Dose escalation with 3D-CRT in prostate cancer: French study of dose escalation with conformal 3D radiotherapy in prostate cancer-preliminary results

Comparison between Conventional IMRT Planning and a Novel Real-Time Adaptive Planning Strategy in Hypofractionated Regimes for Prostate Cancer: A Proof-of-Concept Planning Study

In prostate cancer external beam radiation therapy (EBRT), intra-fraction prostate drifts may compromise the treatment efficacy by underdosing the target and/or overdosing the organs at risk. In this study, a recently developed real-time adaptive planning strategy for intensity-modulated radiation therapy (IMRT) for prostate cancer was evaluated in hypofractionated regimes against traditional treatment planning based on a treatment volume margin expansion. The proposed workflow makes use of a “library of plans” corresponding to possible intra-fraction prostate positions. During delivery, at each beam end, the plan prepared for the position of the prostate closest to the current one is selected and the corresponding beam delivered. This adaptive planning strategy was compared with the traditional approach on a clinical prostate cancer case where different prostate shift magnitudes were considered. Five, six and fifteen fraction hypofractionated schemes were considered for each of these scenarios. When shifts larger than the treatment margin were present, using the traditional approach the seminal vesicles were underdosed by 3–4% of the prescribed dose. The adaptive approach instead allowed for correct target dose coverage and lowered the dose on the rectum for each dosimetric endpoint on average by 3–4% in all the fractionation schemes. Standard intensity-modulated radiation therapy planning did not always guarantee a correct dose distribution on the seminal vesicles and the rectum. The adaptive planning strategy proposed resulted insensitive to the intra-fraction prostate drifts, produced a dose distribution in agreement with the dosimetric requirements in every case analysed and significantly lowered the dose on the rectum.

Real-time adaptive planning method for radiotherapy treatment delivery for prostate cancer patients, based on a library of plans accounting for possible anatomy configuration changes

BACKGROUND AND PURPOSE

In prostate cancer treatment with external beam radiation therapy (EBRT), prostate motion and internal changes in tissue distribution can lead to a decrease in plan quality. In most currently used planning methods, the uncertainties due to prostate motion are compensated by irradiating a larger treatment volume. However, this could cause underdosage of the treatment volume and overdosage of the organs at risk (OARs). To reduce this problem, in this proof of principle study we developed and evaluated a novel adaptive planning method. The strategy proposed corrects the dose delivered by each beam according to the actual position of the target in order to produce a final dose distribution dosimetrically as similar as possible to the prescribed one.

MATERIAL AND METHODS

Our adaptive planning method was tested on a phantom case and on a clinical case. For the first, a pilot study was performed on an in-silico pelvic phantom. A "library" of intensity modulated RT (IMRT) plans corresponding to possible positions of the prostate during a treatment fraction was generated at planning stage. Then a 3D random walk model was used to simulate possible displacements of the prostate during the treatment fraction. At treatment stage, at the end of each beam, based on the current position of the target, the beam from the library of plans, which could reproduce the best approximation of the prescribed dose distribution, was selected and delivered. In the clinical case, the same approach was used on two prostate cancer patients: for the first a tissue deformation was simulated in-silico and for the second a cone beam CT (CBCT) taken during the treatment was used to simulate an intra-fraction change. Then, dosimetric comparisons with the standard treatment plan and, for the second patient, also with an isocenter shift correction, were performed.

RESULTS

For the phantom case, the plan generated using the adaptive planning method was able to meet all the dosimetric requirements and to correct for a misdosage of 13% of the dose prescription on the prostate. For the first clinical case, the standard planning method caused underdosage of the seminal vesicles, respectively by 5% and 4% of the prescribed dose, when the position changes for the target were correctly taken into account. The proposed adaptive planning method corrected any possible missed target coverage, reducing at the same time the dose on the OARs. For the second clinical case, both with the standard planning strategy and with the isocenter shift correction target coverage was significantly worsened (in particular uniformity) and some organs exceeded some toxicity objectives. While with our approach, the most uniform coverage for the target was produced and systematically the lowest toxicity values for the organs at risk were achieved.

CONCLUSIONS

In our proof of principle study, the adaptive planning method performed better than the standard planning and the isocenter shift methods for prostate EBRT. It improved the coverage of the treatment volumes and lowered the dose to the OARs. This planning method is particularly promising for hypofractionated IMRT treatments in which a higher precision and control on dose deposition are needed. Further studies will be performed to test more extensively the proposed adaptive planning method and to evaluate it at a full clinical level.

The benefit of using bladder sub-volume equivalent uniform dose constraints in prostate intensity-modulated radiotherapy planning

Background

To assess the benefits of bladder wall sub-volume equivalent uniform dose (EUD) constraints in prostate cancer intensity-modulated radiotherapy (IMRT) planning.

Methods

Two IMRT plans, with and without EUD constraints on the bladder wall, were generated using beams that deliver 80 Gy to the prostate and 46 Gy to the seminal vesicles and were compared in 53 prostate cancer patients. The bladder wall was defined as the volume between the external manually delineated wall and a contraction of 7 mm apart from it. The bladder wall was then separated into two parts: the internal-bladder wall (bla-in) represented by the portion of the bladder wall that intersected with the planning target volume (PTV) plus 5 mm extension; the external-bladder wall (bla-ex) represented by the remaining part of the bladder wall. In the IMRT plan with EUD constraints, the values of “a” parameter for the EUD models were 10.0 for bla-in and 2.3 for bla-ex. The plans with and without EUD constraints were compared in terms of dose–volume histograms, 5-year bladder and rectum normal tissue complication probability values, as well as tumor control probability (TCP) values.

Results

The use of bladder sub-volume EUD constraints decreased both the doses to the bladder wall (V₇₀: 22.76% vs 19.65%, D_mean: 39.82 Gy vs 35.45 Gy) and the 5-year bladder complication probabilities (≥LENT/SOMA Grade 2: 20.35% vs 17.96%; bladder bleeding: 10.63% vs 8.64%). The doses to the rectum wall and the rectum complication probabilities were also slightly decreased by the EUD constraints compared to physical constraints only. The minimal dose and the V_76Gy of PTV_prostate were, however, slightly decreased by EUD optimization, nevertheless without significant difference in TCP values between the two plans, and the PTV parameters finally respected the Groupe d’Etude des Tumeurs Uro-Génitales recommendations.

Conclusion

Separating the bladder wall into two parts with appropriate EUD optimization may reduce bladder toxicity in prostate IMRT. Combining biological constraints with physical constraints in the organs at risk at the inverse planning step of IMRT may improve the dose distribution.

Localized prostate cancer treated with external beam radiation therapy: Long-term outcomes at a European comprehensive cancer centre

AIMS AND BACKGROUND

To present survival and toxicity outcomes in patients with clinically localized, non-metastatic prostate cancer (PCa) treated with external beam radiotherapy (EBRT) combined with androgen deprivation therapy (ADT).

MATERIALS AND METHODS

Retrospective study of 849 PCa patients (pts) treated from 1996 to 2005. Until August 2000, all patients (281) were treated with conventional dose EBRT (<76 Gy); subsequent pts received ≥76 Gy (565 pts). Median age was 70 years (range, 39-82). Most pts were intermediate (353; 42.8%) or high-risk (344; 41.7%). Mean PSA was 10.1 ng/ml. Median dose to the prostate was 75 Gy. Complete ADT was administered to 525 pts (61.8%).

RESULTS

Median follow-up was 109.6 months (range, 68.3-193.4). Overall survival (OS) was 92.5% and 81.1% at 5 and 10 years; by risk group (low, intermediate, high), 5- and 10-year OS rates were 94.3% and 85.9%, 92.3% and 79.2%, and 91.9% and 80.2% (p = 0.728). Five- and 10-year BRFS was 94.1% and 80.6% (low risk), 86.4% and 70.9% (intermediate), and 85.2% and 71.4% (high) (p = 0.0666). Toxicity included rectitis: grade 1 (G1) (277 pts; 32.6%), G2 (108; 12.7%), and G3 (20; 2.6%) and urethritis: G1 (294; 34.6%); G2 (223; 26.2%), and G3 (11; 1.3%). By dose rate (<76 Gy vs. ≥76 Gy), 5 and 10-year BRFS rates were 83.1% and 68.3% vs. 88.4% and 74.8% (p = 0.038).

CONCLUSIONS

Our results are comparable to other published series in terms of disease control and toxicity. These findings confirm the need for dose escalation to achieve better biochemical control and the benefits of ADT in high-risk PCa patients.

70 Gy versus 80 Gy in localized prostate cancer: 5-year results of GETUG 06 randomized trial

PURPOSE

To perform a randomized trial comparing 70 and 80 Gy radiotherapy for prostate cancer.

PATIENTS AND METHODS

A total of 306 patients with localized prostate cancer were randomized. No androgen deprivation was allowed. The primary endpoint was biochemical relapse according to the modified 1997-American Society for Therapeutic Radiology and Oncology and Phoenix definitions. Toxicity was graded using the Radiation Therapy Oncology Group 1991 criteria and the late effects on normal tissues-subjective, objective, management, analytic scales (LENT-SOMA) scales. The patients' quality of life was scored using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire 30-item cancer-specific and 25-item prostate-specific modules.

