Advanced prostate cancer: the results of a randomized comparative trial of high dose irradiation boosting with conformal protons compared with conventional dose irradiation using photons alone

Review of clinical experience with ion beam radiotherapy

The article describes both the early development of oncology as a core discipline at the University of Heidelberg Hospital and the first steps towards ion beam treatment, from the pilot project carried out in co-operation with the Gesellschaft für Schwerionenforschung Darmstadt to the initial start-up of clinical service at the Heidelberg Heavy Ion Centre (HIT). We present an overview, based on data published in the literature, of the available clinical evidence relating the use of ion beam therapy to treat major indications in active particle centres. A rationale for the use of particle therapy in each of these indications is given. In view of the limited availability of data, we discuss the necessity to conduct clinical trials. We also look forward towards the next activities to be undertaken at the HIT.

Toxicity analysis of dose escalation from 75.6 gy to 81.0 gy in prostate cancer

OBJECTIVE

Several randomized trials have demonstrated a biochemical control advantage to an increase from the "conventional" 66 to 70 Gy range to the "high-dose" 75 to 81 Gy range; these trials have also, however, demonstrated a toxicity disadvantage. Our objective was to perform a toxicity analysis of a minor dose escalation (from 75.6 to 81.0 Gy) within this "high-dose" range.

METHODS

A total of 189 patients comprised the study population-119 received 75.6 Gy and 70 received 81.0 Gy. Acute, late, and final (at most recent follow-up) gastrointestinal (GI) and genitourinary (GU) toxicity were charted for each group and compared using the χ test. Ordered logit regression analyses were performed on each toxicity end point, using all major demographic, disease, and treatment factors as covariates.

RESULTS

The 81.0 Gy group had higher rates of grade 2 acute GU (P < 0.001), late GU (P = 0.001), and late GI (P = 0.082) toxicity, a lower rate of acute GI toxicity (P = 0.002) and no notable differences in final GU (P = 0.551) or final GI (P = 0.194) toxicity compared with the 75.6 Gy group. The ordered logit regression analyses showed that only age (P = 0.019) and radiotherapy dose (P = 0.016) correlated with acute GU toxicity and only radiotherapy dose (P = 0.018) correlated with late GU toxicity. Only intensity modulated radiotherapy use (P = 0.001) correlated with acute GI toxicity; no factors correlated with late GI toxicity or final GU or GI toxicity.

CONCLUSIONS

Although some increases in acute and late toxicity rates were observed with even a minor dose escalation from 75.6 to 81.0 Gy, notably no increases in final late GI or GU toxicity rates were observed.

Proton-beam therapy for prostate cancer

The treatment options for prostate cancer include prostatectomy, external-beam irradiation, brachytherapy, cryosurgery, focused ultrasound, hormonal therapy, watchful waiting, and various combinations of these modalities. Because the prostate abuts the bladder and rectum, the dose distributions of external-beam irradiations and the accuracy of their placement play crucial roles in the probability of tumor cure and the incidence of posttreatment complications. Principal among the newer radiation technologies is proton-beam therapy (PBT), whose dose distributions make it possible to deliver higher tumor doses and smaller doses to surrounding normal tissues than from x-ray systems. However, as the 10-year cause-specific survival for early-stage disease treated by radiation therapy now exceeds 90%, and with severe late toxicities in the range of 2% to 3%, randomized clinical trials provide the only means to demonstrate improved outcomes from PBT. Short of the data provided by such trials, the efficacy of PBT can be gleaned only from reports in the clinical literature, and, to date, these reports are equivocal. In view of the current health care crisis and the higher costs of PBT for prostate cancer, it is reasonable to assess the viability of this in-vogue but not-so-new technology.

International Conference on Advances in Radiation Oncology (ICARO): outcomes of an IAEA meeting

The IAEA held the International Conference on Advances in Radiation Oncology (ICARO) in Vienna on 27-29 April 2009. The Conference dealt with the issues and requirements posed by the transition from conventional radiotherapy to advanced modern technologies, including staffing, training, treatment planning and delivery, quality assurance (QA) and the optimal use of available resources. The current role of advanced technologies (defined as 3-dimensional and/or image guided treatment with photons or particles) in current clinical practice and future scenarios were discussed.

ICARO was organized by the IAEA at the request of the Member States and co-sponsored and supported by other international organizations to assess advances in technologies in radiation oncology in the face of economic challenges that most countries confront. Participants submitted research contributions, which were reviewed by a scientific committee and presented via 46 lectures and 103 posters. There were 327 participants from 70 Member States as well as participants from industry and government. The ICARO meeting provided an independent forum for the interaction of participants from developed and developing countries on current and developing issues related to radiation oncology.

