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

The Clinical Application of Intensity-Modulated Radiation Therapy

Intensity-modulated radiation therapy is a delivery system that, when coupled with a treatment-planning optimization system, presents the opportunity to conform the dose to the target better than 3-dimensional conformal therapy, particularly in the case of concave targets. Appropriate clinical applications of this technology to challenging patient treatment scenarios requires careful consideration of issues related to target volume-dose heterogeneity and the influence of patient setup uncertainties. These issues are reviewed and illustrated. To date, clinical reports of these treatments for prostate and head and neck cancers have the most mature data. Those results are summarized here. Future applications of this technology can be expected to take careful, considered advantage of this technology to further rearrange dose distributions across target volumes to produce an integrated overall gain in treatment objectives. However, these innovative applications need to be approached with caution, preferably in prospective clinical trials that would help determine if the hypothetical clinical benefits are in fact realizable.

Image-guided radiotherapy: rationale, benefits, and limitations

Technological advances have greatly enhanced the specialty of radiation oncology by allowing more healthy tissue to be spared for the same or better tumour coverage. Developments in medical imaging are integral to radiation oncology, both for design of treatment plans and to localise the target for precise administration of radiation. At planning, definition of the tumour and healthy tissue is based on CT, augmented frequently with MRI and PET. At treatment, three-dimensional soft-tissue imaging can also be used to localise the target and tumour motion can be tracked with fluoroscopic imaging of radio-opaque markers implanted in or near the tumour. These developments allow changes in tumour position, size, and shape that take place during radiotherapy to be measured and accounted for to boost geometric accuracy and precision of radiation delivery. Image-guided treatment also enhances uniformity in doses administered in a population of patients, thus improving our ability to measure the effect of dosimetric and non-dosimetric factors on tumour and healthy tissue outcomes in clinical trials. Increased precision and accuracy of radiotherapy are expected to augment tumour control, reduce incidence and severity of toxic effects after radiotherapy, and facilitate development of more efficient shorter schedules than currently available.

Carbon ion radiation therapy for prostate cancer: results of a prospective phase II study

BACKGROUND AND PURPOSE

To determine the efficacy and feasibility of carbon ion radiotherapy (C-ion RT) for prostate cancer.

PATIENTS AND METHODS

Between April 2000 and November 2003, 175 patients received C-ion RT using a recommended dose fractionation (66.0 GyE/20 fractions) established from prior studies. C-ion RT alone was performed for 33 patients constituting a low-risk group (Stage < or =T2a and PSA <20 ng/ml and Gleason score < or =6); the remaining 142 high-risk patients received an additional androgen deprivation therapy (ADT).

RESULTS

The 4-year overall survival and bNED rates were 91% and 87%, respectively. Local control was achieved in all but one patient. The 4-year bNED rates were 87% in the low-risk group and 88% in the high-risk group. In very advanced diseases (Stage > or= T3a or PSA > or= 20 ng/ml or Gleason score > or =8), there was significant difference in the bNED rate according to period of ADT administration (ADT > or =24 months: 93%, ADT <24 months: 73%, p<0.01). Grade 2 late toxicities developed in 4 patients (2%) for the rectum and 9 patients (5%) for the genitourinary system but no Grade 3 or higher toxicity was observed.

CONCLUSIONS

The effectiveness of C-ion RT for prostate cancer has been well confirmed. Based on these results, new study of a C-ion RT modified for the administration strategy of ADT according to the patient risk has been started by dividing patients into 3 groups, high-risk, intermediate-risk, and low-risk.

Emptying the rectum before treatment delivery limits the variations of rectal dose - volume parameters during 3DCRT of prostate cancer

PURPOSE

To investigate the impact of rectum motion on dose - volume histograms of the rectum including filling and of the wall (DVH and DWH, respectively), during 3D-conformal radiotherapy (3DCRT) for localized prostate cancer.