RESULTS

The median follow-up was 61 months. According to the 1997-American Society for Therapeutic Radiology and Oncology definition, the 5-year biochemical relapse rate was 39% and 28% in the 70- and 80-Gy arms, respectively (p = .036). Using the Phoenix definition, the 5-year biochemical relapse rate was 32% and 23.5%, respectively (p = .09). The subgroup analysis showed a better biochemical outcome for the higher dose group with an initial prostate-specific antigen level >15 ng/mL. At the last follow-up date, 26 patients had died, 10 of their disease and none of toxicity, with no differences between the two arms. According to the Radiation Therapy Oncology Group scale, the Grade 2 or greater rectal toxicity rate was 14% and 19.5% for the 70- and 80-Gy arms (p = .22), respectively. The Grade 2 or greater urinary toxicity was 10% at 70 Gy and 17.5% at 80 Gy (p = .046). Similar results were observed using the LENT-SOMA scale. Bladder toxicity was more frequent at 80 Gy than at 70 Gy (p = .039). The quality-of-life questionnaire results before and 5 years after treatment were available for 103 patients with no differences found between the 70- and 80-Gy arms.

CONCLUSION

High-dose radiotherapy provided a better 5-year biochemical outcome with slightly greater toxicity.

Radiobiological impact of reduced margins and treatment technique for prostate cancer in terms of tumor control probability (TCP) and normal tissue complication probability (NTCP)

Dose escalation in prostate radiotherapy is limited by normal tissue toxicities. The aim of this study was to assess the impact of margin size on tumor control and side effects for intensity-modulated radiation therapy (IMRT) and 3D conformal radiotherapy (3DCRT) treatment plans with increased dose. Eighteen patients with localized prostate cancer were enrolled. 3DCRT and IMRT plans were compared for a variety of margin sizes. A marker detectable on daily portal images was presupposed for narrow margins. Prescribed dose was 82 Gy within 41 fractions to the prostate clinical target volume (CTV). Tumor control probability (TCP) calculations based on the Poisson model including the linear quadratic approach were performed. Normal tissue complication probability (NTCP) was calculated for bladder, rectum and femoral heads according to the Lyman-Kutcher-Burman method. All plan types presented essentially identical TCP values and very low NTCP for bladder and femoral heads. Mean doses for these critical structures reached a minimum for IMRT with reduced margins. Two endpoints for rectal complications were analyzed. A marked decrease in NTCP for IMRT plans with narrow margins was seen for mild RTOG grade 2/3 as well as for proctitis/necrosis/stenosis/fistula, for which NTCP <7% was obtained. For equivalent TCP values, sparing of normal tissue was demonstrated with the narrow margin approach. The effect was more pronounced for IMRT than 3DCRT, with respect to NTCP for mild, as well as severe, rectal complications.

Choline PET based dose-painting in prostate cancer--modelling of dose effects

BACKGROUND

Several randomized trials have documented the value of radiation dose escalation in patients with prostate cancer, especially in patients with intermediate risk profile. Up to now dose escalation is usually applied to the whole prostate. IMRT and related techniques currently allow for dose escalation in sub-volumes of the organ. However, the sensitivity of the imaging modality and the fact that small islands of cancer are often dispersed within the whole organ may limit these approaches with regard to a clear clinical benefit. In order to assess potential effects of a dose escalation in certain sub-volumes based on choline PET imaging a mathematical dose-response model was developed.

METHODS

Based on different assumptions for alpha/beta, gamma 50, sensitivity and specificity of choline PET, the influence of the whole prostate and simultaneous integrated boost (SIB) dose on tumor control probability (TCP) was calculated. Based on the given heterogeneity of all potential variables certain representative permutations of the parameters were chosen and, subsequently, the influence on TCP was assessed.

RESULTS

Using schedules with 74 Gy within the whole prostate and a SIB dose of 90 Gy the TCP increase ranged from 23.1% (high detection rate of choline PET, low whole prostate dose, high gamma 50/ASTRO definition for tumor control) to 1.4% TCP gain (low sensitivity of PET, high whole prostate dose, CN + 2 definition for tumor control) or even 0% in selected cases. The corresponding initial TCP values without integrated boost ranged from 67.3% to 100%. According to a large data set of intermediate-risk prostate cancer patients the resulting TCP gains ranged from 22.2% to 10.1% (ASTRO definition) or from 13.2% to 6.0% (CN + 2 definition).

DISCUSSION

Although a simplified mathematical model was employed, the presented model allows for an estimation in how far given schedules are relevant for clinical practice. However, the benefit of a SIB based on choline PET seems less than intuitively expected. Only under the assumption of high detection rates and low initial TCP values the TCP gain has been shown to be relevant.

CONCLUSIONS

Based on the employed assumptions, specific dose escalation to choline PET positive areas within the prostate may increase the local control rates. Due to the lack of exact PET sensitivity and prostate alpha/beta parameter, no firm conclusions can be made. Small variations may completely abrogate the clinical benefit of a SIB based on choline PET imaging.

A prediction study on radiation-induced second malignancies for IMRT treatment delivery

Low-level peripheral organ dose and its effect on second malignancies for patients undergoing radiation therapy have been reported in the literature. However, a comprehensive database outlining the treatment modalities, the tumor location, and a quantification of the overall relative risk of second malignancies is rather limited. In this work, we quantify the relative risks or percent likelihood of second malignancies for patients undergoing IMRT and conventional radiotherapy for four different tumor sites: breast, head and neck, lung, and prostate. We utilize Monte Carlo methods based on actual patient plans to compute the whole body effective dose equivalent for each plan and then deduce the percent likelihood of the occurrence of second malignancy. Based on an evaluation of over 30 actual patient plans and Monte Carlo simulations using 6, 10, and 18MV photon beam energies, we observed that the IMRT patients treated for head and neck cancer showed a 40% increase in risk for developing a second malignancy compared to those treated with conventional radiotherapy. The increase in risk for prostrate patients was 30% while the IMRT lung patients gave the highest relative risk almost tripling that observed in their conventionally treated counterparts. There was negligible difference in risk between breast patients undergoing IMRT treatment versus conventional therapy. The overall relative risk of radiation induced malignancy observed was below 6% in all treatment plans considered.

A new fiducial marker for Image-guided radiotherapy of prostate cancer: clinical experience

BACKGROUND

A new fiducial marker for image guided radiotherapy (IGRT) based on a removable prostate stent made of Ni Ti has been developed during two previous clinical feasibility studies. The marker is currently being evaluated for IGRT treatment in a third clinical study.

METHOD

The new marker is used to co-register MR and planning CT scans with high accuracy in the region around the prostate. The co-registered MR-CT volumes are used for delineation of GTV before planning. In each treatment session the IGRT system is used to position the patient before treatment. The IGRT system use a stereo pair of kV images matched to corresponding Digital Reconstructed Radiograms (DRR) from the planning CT scan. The match is done using mutual gray scale information. The pair of DRR's for positioning is created in the IGRT system with a threshold in the Look Up Table (LUT). The resulting match provides the necessary shift in couch coordinates to position the stent with an accuracy of 1-2 mm within the planned position.

RESULTS

At the present time 39 patients have received the new marker. Of the 39 one has migrated to the bladder. Deviations of more than 5 mm between CTV outlined on CT and MR are seen in several cases and in anterior-posterior (AP), left-right (LR) and cranial-caudal (CC) directions. Intra-fraction translation movements up to +/- 3 mm are seen as well. As the stent is also clearly visible on images taken with high voltage x-rays using electronic portal images devices (EPID), the positioning has been verified independently of the IGRT system.

DISCUSSION

The preliminary result of an on going clinical study of a Ni Ti prostate stent, potentially a new fiducial marker for image guided radiotherapy, looks promising. The risk of migration appears to be much lower compared to previous designs.

Salvage radiotherapy after high-intensity focused ultrasound for localized prostate cancer: early clinical results

OBJECTIVES

To evaluate the first results of salvage radiotherapy after high-intensity focused ultrasound (HIFU) in terms of feasibility, tolerance, and oncologic control.

METHODS

From March 1995 to May 2004, 45 patients presenting with local failure after HIFU underwent salvage radiotherapy alone (n = 32) or combined with hormonal therapy (n = 13). The modalities of radiotherapy are described. Tolerance was evaluated using the Radiation Therapy Oncology Group score for urinary and digestive side effects, and incontinence was evaluated using the Ingelman Sundberg score. Patients answered a questionnaire. For the 32 patients who underwent radiotherapy alone, the oncologic early results were given by the disease-free survival rate, defined as no biochemical progression and no androgen suppression therapy.

RESULTS

The median and mean follow-up were 40 and 46 months, respectively, for the whole series. No additional digestive or urinary toxicity developed with salvage radiotherapy after HIFU. The data from 32 patients were evaluated, with a median follow-up of 37 months after radiotherapy. The 5-year disease-free survival rate was 64% for the 32 patients evaluated. The 5-year disease-free survival rate reached 80% for patients treated for positive biopsy findings and was 44% for those with isolated biochemical failure.

CONCLUSIONS

Salvage radiotherapy after HIFU for local recurrence is feasible, with no additional toxicity. The early oncologic results are encouraging when isolated local recurrence is proven but longer follow-up is needed.

Radiothérapie robotisée des cancers de prostate par CyberKnife™

After 3D conformal radiation therapy without and with modulated intensity, image-guided radiation therapy represents a new technological step. Should prostate cancer treatment using radiotherapy with the CyberKnife robotic system be considered as a new treatment and then investigated through classical clinical research procedure rather than a technical improvement of an already validated treatment? After a general presentation of the CyberKnife , the authors focused on prostate cancer treatment assuming that, according to dosimetric and biological considerations, the treatment by robotic system appears comparable to high dose rate brachytherapy. For prostate cancer treatment are discussed: biological rational for hypofractionated treatment, high dose rate brachytherapy boost and interest of dose escalation. A comparison is presented between CyberKnife and other validated treatment for prostate cancer (radical prostatectomy, 3D conformal radiation therapy and low and high dose rate brachytherapy). In summary, CyberKnife treatment could be considered as a technical improvement of an already validated treatment in order to deliver a prostate boost after pelvic or peri-prostatic area irradiation. However, the clinical, biological and economical results must be precisely analyzed and could be assessed in the frame of a National Observatory based on shared therapeutic program.