Dose escalation improves cancer-related events at 10 years for intermediate- and high-risk prostate cancer patients treated with hypofractionated high-dose-rate boost and external beam radiotherapy

PURPOSE

To evaluate the 10-year outcomes of intermediate- and high-risk prostate cancer patients treated with a prospective dose escalation hypofractionated trial of pelvic external beam radiation therapy (P-EBRT) with a high-dose-rate (HDR) brachytherapy boost.

METHODS AND MATERIALS

From 1992 to 2007, 472 patients were treated with a HDR boost at William Beaumont Hospital. They had at least one of the following: a prostate-specific antigen (PSA) level of >10 ng/ml, a Gleason score of ≥7, or clinical stage ≥T2b. Patients received 46-Gy P-EBRT and an HDR boost. The HDR dose fractionation was divided into two dose levels. The prostate biologically equivalent dose (BED) low-dose-level group received <268 Gy, and the high-dose group received >268 Gy . Phoenix biochemical failure (BF) definition was used.

RESULTS

Median follow-up was 8.2 years (range, 0.4-17 years). The 10-year biochemical failure rate of 43.1% vs. 18.9%, (p < 0.001), the clinical failure rate of 23.4% vs. 7.7%, (p < 0.001), and the distant metastasis of 12.4% vs. 5.7%, (p = 0.028) were all significantly better for the high-dose level group. On Cox multivariate analysis, higher BED levels (p = 0.017; hazard ratio [HR] = 0.586), pretreatment PSA assays (p < 0.001, HR = 1.022), and Gleason scores (p = 0.004) were significant variables for reduced biochemical failure. Higher dose levels (p, 0.002; HR, 0.397) and Gleason scores (p < 0.001) were significant for clinical failure. Grade 3 genitourinary complications were 2% and 3%, respectively, and grade 3 gastrointestinal complication was <0.5%.

CONCLUSIONS

This prospective trial using P-EBRT with HDR boost and hypofractionated dose escalation demonstrates a strong dose-response relationship for intermediate- and high-risk prostate cancer patients. The improvement at 10 years for locoregional control with higher radiation doses (BED, > 268 Gy) has significantly decreased biochemical and clinical failures as well as distant metastasis.

Basics of particle therapy II biologic and dosimetric aspects of clinical hadron therapy

Besides photons and electrons, high-energy particles like protons, neutrons, ⁴He ions or heavier ions (C, Ne, etc) have been finding increasing applications in the treatment of radioresistant tumors and tumors located near critical structures. The main difference between photons and hadrons is their different biologic effect and depth-dose distribution. Generally speaking, protons are superior in dosimetric aspects whereas neutrons have advantages in biologic effectiveness because of the high linear energy transfer. In 1946 Robert Wilson first published the physical advantages in dose distribution of ion particles for cancer therapy. Since that time hadronic radiotherapy has been intensively studied in physics laboratories worldwide and clinical application have gradually come to fruition. Hadron therapy was made possible by the advances in accelerator technology, which increases the particles' energy high enough to place them at any depth within the patient's body. As a follow-up to the previous article Introduction to Hadrons, this review discusses certain biologic and dosimetric aspects of using protons, neutrons, and heavy charged particles for radiation therapy.

Acute and late toxicity after dose escalation to 82 GyE using conformal proton radiation for localized prostate cancer: initial report of American College of Radiology Phase II study 03-12

PURPOSE

Several randomized trials have shown a benefit of dose escalation to 78 to 79 Gy for men treated with external radiation for localized prostate cancer. Single-institution data suggest a benefit with even higher doses. American College of Radiology 03-12 is a Phase II trial testing the safety and efficacy of 82 GyE (Gray equivalent) delivered with conformal proton radiation.

METHODS AND MATERIALS

From 2003-2006, 85 men with localized prostate cancer were accrued to American College of Radiology 03-12. Eighty-four were eligible for analysis. They were treated with conformal proton radiation alone to a total dose of 82 GyE. The study was designed to test whether the rate of 18-month Grade 3+ late toxicity was greater than 10%.

RESULTS

The median follow-up was 31.6 months. Regarding treatment-related acute toxicity, there were 39 Grade 1 cases (46%), 19 Grade 2 cases (23%) and 2 Grade 3 cases (2%). Regarding genitourinary/gastrointestinal toxicity, there were 42 Grade 1 cases (50%), 12 Grade 2 cases (14%) and 1 Grade 3 case (1%). Regarding late toxicity, there were 28 Grade 1 cases (33%), 22 Grade 2 cases (26%), 6 Grade 3 cases (7%), and 1 Grade 4 case (1%). The late genitourinary/gastrointestinal rates were the same. The estimated rate of Grade 3+ late toxicity at 18 months was 6.08%.

