of axillary nodal metastases was 4.55. Lymphatic vascular invasion was noted in 34%, microscopic skin or dermal lymphatic invasion in 16%, positive or close margins in 36%, and extracapsular nodal extension in 23%. Radiotherapy included the chest wall in all cases and the regional nodes in 78%. When nodal RT was delivered, it included a supraclavicular field, supplemental axillary field, and/or an internal mammary field in 98%, 46%, and 23% of cases, respectively. Chest wall and supraclavicular RT was delivered in >90% of instances with 6-MV photons to doses between 45 and 50 Gy. More variation was seen in the delivery of the axillary and internal mammary RT. On multivariate analysis, the presence of four or more positive nodes and treatment at a large-volume facility were the factors most frequently associated with the use of regional radiation fields.

CONCLUSION

This Patterns of Care Study survey has demonstrated that breast cancer patients undergoing postmastectomy RT in 1998 and 1999 had a high proportion of factors associated with an increased risk of locoregional failure. The practice patterns established in this study provide a baseline for comparison with future survey results.

Impact of mean rectal dose on late rectal bleeding after conformal radiotherapy for prostate cancer: Dose–volume effect

PURPOSE

To identify the clinical and dosimetric factors predictive of a greater risk of Grade 2 or worse late rectal bleeding in patients with localized prostate cancer treated with three-dimensional conformal radiotherapy in a prospective dose-escalation study.

METHODS AND MATERIALS

We performed a retrospective analysis of the clinical records and dose-volume histograms of 107 patients with Stage T1c-T3 prostate cancer treated at our institution with three-dimensional conformal radiotherapy who had a minimal follow-up of 1 year. Of the 107 patients, 21 were treated at dose level 1 (70.0 Gy), 57 at dose level 2 (72.0 Gy), and 29 at dose level 3 (75.6 Gy). The mean International Commission on Radiation Units and Measurements reference dose was 76.5 Gy (range, 69.8-82.6 Gy).

RESULTS

The 4-year actuarial incidence of Grade 2 or worse late rectal bleeding was 7.7% +/- 2.5%. The results of the multivariate analysis indicated that the mean rectal dose (rectal D(mean); p = 0.003) and the percentage of rectum receiving >60 Gy (Vr(60); p = 0.002) correlated with Grade 2 or worse rectal bleeding. The receiver operating characteristic curve analysis showed that this logistic regression model using both Vr(60) and rectal D(mean) had good reliability to predict the risk of late rectal bleeding. The area under the curve for Vr(60) and rectal D(mean) was 0.889 and 0.892, respectively.

CONCLUSION

The results of the present study provide clear evidence of a dose-volume effect and the importance of intermediate doses (60.0 Gy) on the risk of rectal bleeding at this prescription dose level. On the basis of these results, new constraints have been implemented in our institution to keep the risk of developing Grade 2 rectal bleeding reasonably low (rectal D(mean) 50.0 Gy and Vr(60) 42%).

Hyperbaric oxygen therapy in the treatment of radio-induced lesions in normal tissues: a literature review

Late complications are one of the major factors limiting radiotherapy treatment, and their treatment is not codified. Hyperbaric oxygen (HBO) has been used in combination with radiotherapy for over half a century, either to maximise its effectiveness or in an attempt to treat late complications. In this latter case, retrospective trials and case reports are prevailing in literature. This prompted European Society for Therapeutic Radiotherapy and Oncology and European Committee for Hyperbaric Medicine to organise a consensus conference in October 2001, dealing with the HBO indications on radiotherapy for the treatment and prevention of late complications. This updated literature review is part of the documents the jury based its opinion on. A systematic search was done on literature from 1960 to 2004, by only taking into account the articles that appeared in peer review journals. Hyperbaric oxygen treatment involving complications to the head and neck, pelvis and nervous system, and the prevention of complications after surgery in irradiated tissues have been studied. Despite the small number of controlled trials, it may be indicated for the treatment of mandibular osteoradionecrosis in combination with surgery, haemorrhagic cystitis resistant to conventional treatments and the prevention of osteoradionecrosis after dental extraction, whose level of evidence seems to be the most significant though randomised trials are still necessary. The other treatment methods are also outlined for each location.