MATERIALS AND METHODS

Ten patients received a planning CT scan (CT(0)) and 11-14 CT during 3DCRT for prostate cancer (total CT scans=126). CT images were 3D matched using bony anatomy. A single observer drew the external contours of rectum and rectum wall and the CTV (prostate + seminal vesicles) on CT(0). Patients were asked to empty their rectum before every CT, as generally performed at the Institute for Cancer Research and Treatment (IRCC) before treatment delivery. Bladder was kept full by drinking 500 cm(3) of water 60 min before the scan, according to our protocol. A 4-field box 3DCRT technique was planned and dose statistics/dose - volume histograms of the rectum were calculated for each contour referred to CT(0),CT(1),...,CT(n) for each patient. Average DVHs during treatment were calculated along with their standard deviation (SD(rand)) and compared to the planned DVH. The analyses on the patient population included the assessment of systematic deviation (average difference and SD, named SD(sys)) as well as the average SD(rand) value expressing the random component of organ motion. Rectum shifts were also assessed by anterior and lateral BEV projections.

RESULTS

As to the rectum, 8/10 patients showed a "better" average DVH than DVH on CT(0). Wilcoxon test showed a statistically significant reduction when correlating the difference Delta between the average DVH during therapy and planning DVH at CT(0): for instance V(70)Delta = -3.6% and p = 0.022, V(50)Delta = -5.5% and p = 0.022, D(med)Delta = -3.2 Gy and p = 0.007. Average values of DVH systematic difference (average difference between planning scan and treatment), standard deviations (SD(sys)) and average standard deviations of the random fluctuation (SD(random)) were -4.0%, 4.7% and 6.6%, respectively. Whilst the fluctuation results were slightly smaller for DWH. Volume analysis showed a slight systematic variation of the rectal volume between planning and treatment BEV. The average rectal volume during therapy was larger than at the planning CT in 8/10 patients. The systematic shifts of the rectal wall between the planning phase and the treatment were rather small, both below and above the flexure. The larger random fluctuation of the rectum shape was found to be in the cranial half (1 SD=4.4 mm).

CONCLUSIONS

The practice of carefully emptying the rectum during simulation and therapy for prostate cancer, which is a safe and simple procedure, reduces the impact of organ motion on dose - volume parameters of the rectum.

Distinct effects of rectum delineation methods in 3D-conformal vs. IMRT treatment planning of prostate cancer

Background

The dose distribution to the rectum, delineated as solid organ, rectal wall and rectal surface, in 3D conformal (3D-CRT) and intensity-modulated radiotherapy treatment (IMRT) planning for localized prostate cancer was evaluated.

Materials and methods

In a retrospective planning study 3-field, 4-field and IMRT treatment plans were analyzed for ten patients with localized prostate cancer. The dose to the rectum was evaluated based on dose-volume histograms of 1) the entire rectal volume (DVH) 2) manually delineated rectal wall (DWH) 3) rectal wall with 3 mm wall thickness (DWH₃) 4) and the rectal surface (DSH). The influence of the rectal filling and of the seminal vesicles' anatomy on these dose parameters was investigated. A literature review of the dose-volume relationship for late rectal toxicity was conducted.

Results

In 3D-CRT (3-field and 4-field) the dose parameters differed most in the mid-dose region: the DWH showed significantly lower doses to the rectum (8.7% ± 4.2%) compared to the DWH₃ and the DSH. In IMRT the differences between dose parameters were larger in comparison with 3D-CRT. Differences were statistically significant between DVH and all other dose parameters and between DWH and DSH. Mean doses were increased by 23.6% ± 8.7% in the DSH compared to the DVH in the mid-dose region. Furthermore, both the rectal filling and the anatomy of the seminal vesicles influenced the relationship between the dose parameters: a significant correlation of the difference between DVH and DWH and the rectal volume was seen in IMRT treatment.

Discussion

The method of delineating the rectum significantly influenced the dose representation in the dose-volume histogram. This effect was pronounced in IMRT treatment planning compared to 3D-CRT. For integration of dose-volume parameters from the literature into clinical practice these results have to be considered.