CONCLUSIONS

Although not free of late toxicity, 82 GyE at 2 GyE per fraction delivered with conformal proton radiation did not exceed the late morbidity target tested in this trial. There was sufficient morbidity, however, that this may be the maximal dose that can be delivered safely with this technique and fractionation.

Current clinical evidence for proton therapy

Proton beam therapy provides the opportunity for more localized delivery of ionizing radiation with the potential for improved normal tissue avoidance to reduce treatment related morbidity and to allow for dose escalation to improve disease control and survival without increased toxicity. However, a systematic review of published peer-reviewed literature reported previously and updated here is devoid of any clinical data demonstrating benefit in terms of survival, tumor control, or toxicity in comparison with best conventional treatment for any of the tumors so far treated including skull base and ocular tumors, prostate cancer and childhood malignancies. The current lack of evidence for benefit of protons should provide a stimulus for continued research. Well designed in silico clinical trials using validated normal tissue complication probability-models are important to predict the magnitude of benefit for individual tumor sites but the future use of protons should be guided by clear evidence of benefit demonstrated in well-designed prospective studies, away from commercial influence, and this is likely to require international collaboration. Any complex and expensive technology, including proton therapy, should not be employed on the basis of belief alone and requires testing to avoid inappropriate use of potential detriment to future patients.

A method to separate the rectum from the prostate during proton beam radiotherapy of prostate cancer patients

The use of protons for curative treatment of prostate cancer is increasing, either as a single treatment modality or in combination with conventional radiotherapy. The proximity between prostate (target) and rectum (organ at risk) often leads to a compromise between dose to target and organ at risk.

MATERIAL AND METHODS

The present study describes a method where the distance between prostate and rectum is increased by retraction of the rectum in dorsal direction. Comparative treatment plans with and without retraction of the rectum in the same patients have been studied. Nine patients with biopsy proven, localised adenocarcinoma of the prostate were studied. A cylindrical rod of Perspex was inserted into the rectum. This device allows the rectum to be retracted posteriorly. The patients were given a proton boost of 20 Gy in four fractions of 5 Gy in addition to a conventional photon beam treatment to a dose of 50 Gy in 25 fractions of 2 Gy.

RESULTS

Comparative treatment planning shows that the treatment plan with rectal retraction significantly reduces (p<0.01) the volume of the rectal wall receiving high doses (equal to 70 Gy in 2 Gy fractions) in all patients.

CONCLUSIONS

The proton boost treatment with retraction of rectum during treatment decreases the rectal dose substantially. This is expected to reduce rectal side effects.

[Is proton beam therapy the future of radiotherapy? Part I: clinical aspects]

Proton beam therapy uses positively charged particles, protons, whose physical properties improve dose-distribution (Bragg peak characterized by a sharp distal and lateral penumbra) compared with conventional photon-based radiation therapy (X-ray). These ballistic advantages apply to the treatment of deep-sited tumours located close to critical structures and requiring high-dose levels. [60-250 MeV] proton-beam therapy is now widely accepted as the "gold standard" in specific indications in adults--ocular melanoma, chordoma and chondrosarcoma of the base of skull --and is regarded as a highly promising treatment modality in the treatment of paediatric malignancies (brain tumours, sarcomas…). This includes the relative sparing of surrounding normal organs from low and mid-doses that can cause deleterious side-effects such as radiation-induced secondary malignancies. Other clinical studies are currently testing proton beam in dose-escalation evaluations, in prostate, lung, hepatocellular cancers, etc. Clinical validation of these new indications appears necessary. To date, over 60,000 patients worldwide have received part or all of their radiation therapy program by proton beams, in approximately 30 treatment facilities.

Randomized trial comparing conventional-dose with high-dose conformal radiation therapy in early-stage adenocarcinoma of the prostate: long-term results from proton radiation oncology group/american college of radiology 95-09