Monte Carlo determination of radiation-induced cancer risks for prostate patients undergoing intensity- modulated radiation therapy

The application of intensity‐modulated radiation therapy (IMRT) has enabled the delivery of high doses to the target volume while sparing the surrounding normal tissues. The drawbacks of intensity modulation, as implemented using a computer‐controlled multileaf collimator (MLC), are the larger number of monitor units (MUs) and longer beam‐on time as compared with conventional radiotherapy. Additionally, IMRT uses more beam directions—typically 5 – 9 for prostate treatment—to achieve highly conformal dose and normal‐tissue sparing. In the present work, we study radiation‐induced cancer risks attributable to IMRT delivery using MLC for prostate patients.

Whole‐body computed tomography scans were used in our study to calculate (according to report no. 116 from the National Council on Radiation Protection and Measurements) the effective dose equivalent received by individual organs. We used EGS4 and MCSIM to compute the dose for IMRT and three‐dimensional conformal radiotherapy. The effects of collimator rotation, distance from the treatment field, and scatter and leakage contribution to the whole‐body dose were investigated. We calculated the whole‐body dose equivalent to estimate the increase in the risk of secondary malignancies.

Our results showed an overall doubling in the risk of secondary malignancies from the application of IMRT as compared with conventional radiotherapy. This increase in the risk of secondary malignancies is not necessarily related to a relative increase in MUs. The whole‐body dose equivalent was also affected by collimator rotation, field size, and the energy of the photon beam. Smaller field sizes of low‐energy photon beams (that is, 6 MV) with the MLC axis along the lateral axis of the patient resulted in the lowest whole‐body dose. Our results can be used to evaluate the risk of secondary malignancies for prostate IMRT patients.

PACS: 87.53.wz, 87.53.‐j

[Current treatment in high risk and locally advanced prostate cancer]

Treatment of locally advanced prostate cancer remains controversial. Treatment options include radical prostatectomy (PR), radiotherapy (RT) and hormonotherapy (HT). A Medline database search with key words "prostate cancer", "locally advanced", "high risk" and "treatment" in articles published during the last 15 years was done. Fifty one out of 329 papers were selected and reviewed. Selection criteria were a minimum of scientific evidence level of IIa, except for some specific level IV reference. Numerous randomized studies show that patients may benefit of a combined therapy with RT and HT. RP has shown its usefulness in selected cases of locally advanced prostate cancer. Results of long follow-up series are similar to those obtained with RT and HT. Furthermore, the possibility of clinical over staging is an argument in favour of RP. We perform an updated revision of every possible choice available in the treatment of these tumours.

Particle therapy in prostate cancer: a review

While dose escalation is proving important to achieve satisfactory long-term outcomes in prostate cancer, the optimal radiation modality to deliver the treatment is still a topic of debate. Charged particle beams can offer improved dose distributions to the target volume as compared to conventional 3D-conformal radiotherapy, with better sparing of surrounding healthy tissues. Exquisite dose distributions, with the fulfillment of dose-volume constraints to normal tissues, however, can also be achieved with photon-based intensity-modulated techniques. This review summarizes the literature on the use of particle therapy in prostate cancer and attempts to put in perspective its relative merits compared to current photon-based radiotherapy.

Automated detection of a prostate Ni-Ti stent in electronic portal images

Planning target volumes (PTV) in fractionated radiotherapy still have to be outlined with wide margins to the clinical target volume due to uncertainties arising from daily shift of the prostate position. A recently proposed new method of visualization of the prostate is based on insertion of a thermo-expandable Ni-Ti stent. The current study proposes a new detection algorithm for automated detection of the Ni-Ti stent in electronic portal images. The algorithm is based on the Ni-Ti stent having a cylindrical shape with a fixed diameter, which was used as the basis for an automated detection algorithm. The automated method uses enhancement of lines combined with a grayscale morphology operation that looks for enhanced pixels separated with a distance similar to the diameter of the stent. The images in this study are all from prostate cancer patients treated with radiotherapy in a previous study. Images of a stent inserted in a humanoid phantom demonstrated a localization accuracy of 0.4-0.7 mm which equals the pixel size in the image. The automated detection of the stent was compared to manual detection in 71 pairs of orthogonal images taken in nine patients. The algorithm was successful in 67 of 71 pairs of images. The method is fast, has a high success rate, good accuracy, and has a potential for unsupervised localization of the prostate before radiotherapy, which would enable automated repositioning before treatment and allow for the use of very tight PTV margins.

Long-term outcome of high dose intensity modulated radiation therapy for patients with clinically localized prostate cancer

PURPOSE

We report on the long-term results and late toxicity outcomes of high dose intensity modulated radiation therapy for patients with clinically localized prostate cancer.

MATERIALS AND METHODS

Between 1996 and 2000 a total of 561 patients with clinically localized prostate cancer were treated with intensity modulated radiation therapy. All patients were treated to a dose of 81 Gy prescribed to the planning target volume. Prostate specific antigen relapse was defined according to the American Society for Therapeutic Radiology and Oncology consensus and Houston definitions (absolute nadir plus 2 ng/ml dated at the call). Median followup was 7 years (range 5 to 9).

RESULTS

The 8-year actuarial PSA relapse-free survival rates for patients in favorable, intermediate and unfavorable risk groups according to the American Society for Therapeutic Radiology and Oncology definition were 85%, 76% and 72%, respectively (p <0.025). The 8-year actuarial prostate specific antigen relapse-free survival rates for patients in favorable, intermediate and unfavorable risk groups according to the Houston definition were 89%, 78% and 67%, respectively (p = 0.0004). The 8-year actuarial likelihood of grade 2 rectal bleeding was 1.6%. Three patients (0.1%) experienced grade 3 rectal toxicity requiring either 1 or more transfusions or a laser cauterization procedure. No grade 4 rectal complications have been observed. The 8-year likelihood of late grade 2 and 3 (urethral strictures) urinary toxicities were 9% and 3%, respectively. Among patients who were potent before intensity modulated radiation therapy, erectile dysfunction developed in 49%. The cause specific survival outcomes for favorable, intermediate and unfavorable risk cases were 100%, 96% and 84%, respectively.

CONCLUSIONS

These long-term results confirm our previous observations regarding the safety of high dose intensity modulated radiation therapy for clinically localized prostate cancer. Despite the application of high radiation doses, the incidence of rectal bleeding at 8 years was less than 2%. Despite the increased conformality of the dose distribution associated with intensity modulated radiation therapy, excellent long-term tumor control outcomes were achieved.

Radiothérapie conformationnelle du cancer de la prostate : technique et résultats

A number of retrospective and prospective studies have demonstrated that radiotherapy of prostate cancer must be actually conformal. Three-dimensional (3D) treatment planning consists in an as accurate as possible definition of target-volume, usually by CT-scan, and design of radiation fields shaped to this target-volume. Several steps are required, each step being important for the overall quality of the treatment. Conformal radiotherapy is better tolerated than conventional irradiation, with significantly less rectal toxicity. It allows dose-escalation up to 80 Gy. It is now possible to go beyond this dose with intensity-modulated radiotherapy. The benefit of these high doses was demonstrated by some large retrospective studies and some prospective dose-escalation trials. Several randomized trials are in progress, preliminary results of two of them have been published, both showing an improvement in disease control with the higher doses. The advantage of higher doses is clearly evident for patients in the intermediate prognostic group, but is still discussed for patients with a low risk tumour or treated in combination with hormone therapy. Late proctitis is the main toxicity of these high doses. Some volume constraints have been defined during the last years and will allow a decrease of the rate of rectal toxicity. Because of these technological improvements, results of radiation therapy are now similar to those of surgery: no direct comparison with a randomized trial is available, but large comparative studies show that long-term disease control are identical with both techniques. Radiation therapy must be proposed to all patients with a prostate carcinoma as an alternative to surgery.

Dose-Response in Radiotherapy for Localized Prostate Cancer: Results of the Dutch Multicenter Randomized Phase III Trial Comparing 68 Gy of Radiotherapy With 78 Gy

Purpose

To determine whether a dose of 78 Gy improves outcome compared with a conventional dose of 68 Gy for prostate cancer patients treated with three-dimensional conformal radiotherapy.

Patients and Methods

Between June 1997 and February 2003, stage T1b-4 prostate cancer patients were enrolled onto a multicenter randomized trial comparing 68 Gy with 78 Gy. Patients were stratified by institution, age, (neo)adjuvant hormonal therapy (HT), and treatment group. Four treatment groups (with specific radiation volumes) were defined based on the probability of seminal vesicle involvement. The primary end point was freedom from failure (FFF). Failure was defined as clinical failure or biochemical failure, according to the American Society of Therapeutic Radiation Oncology definition. Other end points were freedom from clinical failure (FFCF), overall survival (OS), and toxicity.

Results

Median follow-up time was 51 months. Of the 669 enrolled patients, 664 were included in the analysis. HT was prescribed for 143 patients. FFF was significantly better in the 78-Gy arm compared with the 68-Gy arm (5-year FFF rate, 64% v 54%, respectively), with an adjusted hazard ratio of 0.74 (P = .02). No significant differences in FFCF or OS were seen between the treatment arms. There was no difference in late genitourinary toxicity of Radiation Therapy Oncology Group and European Organisation for Research and Treatment of Cancer grade 2 or more and a slightly higher nonsignificant incidence of late gastrointestinal toxicity of grade 2 or more.