Impact of neoadjuvant androgen ablation and other factors on late toxicity after external beam prostate radiotherapy

PURPOSE

To evaluate the late toxicity profile of prostate cancer patients treated with external beam radiotherapy, to investigate the possible risk factors for late toxicity, and to determine whether neoadjuvant androgen ablation (NAA) is a factor.

METHODS AND MATERIALS

The study population consisted of 1192 patients with > or =24 months' follow-up. Late GI and GU toxicities were scored with a modified Radiation Therapy Oncology Group/Subjective, Objective, Management, and Analytic scale. All patients were treated with external beam radiotherapy (52.5 Gy in 20 fractions to 72 Gy in 36 fractions), using either conventional or three-dimensional conformal techniques. Of the 1192 patients, 40% received NAA (median 5 months). Risk factors investigated on multivariate analysis were age, past medical history, use of pelvic fields, dose, fractionation, use and duration of neo- and adjuvant androgen ablation, and acute toxicity (Grade 2 or greater).

RESULTS

The median follow-up for the group was 49 months (range 24-105). The incidence of late Grade 2-3 GI or GU toxicity was 30% at 5 years (GI 12% and GU 20%). The incidence of late Grade 3 GI or GU toxicity was 8% at 5 years (GI 2.7% and GU 5.5%). No Grade 4 toxicity occurred. The risk factors of significance in relation to the development of late Grade 3 GU toxicity were coexisting GU disease (p = 0.02), prior transurethral resection of the prostate or transurethral resection of bladder tumor (p <0.0001), and presence of acute GU toxicity (p = 0.012). For late Grade 3 GI toxicity, short-term (< or =2 months) NAA (p = 0.0002) and coexisting GI disease (p = 0.017) were risk factors.

CONCLUSION

Short-term (< or =2 months) NAA, but not longer durations of NAA, increases the risk of developing Grade 3 GI late toxicity. The possible mechanism of this phenomenon is unclear.

Clinical feasibility study for the use of implanted gold seeds in the prostate as reliable positioning markers during megavoltage irradiation

BACKGROUND AND PURPOSE

The aim of this study was to assess the feasibility of using gold seed implants in the prostate for position verification, using an a-Si flat panel imager as a detector during megavoltage irradiation of prostate carcinoma. This is a study to guarantee positioning accuracy in intensity-modulated radiotherapy.

METHODS AND MATERIALS

Ten patients with localized prostate carcinoma (T2-3) received between one and three fiducial gold markers in the prostate. All patients were treated with 3-D conformal radiotherapy with an anterior-posterior (AP) and two lateral wedge fields. The acute gastrointestinal (GI) and genitourinary (GU) toxicities were scored using common toxicity criteria scales (CTC). Using three consecutive CT scans and portal images obtained during the treatment we have studied the occurrence of any change in prostate shape (deformation), seed migration and the magnitude of translations and rotations of the prostate.

RESULTS

We observed no acute major complications for prostate irradiation regarding the seed implantation. The maximum acute GU toxicity grade 2 (dysuria and frequency) was observed in seven patients during the treatment. The maximum grade 2 (diarrhoea) was scored in two patients regarding the acute GI toxicities. No significant prostate deformation could be detected in the consecutive CT scans. It appeared that the distances between the markers only slightly changed during treatment (S.D. 0.5 mm). Random prostate translations were (1 S.D.) 2.1, 3.2 and 2.2 mm in the lateral (LR), AP and cranial-caudal (CC) directions, respectively, whereas systematic translations were 3.3, 4.8 and 3.5 mm in the LR, AP and CC directions, respectively. Random prostate rotations were (1 S.D.) 3.6, 1.7 and 1.9 degrees around the LR, AP and CC axis, respectively, whereas systematic rotations were 4.7, 2.0 and 2.7 degrees around the LR, AP and CC axis, respectively.

CONCLUSIONS

We found that the fiducial gold seeds are a safe and appropriate device to verify and correct the position of prostate during megavoltage irradiation. The amount of seed migration and prostate deformation is far below our present tumour delineation accuracy.

Localized prostate cancer: radiation or surgery?