PURPOSE To test the hypothesis that increasing radiation dose delivered to men with early-stage prostate cancer improves clinical outcomes. PATIENTS AND METHODS Men with T1b-T2b prostate cancer and prostate-specific antigen </= 15 ng/mL were randomly assigned to a total dose of either 70.2 Gray equivalents (GyE; conventional) or 79.2 GyE (high). No patient received androgen suppression therapy with radiation. Local failure (LF), biochemical failure (BF), and overall survival (OS) were outcomes. Results A total of 393 men were randomly assigned, and median follow-up was 8.9 years. Men receiving high-dose radiation therapy were significantly less likely to have LF, with a hazard ratio of 0.57. The 10-year American Society for Therapeutic Radiology and Oncology BF rates were 32.4% for conventional-dose and 16.7% for high-dose radiation therapy (P < .0001). This difference held when only those with low-risk disease (n = 227; 58% of total) were examined: 28.2% for conventional and 7.1% for high dose (P < .0001). There was a strong trend in the same direction for the intermediate-risk patients (n = 144; 37% of total; 42.1% v 30.4%, P = .06). Eleven percent of patients subsequently required androgen deprivation for recurrence after conventional dose compared with 6% after high dose (P = .047). There remains no difference in OS rates between the treatment arms (78.4% v 83.4%; P = .41). Two percent of patients in both arms experienced late grade >/= 3 genitourinary toxicity, and 1% of patients in the high-dose arm experienced late grade >/= 3 GI toxicity. CONCLUSION This randomized controlled trial shows superior long-term cancer control for men with localized prostate cancer receiving high-dose versus conventional-dose radiation. This was achieved without an increase in grade >/= 3 late urinary or rectal morbidity.

Moderate dose escalation in three-dimensional conformal localized prostate cancer radiotherapy: single-institutional experience in 398 patients comparing 66 Gy versus 70 Gy versus 74 Gy

PURPOSE

To evaluate the clinical outcome in prostate cancer patients treated at one single institution by the implementation of moderate dose escalation.

PATIENTS AND METHODS

A total of 398 patients with histologically verified localized prostate cancer (T1-3 Nx0 Mx0) were treated by three-dimensional conformal radiotherapy with/without additional hormonal therapy. Risk group distribution was as follows: 106 low-risk (27%), 164 intermediate-risk (41%), and 128 high-risk (32%) patients. Total local dose was increased from 66 Gy (1994-1998) to 70 Gy (1998-2003) and 74 Gy (1998-2005). Biochemical no evidence of disease (bNED: ASTRO/Phoenix definition) and late gastrointestinal/urogenital side effects (EORTC/RTOG) were assessed.

RESULTS

Median follow-up was 64 months. The 5-year bNED rates according to 66 Gy, 70 Gy and 74 Gy were 37%, 64% and 63% (ASTRO), and 54%, 74% and 69% (Phoenix), respectively. In multivariate analysis, age and T-stage were significant in predicting bNED. The 5-year bNED rates (ASTRO) according to 66 Gy, 70 Gy and 74 Gy were 40%, 78% and 73% in the low-risk group, 41%, 55% and 85% in the intermediate-risk group, and 30%, 53% and 52% in the high-risk group. Intermediate-risk patients showed a significant improvement of bNED by increasing the dose up to 74 Gy. The 5-year actuarial rates of gastrointestinal/urogenital side effects grade > or = 2 were 18%/16% (66 Gy), 20%/24% (70 Gy), and 27%/28% (74 Gy).

CONCLUSION

A benefit of local doses at a level of > or = 70 Gy could be detected showing the highest increase of prostate-specific antigen control in the intermediate-risk group. The amount of patients reporting of severe late side effects is small.

Higher-than-conventional radiation doses in localized prostate cancer treatment: a meta-analysis of randomized, controlled trials

PURPOSE

To determine in a meta-analysis whether the outcomes in men with localized prostate cancer treated with high-dose radiotherapy (HDRT) are better than those in men treated with conventional-dose radiotherapy (CDRT), by quantifying the effect of the total dose of radiotherapy on biochemical control (BC).

METHODS AND MATERIALS

The MEDLINE, EMBASE, CANCERLIT, and Cochrane Library databases, as well as the proceedings of annual meetings, were systematically searched to identify randomized, controlled studies comparing HDRT with CDRT for localized prostate cancer. To evaluate the dose-response relationship, we conducted a meta-regression analysis of BC ratios by means of weighted linear regression.

RESULTS

Seven RCTs with a total patient population of 2812 were identified that met the study criteria. Pooled results from these RCTs showed a significant reduction in the incidence of biochemical failure in those patients with prostate cancer treated with HDRT (p < 0.0001). However, there was no difference in the mortality rate (p = 0.38) and specific prostate cancer mortality rates (p = 0.45) between the groups receiving HDRT and CDRT. However, there were more cases of late Grade >2 gastrointestinal toxicity after HDRT than after CDRT. In the subgroup analysis, patients classified as being at low (p = 0.007), intermediate (p < 0.0001), and high risk (p < 0.0001) of biochemical failure all showed a benefit from HDRT. The meta-regression analysis also detected a linear correlation between the total dose of radiotherapy and biochemical failure (BC = -67.3 + [1.8 x radiotherapy total dose in Gy]; p = 0.04).

CONCLUSIONS

Our meta-analysis showed that HDRT is superior to CDRT in preventing biochemical failure in low-, intermediate-, and high-risk prostate cancer patients, suggesting that this should be offered as a treatment for all patients, regardless of their risk status.