Setup accuracy of stereoscopic X-ray positioning with automated correction for rotational errors in patients treated with conformal arc radiotherapy for prostate cancer

We evaluated setup accuracy of NovalisBody stereoscopic X-ray positioning with automated correction for rotational errors with the Robotics Tilt Module in patients treated with conformal arc radiotherapy for prostate cancer. The correction of rotational errors was shown to reduce random and systematic errors in all directions. (NovalisBody and Robotics Tilt Module are products of BrainLAB A.G., Heimstetten, Germany).

A theoretical approach to the problem of dose-volume constraint estimation and their impact on the dose-volume histogram selection

This paper outlines a theoretical approach to the problem of estimating and choosing dose-volume constraints. Following this approach, a method of choosing dose-volume constraints based on biological criteria is proposed. This method is called "reverse normal tissue complication probability (NTCP) mapping into dose-volume space" and may be used as a general guidance to the problem of dose-volume constraint estimation. Dose-volume histograms (DVHs) are randomly simulated, and those resulting in clinically acceptable levels of complication, such as NTCP of 5 +/- 0.5%, are selected and averaged producing a mean DVH that is proven to result in the same level of NTCP. The points from the averaged DVH are proposed to serve as physical dose-volume constraints. The population-based critical volume and Lyman NTCP models with parameter sets taken from literature sources were used for the NTCP estimation. The impact of the prescribed value of the maximum dose to the organ, D(max), on the averaged DVH and the dose-volume constraint points is investigated. Constraint points for 16 organs are calculated. The impact of the number of constraints to be fulfilled based on the likelihood that a DVH satisfying them will result in an acceptable NTCP is also investigated. It is theoretically proven that the radiation treatment optimization based on physical objective functions can sufficiently well restrict the dose to the organs at risk, resulting in sufficiently low NTCP values through the employment of several appropriate dose-volume constraints. At the same time, the pure physical approach to optimization is self-restrictive due to the preassignment of acceptable NTCP levels thus excluding possible better solutions to the problem.

[High precision radiotherapy with ultrasonic imaging guidance]

Conformal radiation therapy with or without intensity modulation is the standard treatment of localized prostate cancer and facilitates dose escalation. The implementation of three-dimensional conformal radiotherapy necessitates focusing on target volume delineation, dosimetry, reproducibility of treatment and quality control. Recently, ultrasound systems that allow direct daily visualization of the prostate have become available. This non-invasive technique can be used to correct both prostate organ motion and set-up error and leads to increase treatment accuracy.

High Dose Rate Iridium-192 Brachytherapy as a Component of Radical Radiotherapy for the Treatment of Localised Prostate Cancer

AIMS

To assess the treatment outcomes and toxicity of conformal high dose rate (HDR) brachytherapy boost as a means of radiation dose escalation in patients with localised prostate cancer.

MATERIALS AND METHODS

Between December 1998 and July 2004, 65 consecutive patients with localised prostate cancer (magnetic resonance imaging-staged T1-3 N0 M0) were treated with external beam radiation therapy (EBRT) followed by two fractions of HDR iridium-192 brachytherapy. The patients selected this treatment modality in preference to entering an ongoing randomised phase 3 trial. Any pre-treatment serum prostate-specific antigen (PSA) and Gleason score were included. The primary end point was biochemical disease-free progression. Late treatment-related morbidity was graded according to the Radiation Therapy Oncology Group and the European Organization for Research and Treatment of Cancer criteria.

RESULTS

The median patient age was 67.3 years (range 47.9-80). Sixty patients (92.3%) had intermediate- to high-risk disease defined by clinical stage, presenting PSA and Gleason score/World Health Organisation (WHO) grade. With a median follow-up of 3.5 years (range 0.6-5.8), two patients had died of metastatic disease and another four patients had PSA relapse, giving a 3-year actuarial biochemical disease-free progression of 90.8%. Three patients (4.6%) had acute grade 3 genitourinary toxicity, in the form of urinary retention. Late grade 3 and 4 genitourinary toxicities occurred in four patients (6.2%) and one patient (1.5%), respectively. No late gastrointestinal toxicities were observed.