The treatment of localized prostate cancer remains controversial because of the lack of conclusive well-controlled or randomized studies comparing outcomes of radiotherapy to outcomes of radical prostatectomy. A comparison of different therapies should include issues of cancer control, morbidity, quality of life (QOL), salvage of primary treatment failures, late effects, and cost. The available data suggest that these two modalities provide similar rates of cancer control at 10 years, and that except for the youngest patients, choice of therapy should be based on toxicity and QOL issues.

Interim report of toxicity from 3D conformal radiation therapy (3D-CRT) for prostate cancer on 3DOG/RTOG 9406, level III (79.2 Gy)

PURPOSE

A prospective Phase I dose escalation study was conducted to determine the maximally tolerated radiation dose in men treated with three-dimensional conformal radiotherapy (3D-CRT) for localized prostate cancer. This is a preliminary report of toxicity at Level III (79.2 Gy) on 3D Oncology Group/Radiation Therapy Oncology Group (RTOG) 9406.

METHODS AND MATERIALS

Between November 26, 1996 and October 1, 1998, 173 patients with clinically organ-confined prostate cancer (T1 and T2) were accrued to a Level III dose of 79.2 Gy. One hundred sixty-nine patients were available for analysis of toxicity. Patients were registered to two groups according to the risk of seminal vesicle invasion (SVI) on the basis of presenting PSA and Gleason score. Group 1 patients had a calculated risk of SVI <15%, and Group 2 patients had a risk of SVI > or = 15%. For Group 1 patients, the planning target volume (PTV) margins were 5-10 mm around the prostate only. For Group 2 patients, the same margins were applied to the prostate and seminal vesicles (PTV(1)) for the initial 55.8 Gy; then treatment volume was reduced to the prostate only (PTV(2)). To reduce the rectal dose on dose Level III, the minimum PTV dose was limited to 73.8 Gy, whereas the minimum gross target volume dose was 79.2 Gy, both in 44 fractions. The incidence of > or = 3 Grade late effects was compared to that in a similar group of patients treated on RTOG 7506 and 7706 studies.

RESULTS

Acute tolerance to 79.2 Gy was excellent with no patients experiencing > or = Grade 3 acute toxicity. The acute toxicity rate was comparable to that reported for previous lower dose levels. With the median follow-up of 3.3 years (range: 0.4-4.4 years), a total of 4 patients (2.4%) experienced Grade 3 late toxicity, three cases of which were related to the bladder, and one related to the rectum. There were no Grade 4 or 5 late complications noted during the period of observation. These results are also comparable to those reported at dose Levels I and II. The expected incidence of > or = 3 Grade 3 late toxicity was calculated using historical data from two previous RTOG prostate cancer trials, 7506 and 7706. The calculated risk accounted for the difference in follow-up duration between patients in this study and the historical experience. The observed rate of > or = Grade 3 late effects for Group 1 (two cases) is significantly lower (p = 0.0002) than the 17.6 cases that would have been expected from the historical control. The observed rate for Group 2 (two cases) was also significantly lower (p = 0.0037) than the 12.1 cases expected.

CONCLUSION

Based on excellent tolerance of 3D-CRT for stages T1 and T2 prostate cancer, further biological dose escalation has been pursued to Levels IV and V, 74 Gy and 78 Gy, respectively, at 2 Gy per day, in an attempt to reduce the total treatment duration. This trial has closed. A Phase III comparative RTOG trial is being developed to determine whether high-dose 3D-CRT improves efficacy.

Primary radiation therapy for localized prostate cancer

Prostate cancer in men is similar to breast cancer in women; both cancers rank first, respectively, in incidence and are normally responsive to radiation therapy. In addition, advances in mammography help detect earlier breast cancers, and the development and refinement of prostatic specific antigen (PSA) has resulted in early detection of low-stage localized prostate cancers. This has generated debate over the proper management of localized prostate cancer. While there have not been any controlled, prospective, randomized trials of sufficient power to compare the various local therapies, based on the current available data, the three commonly used local modalities, surgery, and external beam radiation therapy and brachytherapy (radioactive seed implant), have similar efficacy controlling the disease up to 10 years in many patients. Technological advances in treatment delivery and planning have improved the treatment of prostate cancer with external-beam radiotherapy using three-dimensional conformal radiotherapy (3DCRT), ultrasound-guided transperineal implant, or intensity-modulated radiotherapy (IMRT), as well as proton or neutron beam based therapies.