Conclusion

This multicenter randomized trial shows a significantly improved FFF in prostate cancer patients treated with a higher dose of radiotherapy.

Radiothérapie pelvienne pour récidive biochimique isolée après prostatectomie pour cancer de prostate : quels volumes ?

After prostatectomy, radiotherapy is a potential curable treatment. From the surgery series, it is possible to identify all the localization at risk in case of biochemical relapse after prostatectomy. The target volume of irradiation has to be defined according to the pathological findings. The CTV is limited to the pelvic fascia laterally, to the anterior wall of the rectum behind. The inferior limit includes the anastomosis, and the superior is easier to define with the length of the prostatic gland. The inclusion of area of seminal vesicles and pelvic node areas should be discussed. The use of surgical clips on the anastomosis and image fusionning techniques including the preoperative imaging would help physicians to define the CTV's limits.

Feasibility study using a Ni–Ti stent and electronic portal imaging to localize the prostate during radiotherapy

BACKGROUND AND PURPOSE

A new method for localization of the prostate during external beam radiotherapy is presented. The method is based on insertion of a thermo-expandable Ni-Ti stent. The stent is originally developed for treatment of bladder outlet obstruction caused by benign hyperplasia. The radiological properties of the stent are used for precise prostate localization during treatment using electronic portal images.

PATIENTS AND METHODS

Patients referred for intended curative radiotherapy and having a length of their prostatic urethra in the range from 25 to 65 mm were included. Pairs of isocentric orthogonal portal images were used to determine the 3D position at eight different treatment sessions for each patient.

RESULTS

Fourteen patients were enrolled in the study. The data obtained demonstrated that the stent position was representative of the prostate location. The stent may also improve delineation of the prostate GTV, and prevent obstruction of bladder outlet during treatment. Precision in localization of the stent was less than 1 mm. Random errors in stent position were left-right 1.6 mm, cranial-caudal 2.2 mm and anterior-posterior 3.2 mm. In four of 14 patients a dislocation of the stent to the bladder occurred. Dislocation only occurred in patients with length of prostatic urethra less than 40 mm.

CONCLUSIONS

A new method for radiological high precision localization of the prostate during radiotherapy is presented. The method is based on insertion of a standard Ni-Ti thermo-expandable stent, designed for treatment of benign prostate hyperplasia.

70 Gy or more: which dose for which prostate cancer?

INTRODUCTION

Radical prostatectomy and radiotherapy are currently accepted treatment modalities for localized prostate cancer. Regarding radiotherapy, current evidence suggests that favorable treatment outcome critically depends on adequate radiation doses. However, the exact role of dose in relation to the individual risk profile is complex. In order to evaluate available data on radiation dose response relationships, in prostate cancer, a thorough and critical literature analysis was performed.

MATERIAL AND METHODS

Studies on dose response relationships from randomized trials, dose escalation trials, retrospective subgroup analyses and pooled data were identified by Pubmed and ISI web of sciences searches and were critically reviewed.

RESULTS AND CONCLUSION

All available data suggest a clear dose response relationship for radiotherapy for localized prostate cancer. In low risk cases, most studies suggest that doses of 70-72 Gy are adequate. Dose escalations up to 78-80 Gy seem to be beneficial for intermediate risk patients. Due to confounding variables, the dose response curves for high-risk patients are less steep. The integration of dose escalation into a more comprehensive treatment protocol is difficult, since trials on the relative impact of either hormonal ablation or inclusion of adjuvant nodal regions on dose escalation are missing.

Evidence-based review of three-dimensional conformal radiotherapy for localized prostate cancer: An ASTRO outcomes initiative

PURPOSE

To perform a systematic review of the evidence to determine the efficacy and effectiveness of three-dimensional conformal radiotherapy (3D-CRT) for localized prostate cancer; provide a clear presentation of the key clinical outcome questions related to the use of 3D-CRT in the treatment of localized prostate cancer that may be answered by a formal literature review; and provide concise information on whether 3D-CRT improves the clinical outcomes in the treatment of localized prostate cancer compared with conventional RT.

METHODS AND MATERIALS

We performed a systematic review of the literature through a structured process developed by the American Society for Therapeutic Radiology and Oncology's Outcomes Committee that involved the creation of a multidisciplinary task force, development of clinical outcome questions, a formal literature review and data abstraction, data review, and outside peer review.

RESULTS

Seven key clinical questions were identified. The results and task force conclusions of the literature review for each question are reported.

CONCLUSION

The technological goals of reducing morbidity with 3D-CRT have been achieved. Randomized trials and follow-up of completed trials remain necessary to address these clinical outcomes specifically with regard to patient subsets and the use of hormonal therapy.

Acute and late complications after radiotherapy for prostate cancer: results of a multicenter randomized trial comparing 68 Gy to 78 Gy

PURPOSE

To compare acute and late gastrointestinal (GI) and genitourinary (GU) side effects in prostate cancer patients randomized to receive 68 Gy or 78 Gy.

METHODS AND MATERIALS

Between June 1997 and February 2003, 669 prostate cancer patients were randomized between radiotherapy with a dose of 68 Gy and 78 Gy, in 2 Gy per fraction and using three-dimensional conformal radiotherapy. All T stages with prostate-specific antigen (PSA) <60 ng/mL were included, except any T1a and well-differentiated T1b-c tumors with PSA < or =4 ng/mL. Stratification was done for four dose-volume groups (according to the risk of seminal vesicles [SV] involvement), age, hormonal treatment (HT), and hospital. The clinical target volume (CTV) consisted of the prostate with or without the SV, depending on the estimated risk of SV invasion. The CTV-planning target volume (PTV) margin was 1 cm for the first 68 Gy and was reduced to 0.5 cm (0 cm toward the rectum) for the last 10 Gy in the 78 Gy arm. Four Dutch hospitals participated in this Phase III trial. Evaluation of acute and late toxicity was based on 658 and 643 patients, respectively. For acute toxicity (<120 days), the Radiation Therapy Oncology Group (RTOG) scoring system was used and the maximum score was reported. Late toxicity (>120 days) was scored according to the slightly adapted RTOG/European Organization for Research and Treatment of Cancer (EORTC) criteria.

RESULTS

The median follow-up time was 31 months. For acute toxicity no significant differences were seen between the two randomization arms. GI toxicity Grade 2 and 3 was reported as the maximum acute toxicity in 44% and 5% of the patients, respectively. For acute GU toxicity, these figures were 41% and 13%. No significant differences between both randomization arms were seen for late GI and GU toxicity, except for rectal bleeding requiring laser treatment or transfusion (p = 0.007) and nocturia (p = 0.05). The 3-year cumulative risk of late RTOG/EORTC GI toxicity grade > or =2 was 23.2% for 68 Gy, and 26.5% for 78 Gy (p = 0.3). The 3-year risks of late RTOG/EORTC GU toxicity grade > or =2 were 28.5% and 30.2% for 68 Gy and 78 Gy, respectively (p = 0.3). Factors related to acute GI toxicity were HT (p < 0.001), a higher dose-volume group (p = 0.01), and pretreatment GI symptoms (p = 0.04). For acute GU toxicity, prognostic factors were: pretreatment GU symptoms (p < 0.001), HT (p = 0.003), and prior transurethral resection of the prostate (TURP) (p = 0.02). A history of abdominal surgery (p < 0.001) and pretreatment GI symptoms (p = 0.001) were associated with a higher incidence of late GI grade > or =2 toxicity, whereas HT (p < 0.001), pretreatment GU symptoms (p < 0.001), and prior TURP (p = 0.006) were prognostic factors for late GU grade > or =2.

CONCLUSIONS

Raising the dose to the prostate from 68 Gy to 78 Gy resulted in higher incidences of acute and late GI and GU toxicity, but these differences were not significant, except for late rectal bleeding requiring treatment and late nocturia. Other factors than the studied dose levels appeared to be important in predicting toxicity after radiotherapy, especially previous surgical interventions (abdominal surgery or TURP), hormonal therapy, and the presence of pretreatment symptoms.