CONCLUSIONS

These results suggest that the combined modality of conformal HDR brachytherapy and EBRT is a feasible treatment modality with acceptable acute and late toxicities, comparable with those of EBRT alone. It offers an attractive conformal treatment modality with the potential of further dose escalation in the treatment of localised prostate cancer.

Update on Radiation Therapy in Prostate Cancer

Higher doses of radiation result in improved clinical control of prostate cancer,and the recent advances in prostate cancer radiotherapy are designed to escalate dose while minimizing toxicity. To achieve this goal, tighter treatment margins are needed, which require more accurate delineation of the prostate target and normal tissue at the time of treatment planning and before actual daily treatments. Modem radiation therapy techniques can deposit conformal dose virtually anywhere in the body; however, this precise therapy is of no value if it is not accurately hitting the target. Whether dose escalation is achieved by external beam techniques (eg, IMRT, protons) or brachytherapy, these ba-sic planning and delivery considerations are essentially the same. Future directions in prostate radiation therapy will use even higher radiation doses,alternative fractionation patterns, intraprostatic targets (eg, prostate tumor seen on MRI), and improved patient selection regarding which patients will benefit the most from these advanced techniques.

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.

Salvage conformal radiotherapy for biochemical recurrent prostate cancer after radical prostatectomy

OBJECTIVE

Assess the results of salvage conformal radiotherapy in patients with biochemical failure after radical prostatectomy and identify prognostic factors for biochemical recurrence and toxicity of the treatment.

MATERIALS AND METHODS

From June 1998 to November 2001, 35 patients were submitted to conformal radiotherapy for PSA > or = 0.2 ng/mL in progression after radical prostatectomy and were retrospectively analyzed. The mean dose of radiation in prostatic bed was of 77.4 Gy (68-81). Variables related to the treatment and to tumor were assessed to identify prognostic factors for biochemical recurrence after salvage radiotherapy.

RESULTS

The median follow-up was of 55 months (17-83). The actuarial survival rates free of biochemical recurrence and free of metastasis at a distance of 5 years were 79.7% e 84.7%, respectively. The actuarial global survival rate in 5 years was 96.1%. The actuarial survival rate free of biochemical recurrence in 5 years was 83.3% with PSA pre-radiotherapy < or = 1, 100% when > 1 and < or = 2, and 57.1% when > 2 (p = 0.023). Dose > 70 Gy in 30% of the bladder volume implied in more acute urinary toxicity (p = 0.035). The mean time for the development of late urinary toxicity was 21 months (12-51). Dose > 55 Gy in 50%bladder volume implied in more late urinary toxicity (p = 0.018). A patient presented late rectal toxicity of 2nd grade.

CONCLUSIONS

Conformal radiotherapy showed to be effective for the control of biochemical recurrence after radical prostatectomy. Patients with pre-therapy PSA < or = 2 ng/mL have more biochemical control.

Intrarectal amifostine suspension may protect against acute proctitis during radiation therapy for prostate cancer: a pilot study

PURPOSE

Our goal was to test the ability of intrarectal amifostine to limit symptoms of radiation proctitis.

METHODS AND MATERIALS

The first 18 patients received 1 g of intrarectal amifostine suspension placed 30-45 min before each radiation treatment. The following 12 patients received 2 g of amifostine. Total dose prescribed ranged from 66 to 76 Gy. All patients were treated with three-dimensional conformal radiation therapy. The suspension remained intrarectal during treatment and was expelled after treatment. For gastrointestinal symptoms, during treatment and follow-up, all patients had a Radiation Therapy Oncology Group (RTOG) grade recorded.

RESULTS

Median follow-up was 18 months (range, 6-24 months). With 2 g vs. 1 g amifostine, there was a nearly significant decrease in RTOG Grade 2 acute rectal toxicity. Seven weeks after the start of radiation therapy, the incidence of Grade 2 toxicity was 33% in the 1-g group (6/18) compared with 0% (0/12) in the 2-g group (p=0.06). No Grade 3 toxicity or greater occurred in this study.