Evaluation and characterization of parallel plate microchamber's functionalities in small beam dosimetry

A parallel plate microchamber (PPMC) has been designed to specifically address the problems of small beam dosimetry. The chamber's extremely small volume and tissue equivalency theoretically make it possible for the chamber to perform an ideal measurement for small field dosimetry. Results show the PPMC to be a simple and reproducible detector for the measurements of total scattering factors, percentage depth doses, and off-axis ratios. Even with its unique geometry, the PPMC requires a correction factor when measuring total scatter factors of fields smaller than 2.5 cm in diameter. Results obtained with the PPMC for fields greater than 2.5 cm diameter closely match those of alternative measurement modalities. The exceptionally small volume of the chamber increases the effect of radiation-induced cable currents. With careful experimental technique, this problem can be resolved. Monte Carlo simulations of a Sun Nuclear QED low build-up diode were done to show that no correction factor is needed for the diode in measuring total scatter factors of small fields. However, the scattering factors measured with the PPMC should be corrected for cone fields smaller than 2.5 cm in diameter. With the correction factor, the scattering factor obtained with the PPMC matches that with the QED diode within 0.7%. The percent depth dose data taken with the PPMC for a 40 x 40 cm2 field closely matches that taken with the PTW chamber with the largest deviation being approximately 1.2% at a depth of 30 cm. For a measurement of the off-axis ratio with stereotactic cones of diameter 1.25 and 4.0 cm, the data obtained with the PPMC have a good agreement (less than 0.5% difference) with the film measurement.

Three-Dimensional Conformal Therapy Versus Standard Radiation Therapy in Localized Carcinoma of Prostate: An Update

This study updates technical principles and results of 3-dimensional conformal radiation therapy (3D-CRT) in localized carcinoma of the prostate. Between January 1992 and December 1999, 312 patients were treated with 3D-CRT and 135 patients were treated with bilateral arcs standard radiation therapy (SRT) alone for clinical stage T1b-c or T2 histologically confirmed prostate cancer. None of these patients received hormonal therapy. Mean follow-up for patients in the 3D-CRT group was 3.2 years (range, 2-5.9 years) and for SRT patients, 4.7 years (range, 4-7 years). For 3D-CRT, 7 intersecting fields were used (cerrobend blocking or multileaf collimation) to deliver 68-74 Gy to the prostate. Standard radiation therapy consisted of bilateral 120 degree rotational arcs, with portals using 2-cm margins around the prostate to deliver 68-70 Gy to the prostate. The criterion for chemical disease-free survival was a postirradiation prostate-specific antigen (PSA) value following the American Society for Therapeutic Radiology and Oncology guidelines. Symptoms during treatment were quantitated weekly, and late effects were assessed every 4-6 months. Dose-volume histograms showed a two-thirds reduction with 3D-CRT in normal bladder or rectum receiving > or = 70 Gy with 3D-CRT. Higher 5-year chemical disease-free survival was observed with 3D-CRT (75%; for T1b-c and 79%; for T2 tumors) compared with SRT (61% and 65%, P = 0.01 and P = 0.12, respectively). There was no statistically significant difference in chemical disease-free survival in patients with Gleason score of < or = 4 (P = 0.85), but, with Gleason score of 5-7, the 5-year survival rates were 83% with 3D-CRT and 59% with SRT (P < or = 0.01). In 245 patients with pretreatment PSA of < or = 10 ng/mL treated with 3D-CRT, the chemical disease-free rate was 80% versus 72% in 98 patients treated with SRT (P = 0.21). In patients with PSA of 10.1-20 ng/mL, the chemical disease-free survival rate for 50 patients treated with 3D-CRT was 71% compared with 43% for 20 patients treated with SRT (P = 0.02). The corresponding values were 59% and 16%, respectively, for patients with PSA levels > 20 ng/mL (P = 0.09). On multivariate analysis, the most important prognostic factors for chemical failure were pretreatment PSA (P = 0.004), nadir PSA (P = 0.001), and 3D-CRT technique (P = 0.012). Moderate dysuria was reported by 2%-5% of patients treated with 3D-CRT in contrast to 6%-9% of patients treated with SRT. The incidence of moderate loose stools or diarrhea, usually after the fourth week of treatment, was 3%-5% in the 3D-CRT patients and 8%-19% in the SRT group. Late intestinal grade 2 morbidity (proctitis or rectal bleeding) was 1% in the 3D-CRT group in contrast to 7% in SRT patients. The 3D-CRT spares more normal tissues, yields higher chemical disease-free survival, and results in less treatment morbidity than SRT in treatment of stage T1-T2 prostate cancer. Follow-up at > or = 10 years is needed to confirm these observations.