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

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

Radiation techniques in neuro-oncology

Radiation therapy plays a critical role in the management of tumors of the brain. A variety of radiotherapy techniques have been used to treat these tumors. This review describes both classic and more recent and advanced techniques available to manage these tumors. Included is a discussion of standard two- and three-dimensional radiation, as well as intensity-modulated radiotherapy, image-guided radiation therapy, stereotactic radiosurgery, and heavy particles.

Treatment of chordomas with CyberKnife: georgetown university experience and treatment recommendations

OBJECTIVE

To determine the efficacy and safety of chordoma treatment with CyberKnife (Accuray, Inc., Sunnyvale, CA) stereotactic radiosurgery (CK/SRS).

METHODS

Eighteen patients with chordoma were treated with CK/SRS as a primary adjuvant (17 patients) or the only treatment (1 patient). The series included 24 lesions (28 treatments). The median age of the patients was 60 years (range, 24-85 years). Forty-four percent of the tumors were located in the mobile spine, 39% inside the cranium, and 17% in the sacral region. The male-to-female ratio was 1:1. The mean tumor volume was 128.0 mL (range, 12.0-457.3 mL), and the median dose of 35 Gy (range, 24.0-40.0 Gy) was delivered in 5 sessions. The median follow-up period was 46 months (range, 7-65 months).

RESULTS

There were 3 significant complications in patients with previous irradiation, including infection in the surgical/radiation site (2 patients) and decreased vision (1 patient). Improvement in pain and quality of life did not reach statistical significance (alpha = 0.05). Seven patients experienced recurrence at a median of 10 months (range, 5-38 months), and 4 patients with disseminated disease died 7 to 48 months after therapy. Two patients had a partial response, whereas 9 others had stable disease. The local control rate at 65 months was 59.1%, with an overall survival of 74.3% and disease-specific survival of 88.9%. We estimated an alpha/beta ratio of 2.45 for chordomas, which supports hypofractionation.

CONCLUSION

The CK/SRS safety and efficacy profile compares favorably with those of other treatment delivery systems. CK/SRS appears to reduce tumor volume, given an adequate dose. The authors recommend treatment with 40 Gy in 5 sessions to the clinical treatment volume, which includes the gross tumor volume and at least a 1-cm margin.

Volumetric modulated Arc therapy and conventional intensity-modulated radiotherapy for simultaneous maximal intraprostatic boost: a planning comparison study

AIMS

Volumetric modulated arc therapy (VMAT) is a novel extension of intensity-modulated radiotherapy (IMRT) where an optimised three-dimensional dose distribution may be delivered in a single gantry rotation. This optimisation algorithm is the predecessor to Varian's RapidArc. The aim of this study was to compare the ability of conventional static nine-field IMRT (cIMRT) and VMAT to boost as much of the clinical target volume (CTV) as possible to 88.8Gy without exceeding organ at risk (OAR) dose-volume constraints.

MATERIALS AND METHODS

Optimal cIMRT and VMAT radiotherapy plans were produced for 10 patients with localised prostate cancer using common planning objectives: (1) Treat >or=98% of the planning target volume (PTV) to >or=95% of the prescription dose (74Gy in 37 fractions); (2) keep OAR doses within predefined limits; (3) treat as much of prostate CTV (minus urethra) as possible to >or=120% of prescription dose (=88.8Gy); (4) keep within maximum dose limits in and out of target volumes; (5) conformality index (volume of 95% isodose/volume of PTV)<or=1.2.

RESULTS

VMAT and cIMRT boosted an average of 68.8 and 63.5% of the CTV to >or=120% of the prescription dose (P=0.002). All dose constraints were kept within predefined limits. VMAT and cIMRT required an average of 949 and 1819 monitor units and 3.7 and 9.6min, respectively, to deliver a single radiation fraction.

CONCLUSIONS

VMAT is able to boost more of the CTV to >or=120% than cIMRT without contravening OAR dose constraints, and uses 48% fewer monitor units. Treatment times were 61% less than with cIMRT.

Moderate risk-adapted dose escalation with three-dimensional conformal radiotherapy of localized prostate cancer from 70 to 74 Gy. First report on 5-year morbidity and biochemical control from a prospective Austrian-German multicenter phase II trial

PURPOSE

Evaluation of late side effects and biochemical control (bNED) 5 years after three-dimensional radiotherapy with moderate, risk-adapted dose escalation.