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

Radical radiotherapy is a standard form of management of localised prostate cancer. Conformal treatment planning spares adjacent normal tissues reducing treatment-related side effects and may permit safe dose escalation. We have tested the effects on tumour control and side effects of escalating radiotherapy dose and investigated the appropriate target volume margin. After an initial 3-6 month period of androgen suppression, 126 men were randomised and treated with radiotherapy using a 2 by 2 factorial trial design. The initial radiotherapy tumour target volume included the prostate and base of seminal vesicles (SV) or complete SV depending on SV involvement risk. Treatments were randomised to deliver a dose of 64 Gy with either a 1.0 or 1.5 cm margin around the tumour volume (1.0 and 1.5 cm margin groups) and also to treat either with or without a 10 Gy boost to the prostate alone with no additional margin (64 and 74 Gy groups). Tumour control was monitored by prostate-specific antigen (PSA) testing and clinical examination with additional tests as appropriate. Acute and late side effects of treatment were measured using the Radiation Treatment and Oncology Groups (RTOG) and LENT SOM systems. The results showed that freedom from PSA failure was higher in the 74 Gy group compared to the 64 Gy group, but this did not reach conventional levels of statistical significance with 5-year actuarial control rates of 71% (95% CI 58-81%) in the 74 Gy group vs 59% (95% CI 45-70%) in the 64 Gy group. There were 23 failures in the 74 Gy group and 33 in the 64 Gy group (Hazard ratio 0.64, 95% CI 0.38-1.10, P=0.10). No difference in disease control was seen between the 1.0 and 1.5 cm margin groups (5-year actuarial control rates 67%, 95% CI 53-77% vs 63%, 95% CI 50-74%) with 28 events in each group (Hazard ratio 0.97, 95% CI 0.50-1.86, P=0.94). Acute side effects were generally mild and 18 weeks after treatment, only four and five of the 126 men had persistent > or =Grade 1 bowel or bladder side effects, respectively. Statistically significant increases in acute bladder side effects were seen after treatment in the men receiving 74 Gy (P=0.006), and increases in both acute bowel side effects during treatment (P=0.05) and acute bladder sequelae (P=0.002) were recorded for men in the 1.5 cm margin group. While statistically significant, these differences were of short duration and of doubtful clinical importance. Late bowel side effects (RTOG> or =2) were seen more commonly in the 74 Gy and 1.5 cm margin groups (P=0.02 and P=0.05, respectively) in the first 2 years after randomisation. Similar results were found using the LENT SOM assessments. No significant differences in late bladder side effects were seen between the randomised groups using the RTOG scoring system. Using the LENT SOM instrument, a higher proportion of men treated in the 74 Gy group had Grade > or =3 urinary frequency at 6 and 12 months. Compared to baseline scores, bladder symptoms improved after 6 months or more follow-up in all groups. Sexual function deteriorated after treatment with the number of men reporting some sexual dysfunction (Grade> or =1) increasing from 38% at baseline to 66% at 6 months and 1 year and 81% by year 5. However, no consistent differences were seen between the randomised groups. In conclusion, dose escalation from 64 to 74 Gy using conformal radiotherapy may improve long-term PSA control, but a treatment margin of 1.5 cm is unnecessary and is associated with increased acute bowel and bladder reactions and more late rectal side effects. Data from this randomised pilot study informed the Data Monitoring Committee of the Medical Research Council RT 01 Trial and the two studies will be combined in subsequent meta-analysis.

Comparison of late rectal toxicity from conventional versus three-dimensional conformal radiotherapy for prostate cancer: Analysis of clinical and dosimetric factors

OBJECTIVES

To compare late rectal toxicity (LRT) after definitive radiotherapy (DR) and salvage radiotherapy (SR) in prostate cancer using conventional (CONV) or three-dimensional conformal (3-D) techniques.

METHODS

The outcomes and clinical factors of 212 patients with Stage T1a-T4 prostate cancer were evaluated (separated into DR and SR groups). The median prescribed dose was 66, 74, 66, and 70 Gy, for the CONV-DR, 3-D-DR, CONV-SR, and 3-D-SR groups, respectively. LRT was scored using both Radiation Therapy Oncology Group (RTOG) and modified RTOG and Late Effects Normal Tissue (mRTOG/LENT) scales.

RESULTS

The 4-year biochemical relapse-free survival rate was 83% for all patients, with a trend toward improvement in the 3-D groups (78% CONV and 85% 3-D, P = 0.12). One patient (1%) in the CONV group and 24 (24%) in the 3-D group experienced grade 2 or worse LRT by the mRTOG/LENT scale. Patients undergoing DR experienced grade 2 or worse LRT of 1% versus 21% (P = 0.003) for the CONV and 3-D groups, respectively. Patients undergoing SR experienced grade 2 or worse LRT of 0% versus 40% for the CONV and 3-D groups, respectively. The following variables correlated significantly with LRT on both univariate and multivariate analyses: prescribed radiation dose (P <0.0001), percentage of rectal volume receiving 60 Gy (P <0.005), and percentage of rectal volume receiving 70 Gy (P <0.001). The pretreatment clinical factors, when added to the dosimetric data, were not statistically significant on multivariate analysis (P >0.05).

CONCLUSIONS

The prescribed radiation dose and percentage of rectal volume treated to 60 or 70 Gy had statistically significant correlations with increased LRT. The rate of grade 2 or worse LRT was greater for patients undergoing SR than for those undergoing DR. We believe that continued close attention to dosimetric variables is imperative for future studies of dose escalation.

High conformality radiotherapy in Europe: thirty-one centres participating in the quality assurance programme of the EORTC prostate trial 22991

Today, conformality in radiotherapy is at the centre of many investments in equipment and staffing. To estimate the current situation within the European Organisation for Research and Treatment of Cancer (EORTC) conformal radiotherapy trial for prostate cancer, a technology questionnaire was designed to assess whether participating centres can comply with the required radiotherapy procedures of EORTC trial 22991, where a high dose is prescribed to the prostate. Questions covered various items of computed tomography, data acquisition, treatment planning, delivery and verification. All centres (n=31) replied to the questionnaire. All generate beam's eye views and dose volume histograms. All, but two, centres use digitally reconstructed radiographs to display images. The vast majority of the centres perform at least weekly treatment verification and half have access to individual in vivo dosimetry. The results of the questionnaire indicate that participating centres have access to the equipment and apply the procedures that are essential for conformal prostate radiotherapy. The technology questionnaire is the first step in the extensive quality assurance programme dedicated to this high-tech radiotherapy trial.

Choix des contraintes et amélioration dosimétrique d’une radiothérapie conformationnelle du cancer de la prostate modulée en intensité pendant une partie du traitement

PURPOSE

Intensity modulated radiation therapy (IMRT) is based on a methodology called inverse planning. Starting from dosimetric objectives, constraints of optimization are fixed and given to the inverse planning system, which in turn calculates the modulated intensity to apply to each beam. Since the algorithms allow the constraints to be violated, the results of optimization may differ from the initial dosimetric objectives. Consequently, the user is compelled to adapt the choice of the constraints according to the type of modulation and until satisfactory results are found. The purpose of this work is to present our experience in the choice of these constraints for prostate cancer treatments, as we moved from conformal radiotherapy to IMRT. Treatments were performed with a Varian 23EX linac and calculations were realized with the Varian CadPlan-Helios planning system.

PATIENTS AND METHODS

The approach used for the first 12 patients treated at institut Curie with IMRT from June 2002 was analysed. The treatment always consisted of a combination of conformal radiotherapy with and without intensity modulation.

RESULTS AND CONCLUSION

Results showed that, a larger fraction of the treatment performed with IMRT induced a better sparing of the organs at risk for the same homogeneous dose distribution to the target volume. Apart from the dose-volume constraint for the rectum, a fixed set of constraints, slightly more restrictive than the dosimetric objectives, could be used for all patients. Compared with conformal radiotherapy, the conformation factor for IMRT increased up to 16%. A specific study was undertaken in view of treatments completely performed with IMRT. The optimal technique consisted in performing separated IMRT plans for the two target volumes, the prostate volume and the prostate plus seminal vesicles volume respectively. Another satisfactory possibility was to define new constraints on two separated planning target volumes, prostate and seminal vesicles. This last approach is now routinely implemented for our IMRT patients.

The GETUG 70 Gy vs. 80 Gy randomized trial for localized prostate cancer: feasibility and acute toxicity

PURPOSE

To describe treatments and acute tolerance in a randomized trial comparing 70 Gy and 80 Gy to the prostate in patients with localized prostate cancer.

METHODS AND MATERIALS

Between September 1999 and February 2002, 306 patients were randomized to receive 70 Gy (153 patients) or 80 Gy (153 patients) in 17 institutions. Patients exhibited intermediate-prognosis tumors. If the risk of node involvement was greater than 10%, surgical staging was required. Previous prostatectomy was excluded, and androgen deprivation was not admitted. The treatment was delivered in two steps. PTV1-including seminal vesicles, prostate, and a 1-0.5-cm margin-received 46 Gy given with a 4-field conformal technique. PTV2, reduced to prostate with the same margins, irradiated with at least 5 fields. Dose was prescribed according to ICRU recommendations in the 70 Gy group, but adapted at the 80 Gy level.

RESULTS

All patients but one in the 80 Gy arm completed the treatment. In the 70 Gy arm, the mean dose to the PTV2 was 69.5 Gy. In the 80 Gy arm, the mean dose in the PTV2 was 78.5 Gy. Acute toxicity according to Radiation Therapy Oncology Group scale during treatment was reported in 306 patients. There was no statistically significant difference between the two arms: 12% had no toxicity, 80% complained of bladder toxicity, and 70% complained of rectal symptoms. Two months after the end of treatment, 43% of the 70 Gy level and 48% of the 80 Gy level complained of side effects, including 24% and 20% of sexual disorders. There was 6% and 2% of Grade 3 urinary and rectal toxicity. Five patients required a 10-29-day suspension of the treatment. Acute Grade 2 and 3 side effects were related to PTV and CTV1 size, which was the only independent predictive factor in multivariate analysis. Toxicity was not related to the center, age, arm of treatment, or selected data from dose-volume histogram of organ at risk.

CONCLUSION

Treatments were completed in respect to constraints. Acute toxicity was acceptable. Intensity of toxicity depended on target volumes.

Clinical and physical quality assurance for intensity modulated radiotherapy of prostate cancer

The implementation of intensity modulated radiotherapy (IMRT) for patients with prostate cancer in daily routine has been elaborated at our department. Our quality assurance (QA) concept is one method to pave the way for initiating IMRT treatments for starting institutions. A clinical quality assurance (CQA) procedure has been set-up for all patients before and throughout the course of radiotherapy. Simultaneously medical physicists established a physical quality assurance (PQA) concept that has been followed for all patients as well. Alternative CQA and PQA procedures are discussed. The literature is reviewed and discussed with special respect to quality assurance in IMRT of prostate cancer patients.