A pilot study of topical intrarectal application of amifostine for prevention of late radiation rectal injury

PURPOSE

Clinical symptomatic late injury to the rectal wall occurs in about one-third of patients with prostate cancer treated with external beam irradiation. Reducing the physical dose to the anterior rectal wall without a similar reduction in the posterior peripheral zone is difficult because of the proximity of the prostate to the anterior rectal wall. On the basis of our previous observations in an animal model that intrarectal application of amifostine resulted in very high concentrations of amifostine and its active metabolite WR-1065 in the rectal wall, a Phase I dose-escalation clinical trial was undertaken.

METHODS AND MATERIALS

Twenty-nine patients with localized prostate cancer were accrued. Eligibility criteria included histologically confirmed adenocarcinoma, Karnofsky performance status >or=70, and no pelvic lymphadenopathy or distant metastases. The total dose to the prostate was 70.2 Gy in 20 patients and 73.8 Gy in 9 patients. Therapy was delivered using a 4-field technique with three-dimensional conformal planning. Amifostine was administered intrarectally as an aqueous solution 30 min before irradiation on the first 15 days of therapy. Amifostine was escalated in cohorts from 500 to 2500 mg. Proctoscopy was performed before therapy and at 9 months after completion. Most patients underwent repeat proctoscopy at 18 months. On Days 1 and 10 of radiotherapy, serum samples were collected for pharmacokinetic studies. The clinical symptoms (Radiation Therapy Oncology Group scale) and a proctoscopy score were assessed during follow-up.

RESULTS

All patients completed therapy with no amifostine-related toxicity at any dose level. The application was feasible and well tolerated. No substantial systemic absorption occurred. With a median follow-up of 26 months, 9 patients (33%) developed rectal bleeding (8 Grade 1, 1 Grade 2). At 9 months, 16 and 3 patients developed Grade 1 and Grade 2 telangiectasia, respectively. This was mostly confined to the anterior rectal wall. No visible mucosal edema, ulcerations, or strictures were noted. No significant differences were found between the proctoscopy findings at 9 and 18 months. Four patients (14%) developed symptoms suggestive of radiation damage that, on sigmoidoscopy, proved to be secondary to unrelated processes. These included preexisting nonspecific proctitis (n = 1), diverticular disease of the sigmoid colon (n = 1), rectal polyp (n = 1), and ulcerative colitis (n = 1). Symptoms developed significantly more often in patients receiving 500-1000 mg than in patients receiving 1500-2500 mg amifostine (7 [50%] of 14 vs. 2 [15%] of 13, p = 0.0325, one-sided chi-square test).

CONCLUSION

Intrarectal application of amifostine is feasible and well tolerated. Systemic absorption of amifostine and its metabolites is negligible, and close monitoring of patients is not required with rectal administration. Proctoscopy is superior to symptom score as a method of assessing radiation damage of the rectal wall. The preliminary efficacy data are encouraging, and further clinical studies are warranted.

Dose–volume relationship for acute side effects during high dose conformal radiotherapy for prostate cancer

PURPOSE

To determine acute and late complications for bladder and rectum and to determine dose-volume correlations.

METHODS AND MATERIALS

Sixty-four patients received definitive treatment for prostate cancer between January 1995 and December 1998 using conformal three-dimensional radiotherapy. Doses ranged from 72 to 80Gy. The acute and late side effects were gathered retrospectively, and graded according to Radiotherapy and Oncology Group criteria (RTOG). The patients were divided into two groups: <or=72Gy (Group A) and >or=76Gy (Group B) and had a mean follow-up of 32 and 22 months, respectively.