PATIENTS AND METHODS

From 03/1999 to 07/2002, 486 patients have been registered in the prospective Austrian-German multicenter phase II trial (AUGE). 399 (82%) localized prostate cancer patients (T1-3 Nx/N0 M0) were evaluated. The low- and intermediate-risk groups were treated with 70 Gy, the high-risk group with 74 Gy, respectively. Additional hormonal therapy (HT) was recommended for intermediate- and high-risk group patients. Late toxicity (EORTC/RTOG) and bNED (ASTRO and Phoenix) were prospectively assessed.

RESULTS

Median follow-up was 65 months. Distribution concerning risk groups (low-, intermediate-, high-risk group) showed 29%, 50% and 21% of patients, respectively. HT was given in 87% of patients. The 5-year actuarial rates of late side effects grade > or = 2 for 70 Gy/74 Gy were 28%/30% (gastrointestinal; p = 0.73) and 19%/34% (urogenital; p = 0,06). The 5-year actuarial bNED rate stratified by risk groups (low-, intermediate-, high-risk group) was 74%, 66% and 50% (ASTRO), and 81%, 80% and 60% (Phoenix), respectively. Within multivariate analysis T-stage and initial prostate specific antigen were significant factors influencing bNED (ASTRO) whereas Gleason Score and duration of HT were not.

CONCLUSION

Dose escalation within standard three-dimensional conformal radiotherapy (3D-CRT) up to a level of 74 Gy did not result in significantly increased gastrointestinal side effects, whereas urogenital side effects showed an increase close to significance. However, the total number of patients with severe toxicity was low. To achieve high tumor control rates with acceptable treatment-related morbidity, local doses of at least 74 Gy should be considered, in particular for intermediate- or high-risk patients applying 3D-CRT.

Dosimetric changes resulting from patient rotational setup errors in proton therapy prostate plans

PURPOSE

To evaluate the dose changes to the target and critical structures from rotational setup errors in prostate cancer patients treated with proton therapy.

METHODS AND MATERIALS

A total of 70 plans were analyzed for 10 patients treated with parallel-opposed proton beams to a dose of 7,600 (60)Co-cGy-equivalent (CcGE) in 200 CcGE fractions to the clinical target volume (i.e., prostate and proximal seminal vesicles). Rotational setup errors of +3 degrees , -3 degrees , +5 degrees , and -5 degrees (to simulate pelvic tilt) were generated by adjusting the gantry. Horizontal couch shifts of +3 degrees and -3 degrees (to simulate longitudinal setup variability) were also generated. Verification plans were recomputed, keeping the same treatment parameters as the control.

RESULTS

All changes shown are for 38 fractions. The mean clinical target volume dose was 7,780 CcGE. The mean change in the clinical target volume dose in the worse case scenario for all shifts was 2 CcGE (absolute range in worst case scenario, 7,729-7,848 CcGE). The mean changes in the critical organ dose in the worst case scenario was 6 CcGE (bladder), 18 CcGE (rectum), 36 CcGE (anterior rectal wall), and 141 CcGE (femoral heads) for all plans. In general, the percentage of change in the worse case scenario for all shifts to the critical structures was <5%. Deviations in the absolute percentage of volume of organ receiving 45 and 70 Gy for the bladder and rectum were <2% for all plans.

CONCLUSION

Patient rotational movements of 3 degrees and 5 degrees and horizontal couch shifts of 3 degrees in prostate proton planning did not confer clinically significant dose changes to the target volumes or critical structures.

Acute and late toxicity in prostate cancer patients treated by dose escalated intensity modulated radiation therapy and organ tracking

Background

To report acute and late toxicity in prostate cancer patients treated by dose escalated intensity-modulated radiation therapy (IMRT) and organ tracking.

Methods

From 06/2004 to 12/2005 39 men were treated by 80 Gy IMRT along with organ tracking. Median age was 69 years, risk of recurrence was low 18%, intermediate 21% and high in 61% patients. Hormone therapy (HT) was received by 74% of patients. Toxicity was scored according to the CTC scale version 3.0. Median follow-up (FU) was 29 months.

Results

Acute and maximal late grade 2 gastrointestinal (GI) toxicity was 3% and 8%, late grade 2 GI toxicity dropped to 0% at the end of FU. No acute or late grade 3 GI toxicity was observed. Grade 2 and 3 pre-treatment genitourinary (GU) morbidity (PGUM) was 20% and 5%. Acute and maximal late grade 2 GU toxicity was 56% and 28% and late grade 2 GU toxicity decreased to 15% of patients at the end of FU. Acute and maximal late grade 3 GU toxicity was 8% and 3%, respectively. Decreased late ≥ grade 2 GU toxicity free survival was associated with higher age (P = .025), absence of HT (P = .016) and higher PGUM (P < .001).

Discussion

GI toxicity rates after IMRT and organ tracking are excellent, GU toxicity rates are strongly related to PGUM.