Enhanced radiosensitivity of rat autochthonous mammary tumors by dietary docosahexaenoic acid

Dietary docosahexaenoic acid (DHA), which integrates into tumor cell membranes, has been reported to enhance the efficacy against tumors of cytotoxic drugs that induce reactive oxygen species (ROS). Because ionizing radiation also generate ROS, we initiated a study to determine whether dietary DHA might sensitize mammary tumors to irradiation. Mammary tumors were induced by N-methylnitrosourea (NMU) in Sprague-Dawley rats. The optimal dose of radiation to examine the effect of DHA on tumor response to irradiation was determined to be 18 grays (Gy) using a 4-6 MeV electron beam (according to the depth of the target volume) delivered in a single fraction from a linear accelerator. Two groups of rats were fed a basal diet containing 7% of a mixture of peanut and rapeseed oils enriched with 8% of an oil containing either a low (palm oil) or high (DHASCO oil containing 40% DHA) DHA content. DHA group was equally subdivided into 2 groups without or with addition of vitamin E (100 IU/kg diet). Irradiation was carried out when the first tumor in each rat reached 1.5 cm2 and subsequent change in tumor size was documented over time. DHA level in adipose tissue, taken as a biomarker, was higher in the DHA supplemented group compared to the control group. Vitamin E level in liver, the best storage for this compound, was higher in the vitamin E supplemented DHA group compared to the DHA group. Tumor size decreased by 60% at 12 days after irradiation in the DHA group vs. 31% in the control group (p = 0.03) and 36% in the DHA plus vitamin E group. Therefore, dietary DHA sensitized mammary tumors to radiation. The addition of vitamin E inhibited the beneficial effect of DHA, suggesting that this effect might be mediated by oxidative damage to the peroxidizable lipids.

Treatment outcomes of three-dimensional conformal radiotherapy for localized prostate carcinoma

BACKGROUND

The current study documented the implementation of three-dimensional conformal radiotherapy and assessed the tumor control and toxicity of such treatment in a large, multisite community practice.

METHODS

The authors retrospectively reviewed their first 222 consecutive patients with clinically localized (N0) prostate carcinoma treated with a 6-field conformal technique from October 1993 through March 2000. Standardized target definitions, dose planning constraints, and gantry angles were utilized to develop the treatment plan. Patients were categorized by low, intermediate, and high risk. Low risk was defined as T1a-T2a disease, a Gleason score < 7, and prostate-specific antigen (PSA) level </= 10.0 ng/mL (n = 47 [21%]). Intermediate risk was defined as T2b disease, a Gleason score > 6, or PSA level > 10.01 ng/mL (n = 60 [27%]). High risk was defined as 2 of the above risk factors or as T3 disease, a Gleason score > 7, or a PSA level > 20 (n = 115 [52%]). Biochemical disease recurrence was defined in accordance with the American Society for Therapeutic Radiology and Oncology definition. Urinary and bowel toxicity were graded using the Radiation Therapy Oncology Group morbidity scoring system.

RESULTS

The median follow-up after radiotherapy for surviving patients was 47 months (range, 0-99 months). The 2 and 5-year actuarial biochemical control rates for all patients were 84% and 78%, respectively. Using logistic regression analysis, lower dose (< 75.6 gray [Gy] vs. 75.6 Gy; P = 0.006), higher risk group (P = 0.033), higher stage (P = 0.045), and higher PSA level (P = 0.001) were significantly associated with biochemical disease recurrence. Toxicity was not significantly correlated with a higher radiotherapy dose.

CONCLUSIONS

Dose escalation to 75.6 Gy using a 6-field conformal technique was feasible in the authors' community practice and resulted in acceptable toxicity and early biochemical outcomes.

Evaluation of therapeutic potential of heavy ion therapy for patients with locally advanced prostate cancer

PURPOSE

To investigate the feasibility of raster scanned heavy charged particle therapy in the treatment of prostate cancer (PCa,) with special regard to the influence of internal organ motion on the dose distribution.

METHODS AND MATERIALS

The CT data of 8 patients with PCa who underwent three-dimensional conformal radiotherapy (RT) were chosen. In addition to the routine treatment planning scan, three to five additional positioning control CT scans were performed. The organs at risk and the target volumes were defined on all CT scans. Primary and boost carbon ion plans were calculated to deliver 66 Gy to the clinical target volume/planning target volume, with an additional 10 Gy to the gross tumor volume (GTV). To estimate the influence of internal organ motion on plan quality, the dose was recalculated on the basis of the control CT scans. The comparative analysis was based on the dose-volume histogram-derived physical parameters.

RESULTS

The average 90% target coverage was 99.1% for the GTV. The maximal dose to the rectum was 71.8 Gy. The average rectal mean dose was 19 Gy. The volume of the rectum receiving 70 and 68 Gy was 0.1 and 0.3 cm3. The average difference in the 90% coverage for the GTV on control CT cubes was 3.6%. The maximal rectal dose increased to 76.2 Gy. The deviation in the mean rectal dose was <1 Gy on average. The rectal volume receiving 70 and 68 Gy increased to 2.5 and 3.3 cm3.

CONCLUSION

The investigation demonstrated the feasibility of raster scanned carbon ions for PCa RT. Excellent coverage of the target volume and optimal sparing of the rectum were acquired. The combination of photon intensity-modulated RT and a carbon ion boost to the GTV is the most rational solution for the gain of clinical experience in heavy ion RT for PCa patients.

Does short-term androgen deprivation substitute for radiation dose in the treatment of high-risk prostate cancer?

PURPOSE

Randomized trials have corroborated the clinical benefit of adding androgen deprivation (AD) to radiotherapy (RT) in the treatment of high-risk prostate cancer. Another competing strategy is to escalate the RT dose using three-dimensional conformal RT (3D-CRT). In this analysis, we asked whether the addition of short-term AD (STAD) (<or=6 months) to RT in the treatment of high-risk (prostate-specific antigen >20 ng/mL, Gleason score 8-10, or T3-4) prostate cancer is an effective substitute for dose escalation.

METHODS AND MATERIALS

Between March 1, 1990 and November 30, 1998, 296 high-risk prostate cancer patients were treated with 3D-CRT alone (n = 206) or in combination with STAD (n = 90). The patient characteristics were median age 68 years, median follow-up 58 months, pretreatment initial prostate-specific antigen 21.8 ng/mL, RT dose 75 Gy, STAD duration 3 months, and time off STAD 64 months. The impact of STAD with respect to dose was examined using univariate analysis for dose ranges of <75 Gy and >or=75 Gy. Stepwise Cox proportional hazards regression multivariate analysis was performed to determine independent correlates of freedom from biochemical failure (bNED), freedom from distant metastasis (FDM), and overall survival. In a separate matched-pair analysis (n = 44 per group), those treated to <75 Gy + STAD (Group A) were compared with those who received >or=75 Gy alone (Group B).

RESULTS

On univariate analysis, the addition of STAD had no impact on bNED, FDM, or overall survival in either dose group. On multivariate analysis, initial prostate-specific antigen level, palpation T stage, and RT dose were significant correlates of bNED. For FDM and overall survival, the significant covariates were palpation T stage and Gleason score, respectively. Finally, in matched-pair analysis, the higher RT dose group had a significantly greater bNED rate at 5 years (Group A 35% vs. Group B 57%, p = 0.0190).

CONCLUSION

Our data suggest that STAD, as used here (median 3 months), is not a substitute for RT dose in the treatment of high-risk prostate cancer. RT dose is an essential element in the treatment of high-risk prostate cancer.

Introducing a prognostic score for pretherapeutic assessment of seminal vesicle invasion in patients with clinically localized prostate cancer

PURPOSE

To identify prostate cancer patients who will have the most likely benefit from sparing the seminal vesicles during 3D conformal radiation therapy.

METHODS AND MATERIALS

From 1988 to 2001, 532 patients underwent radical prostatectomy for clinically localized prostate cancer. Primary endpoint was the pathological evidence of seminal vesicle invasion. Variables for univariate and multivariate analyses were age, prostate weight, clinical stage, PSA level, Gleason score, number and site of positive prostate sextant biopsies. Multivariate logistic regression with backward stepwise variable selection was used to identify a set of independent predictors of seminal vesicle invasion, and the variable selection procedure was validated by non-parametric bootstrap.

RESULTS

Seminal vesicle invasion was reported in 14% of the cases. In univariate analysis, all variables except age and prostate weight were predictors of seminal vesicle invasion. In multivariate analysis, only the number of positive biopsies (P<0.0001), Gleason score (P<0.007) and PSA (P<0.0001) were predictors for seminal vesicles invasion. Based on the multivariate model, we were able to develop a prognostic score for seminal vesicle invasion, which allowed us to discriminate two patient groups: A group with low risk of seminal vesicles invasion (5.7%), and the second with a higher risk of seminal vesicles invasion (32.7%).

CONCLUSIONS

Using the number of positive biopsies, Gleason score and PSA, it is possible to identify patients with low risk of seminal vesicles invasion. In this population, seminal vesicles might be excluded as a target volume in radiation therapy of prostate cancer.

Prediction of the benefits from dose-escalated hypofractionated intensity-modulated radiotherapy for prostate cancer

PURPOSE

To estimate the benefits of dose escalation in hypofractionated intensity-modulated radiotherapy (IMRT) for prostate cancer, using radiobiologic modeling and incorporating positional uncertainties of organs.

MATERIALS AND METHODS

Biologically based mathematical models for describing the relationships between tumor control probability (TCP) and normal-tissue complication probability (NTCP) vs. dose were used to describe some of the results available in the literature. The values of the model parameters were then used together with the value of 1.5 Gy for the prostate cancer alpha/beta ratio to predict the responses in a hypofractionated 3 Gy/fraction IMRT trial at the Christie Hospital, taking into account patient movement characteristics between dose fractions.