RESULTS

No grades 3-4 acute, urinary or rectal toxicity was reported. Acute grade 2 rectal complications were seen in 10 and 18% of the patients in Groups A and B, respectively. They were observed at a mean dose of 38Gy. Acute grade 2 urinary symptoms were 33 and 47% for Groups A and B, respectively. They were seen at a mean dose of 43Gy. Acute rectal symptoms were dose-volume related. Patients without diarrhea had a mean rectal volume receiving a dose of 70Gy or more of 8.5 cm(3). However, patients with RTOG 2 diarrhea had a volume of 16.5 cm(3) (P=0.042). No dose-volume relationship for acute bladder symptoms or late complications were seen. Grades 1-2 late rectal and bladder complications were seen in 11 and 8% of the patients, respectively. None required hospital admission or transfusion.

CONCLUSION

Radiotherapy to the prostate can be given at 80Gy. No grades 3-4 acute, urinary or rectal toxicity was reported. Acute rectal symptoms are dose-volume related.

Gastrointestinal toxicity of transperineal interstitial prostate brachytherapy

PURPOSE

To characterize the severity and time course of rectal toxicity following transperineal prostate brachytherapy using prospectively recorded data, and to determine factors associated with toxicity.

METHODS AND MATERIALS

One hundred thirty-four patients with prostate cancer treated with transperineal brachytherapy from 1997 to 1999 had rectal toxicity data available for analysis. Patients with Gleason score (GS) > 6, prostate-specific antigen (PSA) > 6, or stage > T2a were treated initially with external beam radiation therapy followed by brachytherapy boost; patients with none of these features were treated with brachytherapy alone. Both iodine-125 and palladium-103 sources were used, and loaded according to a modified Quimby distribution. At each follow-up, toxicity was recorded according to a modified RTOG gastrointestinal scale.

RESULTS

Thirty-nine percent of patients experienced gastrointestinal toxicity, mostly Grade 1. Median duration of symptoms was 6 months. Two patients experienced Grade 3 toxicity, both of whom had minimal symptoms until their 12-month follow-up. There was no Grade 4 or 5 toxicity. The addition of external beam radiation therapy (p = 0.003), higher clinical stage (p = 0.006), and Caucasian race (p = 0.01) were associated with increased incidence of toxicity.

CONCLUSION

Most patients with rectal toxicity have very mild symptoms. There is a small risk of severe late toxicity. External beam radiation, higher stage, and race are associated with toxicity.

[Conformal radiotherapy in prostate cancer: for whom and how?]

External radiotherapy is one of the modalities used to cure localized prostate carcinoma. Most of localized prostate carcinomas, specially those of the intermediate prognostic group, may benefit from escalated dose above 70 Gy at least as regard biochemical and clinical relapse free survival. 3D-CRT allows a reduction of the dose received by organs at risk and an increase of prostate dose over 70 Gy. It is on the way to become a standard. Intensity modulated radiation therapy increases dose homogeneity and reduces rectal dose. These methods necessitate rigorous procedures in reproducibility, delineation of volumes, dosimetry, daily treatment. They need also technological and human means. It is clear that localized prostate cancer is a good example for evaluation of these new radiotherapy modalities.

Potential improvements in the therapeutic ratio of prostate cancer irradiation: dose escalation of pathologically identified tumour nodules using intensity modulated radiotherapy

The potential of intensity modulated radiotherapy (IMRT) to improve the therapeutic ratio in prostate cancer by dose escalation of intraprostatic tumour nodules (IPTNs) was investigated using a simultaneous integrated boost technique. The prostate and organs-at-risk were outlined on CT images from six prostate cancer patients. Positions of IPTNs were transferred onto the CT images from prostate maps derived from sequential large block sections of whole prostatectomy specimens. Inverse planned IMRT dose distributions were created to irradiate the prostate to 70 Gy and all the IPTNs to 90 Gy. A second plan was produced to escalate only the dominant IPTN (DIPTN) to 90 Gy, mimicking current imaging techniques. These plans were compared with homogeneous prostate irradiation to 70 Gy using dose-volume histograms, tumour control probability (TCP) and normal tissue complication probability (NTCP) for the rectum. The mean dose to IPTNs was increased from 69.8 Gy to 89.1 Gy if all the IPTNs were dose escalated (p=0.0003). This corresponded to a mean increase in TCP of 8.7-31.2% depending on the alpha/beta ratio of prostate cancer (p<0.001), and a mean increase in rectal NTCP of 3.0% (p<0.001). If only the DIPTN was dose escalated, the TCP was increased by 6.4-27.5% (p<0.003) and the rectal NTCP was increased by 1.8% (p<0.01). In the dose escalated DIPTN IMRT plans, the highest rectal NTCP was seen in patients with IPTNs in the posterior peripheral zone close to the anterior rectal wall, and the lowest NTCP was seen with IPTNs in the lateral peripheral zone. The ratio of increased TCP to NTCP may represent an improvement in the therapeutic ratio, but was dependent on the position of the IPTN relative to the anterior rectal wall. Improvements in prostate imaging and prostate immobilization are required before clinical implementation would be possible. Clinical trials are required to confirm the clinical benefits of these improved dose distributions.