Update of Dutch multicenter dose-escalation trial of radiotherapy for localized prostate cancer

PURPOSE

To update the analysis of the Dutch dose-escalation trial of radiotherapy for prostate cancer.

PATIENTS AND METHODS

A total of 669 patients with localized prostate cancer were randomly assigned to receive 68 or 78 Gy. The patients were stratified by age, institution, use of neoadjuvant or adjuvant hormonal therapy, and treatment group. The primary endpoint was freedom from failure (FFF), with failure defined as clinical or biochemical failure. Two definitions of biochemical failure were used: the American Society for Therapeutic Radiology and Oncology definition (three consecutive increases in prostate-specific antigen level) and the Phoenix definition (nadir plus 2 microe secondary endpoints were freedom from clinical failure, overall survival, and genitourinary and gastrointestinal toxicity.

RESULTS

After a median follow-up of 70 months, the FFF using the American Society for Therapeutic Radiology and Oncology definition was significantly better in the 78-Gy arm than in the 68-Gy arm (7-year FFF rate, 54% vs. 47%, respectively; p = 0.04). The FFF using the Phoenix definition was also significantly better in the 78-Gy arm than in the 68-Gy arm (7-year FFF rate, 56% vs. 45%, respectively; p = 0.03). However, no differences in freedom from clinical failure or overall survival were observed. The incidence of late Grade 2 or greater genitourinary toxicity was similar in both arms (40% and 41% at 7 years; p = 0.6). However, the cumulative incidence of late Grade 2 or greater gastrointestinal toxicity was increased in the 78-Gy arm compared with the 68-Gy arm (35% vs. 25% at 7 years; p = 0.04).

CONCLUSION

The results of our study have shown a statistically significant improvement in FFF in prostate cancer patients treated with 78 Gy but with a greater rate of late gastrointestinal toxicity.

Advanced-technology radiation therapy for bone sarcomas

BACKGROUND

Bone sarcomas are rare primary tumors. Radiation therapy (RT) can be useful in securing local control in cases where negative surgical margins cannot be obtained or where tumors are not resected. Recent technical advances in RT offer the opportunity to deliver radiation to these tumors with higher precision, thus allowing higher doses to the tumor target with lower doses to critical normal tissues, which can improve local tumor control and/or reduce treatment-related morbidity.

METHODS

The authors conducted a survey of recent technical developments that have been applied to the RT for bone sarcomas.

RESULTS

RT techniques that show promise include intensity-modulated photon radiation therapy, 3-D conformal proton RT, intensity-modulated proton RT, heavy charged-particle RT, intraoperative RT, and brachytherapy. All of these techniques permit the delivery of higher radiation doses to the target and less dose to normal tissue than had been possible with conventional 3-D conformal radiation techniques. Protons deliver substantially less dose to normal tissues than photons.

CONCLUSIONS

Data from clinical studies using these advanced radiation techniques suggest that they can improve the therapeutic ratio (the ratio of local control efficacy to the risk of complications). This is expected to improve the treatment outcome for these challenging tumors.

Dose–Volume Comparison of Proton Therapy and Intensity-Modulated Radiotherapy for Prostate Cancer

PURPOSE

The contrast in dose distribution between proton radiotherapy (RT) and intensity-modulated RT (IMRT) is unclear, particularly in regard to critical structures such as the rectum and bladder.

METHODS AND MATERIALS

Between August and November 2006, the first 10 consecutive patients treated in our Phase II low-risk prostate proton protocol (University of Florida Proton Therapy Institute protocol 0001) were reviewed. The double-scatter proton beam plans used in treatment were analyzed for various dosimetric endpoints. For all plans, each beam dose distribution, angle, smearing, and aperture margin were optimized. IMRT plans were created for all patients and simultaneously analyzed. The IMRT plans were optimized through multiple volume objectives, beam weighting, and individual leaf movement. The patients were treated to 78 Gray-equivalents (GE) in 2-GE fractions with a biologically equivalent dose of 1.1.

RESULTS

All rectal and rectal wall volumes treated to 10-80 GE (percentage of volume receiving 10-80 GE [V(10)-V(80)]) were significantly lower with proton therapy (p < 0.05). The rectal V(50) was reduced from 31.3% +/- 4.1% with IMRT to 14.6% +/- 3.0% with proton therapy for a relative improvement of 53.4% and an absolute benefit of 16.7% (p < 0.001). The mean rectal dose decreased 59% with proton therapy (p < 0.001). For the bladder and bladder wall, proton therapy produced significantly smaller volumes treated to doses of 10-35 GE (p < 0.05) with a nonsignificant advantage demonstrated for the volume receiving < or =60 GE. The bladder V(30) was reduced with proton therapy for a relative improvement of 35.3% and an absolute benefit of 15.1% (p = 0.02). The mean bladder dose decreased 35% with proton therapy (p = 0.002).