RESULTS

Compared with the current three-dimensional conformal radiotherapy technique (total dose of 50 Gy to the planning target volume in 16 fractions), the use of IMRT to escalate the dose to the prostate was predicted to increase the TCP by 5%, 16%, and 22% for the three dose levels, respectively, of 54, 57, and 60 Gy delivered using 3 Gy per fraction while keeping the late rectal complications (>/=Grade 2 RTOG scale) at about the same level of 5%. Further increases in TCP could be achieved by reducing the uncertainty in daily target position, especially for the last stage of the trial, where up to 6% further increase in TCP should be gained.

CONCLUSIONS

Dose escalation to the prostate using IMRT to deliver daily doses of 3 Gy was predicted to significantly increase tumor control without increasing late rectal complications, and currently this prediction is being tested in a clinical trial.

Preliminary evaluation of low-grade toxicity with conformal radiation therapy for prostate cancer on RTOG 9406 dose levels I and II

PURPOSE

To evaluate the rates of low-grade late effects in patients treated for prostate cancer on Radiation Therapy Oncology Group (RTOG) 9406.

MATERIALS AND METHODS

Between August 1994 and September 1999, 424 patients were entered on this dose escalation trial of three-dimensional conformal radiation therapy (3D-CRT) for localized adenocarcinoma of the prostate at doses of 68.4 Gy (level I) and 73.8 Gy (level II). We have previously reported Grade 3 or greater late toxicity of patients treated on the first two dose levels of this trial. This analysis examines the distribution of all late toxicities in these patients. All radiation prescriptions were a minimum dose to a planning target volume (PTV). Patients were stratified according to clinical stage and risk of seminal vesicle invasion (SVI) based upon Gleason score and presenting prostate-specific antigen. Group 1 includes patients with T1,2 disease with SVI risk < 15%, and Group 2 includes patients with T1,2 disease with SVI risk > 15%. Group 3 patients had T3 disease. Average months at risk after completion of therapy ranged from 21.4 to 40.1 months for patients treated at dose level I and 10.0 to 34.2 months for patients at dose level II. The frequency of all grades of late effects was compared with a similar group of patients treated in RTOG studies 7506 and 7706 with adjustments made for the interval from completion of therapy. The RTOG toxicity scoring scales for late effects were used for grading.

RESULTS

The rate of Grade 3 or greater late toxicity continues to be low compared with RTOG historical controls. No Grade 4 or 5 late sequelae were reported in any of the 393 evaluable patients during the period of observation. The frequency of patients free of any complications was lower in RTOG 9406 than in historical controls. In the 73 Group 1 patients treated on dose level 1, there were 24 patients without sequelae compared with an expected rate of 39.7 (p = 0.013), and in 80 Group 3 patients at dose level II there were 24 patients without sequelae when 56.2 were expected (p < 0.0001). Other groups treated at these dose levels demonstrated a nonsignificant reduction in the rate of patients free of any side effects. These data suggest that the reduction in high-grade morbidity may be related to a shift of complications to lower grades.

CONCLUSIONS

Morbidity of 3D-CRT in the treatment of prostate cancer is low. It is important to continue to closely examine late effects in patients treated in RTOG 9406. The primary objective of dose escalation without an increase rate of >/= Grade 3 sequelae has been achieved. However, the reduction in Grade 3 complications may have resulted in a higher incidence of Grade 1 or 2 late effects. Because Grade 2 late effects may have a significant impact on a patient's quality of life, it is important to reduce these complications as much as possible. Clinical trials should use quality-of-life measures to determine that trade-offs between severity and rates of toxicity are acceptable to patients.

A structured literature review to determine the use of the American Society for Therapeutic Radiology and Oncology consensus definition of biochemical failure

OBJECTIVES

The American Society for Therapeutic Radiology and Oncology consensus definition (ACD) of biochemical failure after radiotherapy for prostate cancer requires three consecutive prostate-specific antigen increases from a nadir value. The members of the Consensus Panel recognized that the timing and frequency of prostate-specific antigen determinations could affect the comparability among different reports if this definition was used. For this reason, the Consensus Panel members recommended three guidelines for studies presented for publication (publication guidelines [PGs]). The present analysis examined the extent to which the ACD has been used in the peer-reviewed published literature and how frequently the PGs have been followed.

METHODS

A structured literature review of 10 relevant journals was done. The inclusion criteria for the literature review required publication in calendar year 1999 or 2000; treatment with external beam radiotherapy and/or brachytherapy for previously untreated, nonmetastatic prostate cancer; and the use of a prostate-specific antigen-defined disease-free endpoint. A standardized checklist was created and completed by both of the authors. We independently reviewed each publication to determine whether the ACD of biochemical failure was used and whether the PGs were followed. Discrepancies between us were resolved by joint review of each publication in question to achieve a consensus.

RESULTS

Fifty-seven articles met the inclusion criteria. The median number of patients in the articles reviewed was 302 (range 22 to 2222). The ACD was followed in 37 (64.9%) of 57 articles. None of the reviewed articles followed all three PGs. In five articles (8.7%), two of the three PGs were followed. The vast majority of the articles reviewed (52 of 57, 91.3%) followed one or none of the PGs recommended by the Consensus Panel.

CONCLUSIONS

The ACD was used in two thirds of peer-reviewed published articles. The PGs were followed much less frequently. Consistent standards of reporting have not been uniformly applied to peer-reviewed manuscripts.

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.

[Target-volume and critical-organ delineation for conformal radiotherapy of prostate cancer: experience of French dose-escalation trials]

The delineation of target volume and organs at risk depends on the organs definition, and on the modalities for the CT-scan acquisition. Inter-observer variability in the delineation may be large, especially when patient's anatomy is unusual. During the two french multicentric studies of conformal radiotherapy for localized prostate cancer, it was made an effort to harmonize the delineation of the target volumes and organs at risk. Two cases were proposed for delineation during two workshops. In the first case, the mean prostate volume was 46.5 mL (extreme: 31.7-61.3), the mean prostate and seminal vesicles volume was 74.7 mL (extreme: 59.6-80.3), the rectal and bladder walls varied respectively in proportion from 1 to 1.45 and from 1 to 1.16; in the second case, the mean prostate volume was 53.1 mL (extreme: 40.8-73.1), the volume of prostate plus seminal vesicles was 65.1 mL (extreme: 53.2-89), the rectal wall varied proportionally from 1 to 1, 24 and the vesical wall varied from 1 to 1.67. For participating centers to the french studies of dose escalation, a quality control of contours was performed to decrease the inter-observer variability. The ways to reduce the discrepancies of volumes delineation, between different observers, are discussed. A better quality of the CT images, use of urethral opacification, and consensual definition of clinical target volumes and organs at risk may contribute to that improvement.

Dose response in prostate cancer with 8–12 years’ follow-up

PURPOSE

This communication reports the long-term results of the original group of prostate cancer patients who participated in the first prospective Fox Chase Cancer Center radiation dose escalation study for which 8-12 years of follow-up is now available.

METHODS AND MATERIALS

Between March 1, 1989 and October 31, 1992, 232 patients with clinically localized prostate cancer received three-dimensional conformal radiotherapy only at Fox Chase Cancer Center in a prospective dose-escalation study. Of these patients, 229 were assessable. The 8-, 10-, and 12-year actuarial rates of biochemical control (biochemically no evidence of disease [bNED]), freedom from distant metastasis (FDM), and morbidity were calculated. The Cox proportional hazards model was used to assess multivariately the predictors of bNED control and FDM, including pretreatment prostate-specific antigen (PSA) level (continuous), tumor stage (T1/T2a vs. T2b/T3), Gleason score (2-6 vs. 7-10), and radiation dose (continuous). The median total dose for all patients was 74 Gy (range 67-81). The median follow-up for living patients was 110 months (range 89-147). bNED control was defined using the American Society for Therapeutic Radiology and Oncology consensus definition.

RESULTS

The actuarial bNED control for all patients included in this series was 55% at 5 years, 48% at 10 years, and 48% at 12 years. Patients with pretreatment PSA levels of 10-20 ng/mL had statistically significant differences (19% vs. 31% vs. 84%, p = 0.0003) in bNED control when stratified by dose (<71.5, 71.5-75.6, and > 75.6 Gy, respectively) on univariate analysis. For the 229 patients with follow-up, 124 (54%) were clinically and biochemically without evidence of disease. Sixty-nine patients were alive at the time of last follow-up, and 55 patients were dead of intercurrent disease. On multivariate analysis, radiation dose was a statistically significant predictor of bNED control for all patients and for unfavorable patients with a pretreatment PSA <10 ng/mL. For the patients with a pretreatment PSA level of 10-20 ng/mL, the radiation dose was a statistically significant predictor across all groups. No radiation dose response was seen for those patients with a pretreatment PSA level >20 ng/mL, although large numbers of patients are required to demonstrate a difference. The radiation dose, Gleason score, and palpation T stage were significant predictors for the entire patient set, as well as for those with pretreatment PSA levels between 10 and 20 ng/mL. The FDM rate for all patients included in this series was 89%, 83%, and 83% at 5, 10, and 12 years, respectively. For patients with pretreatment PSA levels <10 ng/mL, all four covariates (radiation dose, Gleason score, pretreatment PSA, and palpation T stage) were significant predictors of distance metastasis. Using the Radiation Therapy Oncology Group morbidity scale, no difference was noted in the frequency of Grade 2 and 3 genitourinary and Grade 3 gastrointestinal morbidity when patients in this data set were stratified by radiation dose. However, a significant increase occurred in Grade 2 gastrointestinal complications as the radiation dose increased.