The influence of a rectal balloon tube as internal immobilization device on variations of volumes and dose-volume histograms during treatment course of conformal radiotherapy for prostate cancer

PURPOSE

A prospective comparative study of a subset of 10 consecutive patients was performed, to describe the effects of an air-inflated rectal balloon tube that has been used for prostate immobilization in 360 patients since 1994. In particular, influences on prostate motion, rectum filling variations, and dose-volume histograms (DVHs) of the rectum during a course of conformal radiotherapy were investigated.

METHODS AND MATERIALS

Computed tomographic (CT) examinations without and with rectal balloon (filled with 40 mL air) were performed at the start (t(0)), middle (t(mi)), and end of treatment (t(e)), resulting in 6 CT scans for each patient. Prostate displacement was measured from a lateral beam's-eye-view. DVHs of rectum as a solid organ, and anterior, posterior, and whole rectum wall were calculated at t(0), t(mi), and t(e), and variations during treatment were analyzed for both examinations, with and without balloon.

RESULTS

By use of the balloon, rectum filling variations (p = 0.04) and maximum anterior-posterior displacements of the prostate (p = 0.008) were reduced significantly, leading to a reduction in DVH variations during treatment. Maximum displacements of posterior prostate border (>5 mm) were found in 8/10 patients without a rectum balloon and in only 2/10 patients with the balloon. The balloon led to a significant reduction in partial posterior rectal wall volumes included in the high-dose regions, without significant changes at the anterior rectum wall in cases of irradiation of the prostate only. However, when entirely irradiating the whole seminal vesicles, this advantage was lost.

CONCLUSIONS

The rectal balloon catheter represents a simple technique to immobilize the prostate and to determine the position of the anterior rectal wall at daily treatment. This allows a reduction of margins, because of reduced prostate movement during treatment course.

Locally advanced prostate cancer

Standard therapy for clinically localized prostate cancer includes radical prostatectomy, external beam radiotherapy, or transperineal interstitial brachytherapy. Patients eligible for standard therapy are those with low risk features as defined by various risk group classifications, which generally include clinical stage T1 or T2a, serum prostate-specific antigen (PSA) less than 10 ng/mL, and biopsy Gleason sum of 6 or less. Although there has been important evolution in the performance of these techniques, particularly with respect to functional outcomes, these approaches for low-risk disease are relatively mature, and the cure rates with each of these therapies are similar in this patient population; locally advanced disease is more difficult to cure, however. Biochemical disease-free survival rates in men undergoing radical prostatectomy are clearly related to the pathologic stage. Prognostic groups can be defined based on pathologic stage with increasingly worse outcomes based on extracapsular extension (ECE), margin status, and the status of the lymph nodes and seminal vesicles. In patients with low risk features, the positive margin rate is generally low, making the presence or absence of ECE the dominant variable in predicting the likelihood of treatment failure. These observations suggest that more aggressive therapy is needed to cure those who are likely to have ECE or other adverse histologic features. Several nomograms predicting the likelihood of ECE or 5-year biochemical failure rates are now in routine clinical use, and can be used to select men at high risk of failure with single modality therapy for more aggressive treatment strategies. However, the optimal form of aggressive therapy for these patients is unknown.

Is diagnostic review of radiotherapy-planning CT scans important in the conformal therapy era?

OBJECTIVE

Detailed CT scans are often acquired during the radiotherapy planning process. This study was performed to determine the incidence of important benign and cancer-related CT findings on these scans.