CONCLUSION

Compared with IMRT, proton therapy reduced the dose to the dose-limiting normal structures while maintaining excellent planning target volume coverage.

Should positive phase III clinical trial data be required before proton beam therapy is more widely adopted? No

PURPOSE

Evaluate the rationale for the proposals that prior to a wider use of proton radiation therapy there must be supporting data from phase III clinical trials. That is, would less dose to normal tissues be an advantage to the patient?

METHODS

Assess the basis for the assertion that proton dose distributions are superior to those of photons for most situations. Consider the requirements for determining the risks of normal tissue injury, acute and remote, in the examination of the data from a trial. Analyze the probable cost differential between high technology photon and proton therapy. Evaluate the rationale for phase III clinical trials of proton vs photon radiation therapy when the only difference in dose delivered is a difference in distribution of low LET radiation.

RESULTS

The distributions of biological effective dose by protons are superior to those by X-rays for most clinical situations, viz. for a defined dose and dose distribution to the target by protons there is a lower dose to non-target tissues. This superiority is due to these physical properties of protons: (1) protons have a finite range and that range is exclusively dependent on the initial energy and the density distribution along the beam path; (2) the Bragg peak; (3) the proton energy distribution may be designed to provide a spread out Bragg peak that yields a uniform dose across the target volume and virtually zero dose deep to the target. Importantly, proton and photon treatment plans can employ beams in the same number and directions (coplanar, non-co-planar), utilize intensity modulation and employ 4D image guided techniques. Thus, the only difference between protons and photons is the distribution of biologically effective dose and this difference can be readily evaluated and quantified. Additionally, this dose distribution advantage should increase the tolerance of certain chemotherapeutic agents and thus permit higher drug doses. The cost of service (not developmental) proton therapy performed in 3-5 gantry centers operating 14-16 h/day and 6 days/week is likely to be equal to or less than twice that of high technology X-ray therapy.

CONCLUSIONS

Proton therapy provides superior distributions of low LET radiation dose relative to that by photon therapy for treatment of a large proportion of tumor/normal tissue situations. Our assessment is that there is no medical rationale for clinical trials of protons as they deliver lower biologically effective doses to non-target tissue than do photons for a specified dose and dose distribution to the target. Based on present knowledge, there will be some gain for patients treated by proton beam techniques. This is so even though quantitation of the clinical gain is less secure than the quantitation of reduction in physical dose. Were proton therapy less expensive than X-ray therapy, there would be no interest in conducting phase III trails. The talent, effort and funds required to conduct phase III clinical trials of protons vs photons would surely be more productive in the advancement of radiation oncology if employed to investigate real problems, e.g. the most effective total dose, dose fractionation, definition of CTV and GTV, means for reduction of PTV and the gains and risks of combined modality therapy.

Late rectal and urinary toxicity from conformal, dose-escalated radiation therapy for prostate cancer: a prospective study of 402 patients

This study investigates the rate of late rectal and urinary toxicity from three-dimensional conformal radiation therapy (3DCRT) for localized prostate cancer. The influence of neoadjuvant androgen deprivation (AD) on toxicity rates was also examined. A total of 402 men at Liverpool and Westmead hospitals received radical 3DCRT for localized prostate cancer between 1999 and 2003. Patients received either 70 Gy or 74 Gy, according to their prognostic risk grouping and or date of commencing radiation therapy (RT). Late rectal and urinary toxicity data were collected prospectively using Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer criteria. The median follow up of this cohort was 43.5 months. At 36 months, the cumulative incidence of >or=grade 2 rectal and urinary toxicities was 6.7 and 17.5%, respectively. Peak prevalence of late urinary toxicity occurred at 36 months (9.5%), although late rectal toxicity was highest at 12 months (2.9%) from completion of 3DCRT. The use of AD did not cause additional late toxicities. Patients receiving 74 Gy did not experience significantly worse toxicities than the group receiving 70 Gy.

Radiothérapie guidée par l'image

Recent advances in radiation oncology are based on improvement in dose distribution thanks to IMRT and improvement in target definition through new diagnostic imaging such as spectroscopic or functional MRI or PET. However, anatomic variations may occur during treatment decreasing the benefit of such optimization. Image-guided radiotherapy reduces geometric uncertainties occurring during treatment and therefore should reduce dose delivered to healthy tissues and enable dose escalation to enhance tumour control. However, IGRT experience is still limited, while a wide panel of IGRT modalities is available. A strong quality control is required for safety and proper evaluation of the clinical benefit of IGRT combined or not with IMRT.