CONCLUSION

This trial suggests greater rectal radioprotection from acute effects with 2 g vs. 1 g amifostine suspension. Further studies should be conducted in populations at higher risk for developing symptomatic acute and late proctitis.

Treatment planning and dosimetry of a multi-axis dynamic arc technique for prostate cancer: A comparison with IMRT

PURPOSE

Intensity-modulated radiation therapy (IMRT) allows greater dose conformity to the tumor target. However, IMRT, especially static delivery, usually requires more time to deliver a dose fraction than conventional external beam radiotherapy (EBRT). The authors have been using a "two-axis dynamic arc therapy" (2A-DAT) technique for prostate cancer treatment to make a concave dose distribution to spare the rectum and bladder while working with limited time and human resources. The objectives of this study were to (1) clinically implement the 2A-DAT technique, (2) evaluate the dosimetry in comparison with IMRT, and (3) analyze the initial treatment outcome.

MATERIALS AND METHODS

The 2A-DAT consists of two dynamic arc therapies (DATs) with half rotation around two isocenters each in two separate symmetrical rhombi. Treatment planning is forward and on a trial-and-error basis. Thirty-four patients received 2A-DAT with a median prescribed dose of 70 Gy.

RESULTS

Although inferior in dose uniformity, the 2A-DAT provided equivalent sparing of normal structures to IMRT. Daily fraction delivery time for the 34 patients ranged from 6.4 to 9.6 minutes, with an average of 7.4 minutes. Five-year survival and five-year prostate specific autigen (PSA) failure-free survival were 89.3% and 79.5%, respectively. Three patients developed grade 2 proctitis.

CONCLUSION

This technique is a possible alternative to IMRT in EBRT of prostate cancer.

Challenge of dose escalation in locally advanced unfavourable prostate cancer using HDR brachytherapy

In men with locally advanced/high-risk prostate cancer, there is an ongoing challenge to achieve improved results. Dose escalation studies using three-dimensional conformal radiotherapy (3D-CRT) or intensity modulated radiation therapy (IMRT) have shown benefit particularly in the intermediate and poor risk groups of patients. Of concern, however, is the increase in documented rectal toxicity. High-dose rate brachytherapy (HDR-BT) as a boost in combination with external beam radiotherapy (EBRT) is an alternative strategy of dose escalation that can potentially achieve an even higher biological equivalent dose (BED) to the tumour. The results so far are very encouraging for men with poor prognosis disease. Moreover the technique is associated with very low rates of acute and late toxicity.

Phase II study of a four-week hypofractionated external beam radiotherapy regimen for prostate cancer: Report on acute toxicity

PURPOSE

To evaluate the early side effects of a short course hypofractionated radiotherapy regimen in prostate cancer.

MATERIALS AND METHODS

Three institutions (IRE, AZ VUB, GUH) included 36 patients with T1-T3N0M0 prostate cancer in a phase II study. Patients were treated with 56 Gy in 16 fractions over 4 weeks. Early side effects were scored using the RTOG/EORTC criteria and the international prostate symptom index (IPSI) weekly during treatment and 1 and 2 months afterwards. The results were compared with two control groups of patients previously treated with conventional fractionation at AZ VUB (238 patients) and GUH (114 patients).

RESULTS

None of the patients experienced grade 3-4 toxicity. Grade 1-2 Gastro-intestinal (GI), grade 2 GI, grade 1-2 Genito-urinary (GU) and grade 2 GU toxicity occurred in 75%, 36%, 75% and 44% for the hypofractionation schedule. The corresponding figures were 25-44%, 6-29%, 47-53% and 16-44% for the control groups (p<0.01 for grade 1-2 GI and GU toxicity). Two months after treatment all GU and the majority of GI symptoms had resolved. The IPSI increased from (average +/-1 SD) 5.6+/-4 pre-treatment to 10.0+/-6 during week 2-4 and had normalized (5.2+/-4) two months after treatment.

CONCLUSIONS

Though no grade 3-4 side effects were observed, the investigated schedule results in a marked increase of grade 1-2 early side effects as compared to a conventional regimen. Side effects resolved within two months post-treatment.