CONCLUSION

The long-term results of the original Fox Chase radiation dose escalation study with >9 years of median follow-up confirm the existence of a dose response for both bNED control and FDM. The dose response in prostate cancer is real, and the absence of biochemical recurrence after 8 years demonstrates the lack of late failure and suggests cure.

Long-term durability of PSA failure-free survival after radiotherapy for localized prostate cancer

PURPOSE

To determine the durability of prostate-specific antigen (PSA) progression-free survival beyond 5 years in patients biochemically free of relapse 5 years after external beam radiotherapy (EBRT).

METHODS AND MATERIALS

This study identified 328 men treated with EBRT to the prostate who were biochemically (American Society for Therapeutic Radiology and Oncology definition) disease free 5 years after treatment. The median follow-up was 7.4 years. The patients were divided into four groups according to their PSA values 5 years after treatment: PSA <or=0.5, 0.5 to <or=1.0, 1.0 to <or=2.0, and 2.0-4.0 ng/mL. PSA progression-free rates were calculated in each subgroup at 10 years after treatment. Yearly hazard rates of biochemical progression were also calculated for the 5-10 years after treatment.

RESULTS

The PSA progression-free survival rate was 87%, 79%, and 67%, respectively, 8, 10, and 13 years after treatment in patients biochemically free of disease 5 years after treatment. The progression-free rates at 10 years after treatment according to the PSA level at 5 years was 92% for PSA <or=0.5 ng/mL; 71% for PSA 0.5 to <or=1.0 ng/mL; 78% for PSA 1.0 to <or=2.0 ng/mL; and 56% for PSA 2.0 to <or=4.0. The lower the PSA level at 5 years, the more durable the probability of maintained biochemical disease-free survival (p <0.0001). The yearly hazard rates of biochemical progression ranged from 3.1% to 6.6% in the 5-10 years after RT.

CONCLUSION

When PSA levels remain low (<2 ng/mL) 5 years after EBRT, the great majority of patients will be biochemically disease free at 10 years. The hazard rates of biochemical progression in the 6-10 years after treatment are low and are comparable to those published for prostatectomy series.

Pathologic evidence of dose-response and dose-volume relationships for prostate cancer treated with combined external beam radiotherapy and high-dose-rate brachytherapy

PURPOSE

The clinical significance of postradiotherapy (RT) prostate biopsy characteristics is not well understood relative to the known prognostic factors. We performed a detailed pathologic review of posttreatment biopsy specimens in an attempt to clarify their relationship with clinical outcome and radiation dose.

METHODS AND MATERIALS

Between 1991 and 1998, 78 patients with locally advanced prostate cancer were prospectively treated with external beam RT in combination with high-dose-rate brachytherapy at William Beaumont Hospital and had post-RT biopsy material available for a complete pathologic review. Patients with any of the following characteristics were eligible for study entry: pretreatment prostate-specific antigen level > or =10.0 ng/mL, Gleason score > or =7, or clinical Stage T2b-T3cN0M0. Pelvic external beam RT (46.0 Gy) was supplemented with three (1991-1995) or two (1995-1998) ultrasound-guided transperineal interstitial (192)Ir high-dose-rate implants. The brachytherapy dose was escalated from 5.50 to 10.50 Gy per implant. Post-RT prostate biopsies were performed per protocol at a median interval of 1.5 years after RT. All pre- and post-RT biopsy specimen slides from each case were reviewed by a single pathologist (N.S.G.). The presence and amount of residual cancer, most common RT-effect score, and least amount RT-effect score were analyzed. The median follow-up was 5.7 years. Biochemical failure was defined as three consecutive prostate-specific antigen rises.

RESULTS

Forty patients (51%) had residual cancer in the post-RT biopsies. The 7-year biochemical control rate was 79% for patients with negative biopsies vs. 62% for those with positive biopsies with marked RT damage vs. 33% for those with positive biopsies with no or minimal RT damage. A greater percentage of positive pre-RT biopsy cores (p = 0.01), lower total RT dose (p = 0.001), lower dose per implant (p = 0.001), and greater percentage of positive post-RT biopsy cores (p = 0.01) were each associated with biochemical failure (Cox regression, univariate analysis). For patients with <25% positive post-RT biopsy cores, the 7-year biochemical control rate was 81% vs. a 62% biochemical control rate for those with 25-49% positive cores and only 32% for those with > or =50% positive cores (p = 0.01). On Cox multiple regression analysis, only the percentage of positive pre-RT biopsy cores and RT dose remained significantly associated with biochemical failure. Of all the factors analyzed, only the pretreatment cancer volume and lower RT dose were significantly associated with residual cancer and/or residual cancer with no or minimal RT damage. A greater percentage of positive pre-RT biopsy cores was associated with both a positive post-RT biopsy (p = 0.08) and a greater percentage of positive post-RT biopsy cores (p = 0.04). A lower total RT dose was associated with both a positive post-RT biopsy (p = 0.08) and a greater percentage of positive post-RT biopsy cores (p = 0.02). For patients who received <80 Gy (equivalent in 2-Gy fractions), 73% had positive post-RT biopsies vs. a 56% biopsy positivity rate for those who received 84-90 Gy and only 39% for those who received > or =92 Gy (p = 0.07).

CONCLUSION

Patients with positive post-RT biopsies are more likely to experience biochemical failure, especially when the RT damage is minimal. Patients who have a larger pretreatment tumor volume or receive a lower RT dose are more likely to demonstrate post-RT biopsy positivity and biochemical failure.

The use of conformal radiotherapy and the selection of radiation dose in T1 or T2 low or intermediate risk prostate cancer – a systematic review

BACKGROUND AND PURPOSE

The purpose was to develop a systematic review that would address the following questions: (a) when single-modality treatment external-beam radiotherapy is selected as the modality of choice, what is the role of three-dimensional (3D) conformal radiotherapy in treating clinically localized (T1, T2/NO, NX/MO) prostate cancer? The outcomes of interest are biochemical freedom from failure (bNED) rates, clinical recurrence-free survival, disease-specific survival and acute and late toxicity; (b) what is the appropriate dose and fractionation prescription in this clinical setting?

MATERIALS AND METHODS

A systematic review of the English published literature was undertaken to provide evidence relevant to the above outcomes.

RESULTS

One randomized controlled trial comparing conventional radiotherapy to conformal therapy with dose escalation reported bNED rates. Three additional randomized controlled trials reported acute or chronic late outcome assessments. Additionally, phase II studies of dose escalation in sequential patient cohorts and non-randomized comparative assessments of dose-response and bNED rates in controlled analyses were reviewed. There is convincing evidence from randomized trials that the use of conformal therapy reduces acute and late treatment-related morbidity. There is preliminary evidence suggesting that when external-beam therapy alone is used to treat patients, conformal therapy with dose-escalation is more efficacious than doses of 70Gy. The increased efficacy appears to be predominantly seen in the subset of patients with intermediate-risk disease (PSA 10-20). There is conflicting evidence of the efficacy of dose-escalation in patients with low initial PSA (<10) and in patients with initial PSA greater than 20. Conformal radiotherapy at a dose of 78Gy appears to be relatively safe with no increase in acute or late effects compared with conventional treatment (up to 70Gy) so long as appropriate technological principles are considered.

CONCLUSIONS

Patients who have external-beam radiotherapy should be treated using a 3D conformal technique. Patients with intermediate-risk disease (PSA 10-20) who are treated with external-beam radiotherapy alone should be offered doses of 75-78Gy in 180-200cGy fractions.

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

PURPOSE

A randomized radiotherapy dose escalation trial was undertaken between 1993 and 1998 to compare the efficacy of 70 vs. 78 Gy in controlling prostate cancer.

METHODS AND MATERIALS

A total of 305 Stage T1-T3 patients were entered into the trial and, of these, 301 with a median follow-up of 60 months, were assessable. Of the 301 patients, 150 were in the 70 Gy arm and 151 were in the 78 Gy arm. The primary end point was freedom from failure (FFF), including biochemical failure, which was defined as 3 rises in the prostate-specific antigen (PSA) level. Kaplan-Meier survival analyses were calculated from the completion of radiotherapy. The log-rank test was used to compare the groups. Cox proportional hazard regression analysis was used to examine the independence of study randomization in multivariate analysis.

RESULTS

There was an even distribution of patients by randomization arm and stage, Gleason score, and pretreatment PSA level. The FFF rates for the 70- and 78 Gy arms at 6 years were 64% and 70%, respectively (p = 0.03). Dose escalation to 78 Gy preferentially benefited those with a pretreatment PSA >10 ng/mL; the FFF rate was 62% for the 78 Gy arm vs. 43% for those who received 70 Gy (p = 0.01). For patients with a pretreatment PSA <or=10 ng/mL, no significant dose response was found, with an average 6-year FFF rate of about 75%. Although no difference occurred in overall survival, the freedom from distant metastasis rate was higher for those with PSA levels >10 ng/mL who were treated to 78 Gy (98% vs. 88% at 6 years, p = 0.056). Rectal side effects were also significantly greater in the 78 Gy group. Grade 2 or higher toxicity rates at 6 years were 12% and 26% for the 70 Gy and 78 Gy arms, respectively (p = 0.001). Grade 2 or higher bladder complications were similar at 10%. For patients in the 78 Gy arm, Grade 2 or higher rectal toxicity correlated highly with the proportion of the rectum treated to >70 Gy.

CONCLUSION

An increase of 8 Gy resulted in a highly significant improvement in FFF for patients at intermediate-to-high risk, although the rectal reactions were also increased. Dose escalation techniques that limit the rectal volume that receives >or=70 Gy to <25% should be used.