SUBJECTS AND METHODS

From December 1998 to December 2000, 162 radiotherapy patients who were to be treated curatively underwent treatment planning CT scans on a helical scanner in the radiology department at Washington Hospital, Fremont, CA. All CT scans were prospectively interpreted relative to diagnoses, and reports were dictated for the medical records. The diagnostic reports and records on all patients were reviewed to determine the incidence of previously unknown benign or cancer-related findings, the impacts of such findings on treatment, and the need for additional radiologic studies or procedures on the basis of the CT interpretations.

RESULTS

Incidental benign findings were noted for 32 patients (20%). Potentially important benign findings were noted for three patients: two with aneurysms and one with a possible deep vein thrombosis. Potentially cancer-related findings were reported in 20 patients: a single liver lesion (four patients), multiple liver lesions (two patients), possible or probable lymphadenopathy (11 patients), abnormal soft tissue (one patient), a small-bowel obstruction (one patient), and a breast mass (one patient). After reviewing prior diagnostic studies and obtaining additional recommended studies, the physicians found that only three of the previously unknown findings required further investigation: two aneurysms, which did not require near-term treatment, and one metastatic neck node.

CONCLUSION

Routine diagnostic interpretation of radiotherapy planning scans resulted in few important medical findings and changed patient care for less than 1% of the patients.

Forward or inversely planned segmental multileaf collimator IMRT and sequential tomotherapy to treat multiple dominant intraprostatic lesions of prostate cancer to 90 Gy

PURPOSE

To investigate the technical feasibility of using forward or inversely planned segmental multileaf collimator (SMLC) intensity-modulated radiotherapy and sequential tomotherapy (ST) to escalate to a dose of 90 Gy to multiple dominant intraprostatic lesions within the prostate gland while delivering a dose of 75.6 Gy to the remaining prostate.

METHODS AND MATERIALS

A selected case with one dominant intraprostatic lesion located at the left base and a second dominant intraprostatic lesion at the right apex of the prostate was planned using three different intensity modulation techniques. Two plans were generated with inverse treatment planning, using either SMLC or ST with a special multivane collimator. The third plan also employed SMLC but was generated using forward planning. All three plans were compared based on dose-volume histograms, isodose distributions, and doses to sensitive normal structures.

RESULTS

All three plans meet and exceed the desired dose constraints, limiting doses to the rectum and bladder to an estimated RTOG Grade 2 complication rate of <10%. The ST plan achieved the best dose conformality, whereas the inverse SMLC plan gave the lowest dose to the rectal wall, and the forward SMLC plan obtained the best dose homogeneity inside the targets.

CONCLUSIONS

Using any of the three intensity-modulated techniques, it is technically feasible to concurrently treat multiple selected high-risk regions within the prostate to 90 Gy and the remaining prostate to 75.6 Gy, while keeping the doses to the rectum and the bladder significantly lower than those associated with a Grade 2 complication rate of 10%.

Treatment planning aids in prostate cancer: friend or foe?

BACKGROUND

Rectal barium is commonly used as a treatment planning aid for prostate cancer to delineate the anterior rectal wall. Previous research at the Ottawa Regional Cancer Centre demonstrated that retrograde urethrography results in a systematic shift of the prostate. We postulated that rectal barium could also cause prostate motion.

PURPOSE

The study was designed to evaluate the effects of rectal barium on prostate position.

METHODS AND MATERIALS

Thirty patients with cT1-T3 prostate cancer were evaluated. Three fiducial markers were placed in the prostate. During simulation, baseline posterior-anterior and lateral films were taken. Repeat films were taken after rectal barium opacification. The prostate position (identified by the fiducials) relative to bony landmarks was compared before and after rectal barium. Films were analyzed using PIPsPro software.

RESULTS

The rectal barium procedure resulted in a significant displacement of the prostate in the anterior and superior direction. The mean displacement of the prostate measured on the lateral films was 3.8 mm (SD: 4.4 mm) in the superior direction and 3.0 mm (SD: 3.1) in the anterior direction.

CONCLUSIONS

Rectal barium opacification results in a systematic shift of the prostate. This error could result in a geographic miss of the target; therefore, alternate methods of normal tissue definition should be used.