Minimal displacement of novel self-anchoring catheters suitable for temporary prostate implants

Catheters were developed that can be fixed in the prostate gland by self-expanding parts for use in PDR brachytherapy. Daily CT-scans were made to investigate the magnitude of catheter displacement. The mean absolute displacement during the 3 day treatment was 1.2 mm. The resulting minor alterations in dose-volume parameters were of no clinical importance.

A comparison of CT- and ultrasound-based imaging to localize the prostate for external beam radiotherapy

PURPOSE

This study assesses the accuracy of NOMOS B-mode acquisition and targeting system (BAT) compared with computed tomography (CT) in localizing the prostate.

METHODS AND MATERIALS

Twenty-six patients were CT scanned, and the prostate was localized by 3 observers using the BAT system. The BAT couch shift measurements were compared with the CT localization. Six of the patients had gold markers present in the prostate, and the prostate movement determined by BAT was compared with the movement determined by the gold markers.

RESULTS

Using the BAT system, the 3 observers determined the prostate position to be a mean of 1-5 mm over all directions with respect to the CT. The proportion of readings with a difference >3 mm between the observers was in the range of 25% to 44%. The prostate movement based on gold markers was an average of 3-5 mm different from that measured by BAT. The literature assessing the accuracy and reproducibility on BAT is summarized and compared with our findings.

CONCLUSIONS

We have found that there are systematic differences between the BAT-defined prostate position compared with that estimated on CT using gold grain marker seeds.

Clinicopathologic analysis of extracapsular extension in prostate cancer: Should the clinical target volume be expanded posterolaterally to account for microscopic extension?

PURPOSE

We performed a complete pathologic analysis examining extracapsular extension (ECE) and microscopic spread of malignant cells beyond the prostate capsule to determine whether and when clinical target volume (CTV) expansion should be performed.

METHODS AND MATERIALS

A detailed pathologic analysis was performed for 371 prostatectomy specimens. All slides from each case were reviewed by a single pathologist (N.S.G.). The ECE status and ECE distance, defined as the maximal linear radial distance of malignant cells beyond the capsule, were recorded.

RESULTS

A total of 121 patients (33%) were found to have ECE (68 unilateral, 53 bilateral). Median ECE distance=2.4 mm [range: 0.05-7.0 mm]. The 90th-percentile distance = 5.0 mm. Of the 121 cases with ECE, 55% had ECE distance>or=2 mm, 19%>or=4 mm, and 6%>or=6 mm. ECE occurred primarily posterolaterally along the neurovascular bundle in all cases. Pretreatment prostrate-specific antigen (PSA), biopsy Gleason, pathologic Gleason, clinical stage, bilateral involvement, positive margins, percentage of gland involved, and maximal tumor dimension were associated with presence of ECE. Both PSA and Gleason score were associated with ECE distance. In all 371 patients, for those with either pretreatment PSA>or=10 or biopsy Gleason score>or=7, 21% had ECE>or=2 mm and 5%>or=4 mm beyond the capsule. For patients with both of these risk factors, 49% had ECE>or=2 mm and 21%>or=4 mm.

CONCLUSIONS

For prostate cancer with ECE, the median linear distance of ECE was 2.4 mm and occurred primarily posterolaterally. Although only 5% of patients demonstrate ECE>4 to 5 mm beyond the capsule, this risk may exceed 20% in patients with PSA>or=10 ng/ml and biopsy Gleason score>or=7. As imaging techniques improve for prostate capsule delineation and as radiotherapy delivery techniques increase in accuracy, a posterolateral CTV expansion should be considered for patients at high risk.

Outcome analysis of 300 prostate cancer patients treated with neoadjuvant androgen deprivation and hypofractionated radiotherapy

PURPOSE

Neoadjuvant androgen deprivation and radical radiotherapy is an established treatment for localized prostate carcinoma. This study sought to analyze the outcomes of patients treated with relatively low-dose hypofractionated radiotherapy.

METHODS AND MATERIALS

Three hundred patients with T1-T3 prostate cancer were treated between 1996 and 2001. Patients were prescribed 3 months of neoadjuvant androgen deprivation before receiving 5250 cGy in 20 fractions. Patients' case notes and the oncology database were used to retrospectively assess outcomes. Median follow-up was 58 months.

RESULTS

Patients presented with prostate cancer with poorer prognostic indicators than that reported in other series. At 5 years, the actuarial cause-specific survival rate was 83.2% and the prostate-specific antigen (PSA) relapse rate was 57.3%. Metastatic disease had developed in 23.4% of patients. PSA relapse continued to occur 5 years from treatment in all prognostic groups. Independent prognostic factors for relapse included treatment near the start of the study period, neoadjuvant oral anti-androgen monotherapy rather than neoadjuvant luteinizing hormone releasing hormone therapy, and diagnosis through transurethral resection of the prostate rather than transrectal ultrasound.

CONCLUSION

This is the largest reported series of patients treated with neoadjuvant androgen deprivation and hypofractionated radiotherapy in the United Kingdom. Neoadjuvant hormonal therapy did not appear to adequately compensate for the relatively low effective radiation dose used.

[High-dose rate brachytherapy for high-risk prostate cancer]

To estimate disease-free survival it is necessary to allocate patients into tumor risk groups: locally advanced prostate carcinoma with extracapsular spread or localized prostate carcinoma of tumor stage T2c or one of the risk factors PSA >20 or Gleason > or =8 apply for the high-risk group. Intermediate-risk carcinomas are those belonging to tumor stage T2b or with PSA >10-20 or Gleason 7. Particularly for patients with intermediate and high-risk disease early PSA relapse is of major interest. This phenomenon could be a consequence of current inadequate imaging of lymph node or bone metastasis or as a consequence subclinical metastatic spread remains undetectable during radical treatment. However, tumor biology itself could lead to the progression of the disease in the high-risk group. As a consequence, risk-adapted therapy is very important in these cases. The applied radiation dose plays an important role in radiotherapy. Several publications have shown that the biochemical relapse correlates with the generally accepted risk factors and the radiation dose. Regarding this, high-quality treatment planning and HDR brachytherapy combined with EBRT (external beam radiation therapy) leads to good treatment results in selected groups. So far in our own experience, HDR brachytherapy in combination with EBRT is a successful form of treatment with few acute and late side effects in the first 42 patients examined. First results concerning to PSA relapse-free time, quality of life, miction, and erectile function are promising.

High-dose radiation employing external beam radiotherapy and high-dose rate brachytherapy with and without neoadjuvant androgen deprivation for prostate cancer patients with intermediate- and high-risk features

The role of neoadjuvant androgen deprivation (NAD) in high-risk prostate cancer patients receiving high-dose radiotherapy (RT) remains unstudied. To evaluate the effect of a course of NAD, we reviewed the experiences of three institutions treating these patients with combined RT and high-dose rate brachytherapy (HDR). Of 1260 prostate cancer patients with high-risk features (pretreatment prostate-specific antigen (PSA) > or =10, Gleason Score (GS) > or =7, or T stage > or =T2b), 560 received no NAD (n=308) or NAD for < or =6 months (n=252). Median dose to the prostate from RT and HDR was 42 and 23 Gy, respectively. Average total biologic equivalent prostate dose was >100 Gy (alpha/beta=1.2). Median follow-up was 4.3 years. Pretreatment characteristics were similar on chi(2) tables for all 560 patients treated with or without NAD including pretreatment PSA (P=0.11), GS (P=0.4), and clinical T stage (P=0.2). Outcomes worsened for patients receiving NAD (5-year distant metastasis (DM) 10 vs 5% (P=0.04); cause-specific survival (CSS), 93 vs 98% (P=0.005)). Higher 5-year DM rates and lower CSS occurred in NAD patients with a GS between 8 and 10 (n=112 (P=0.03, P=0.02)), pretreatment PSA> or =15 (n=136 (P=0.03, P=0.008)), and palpable disease > or =T2a (n=434 (P=0.04, P=0.02)). The only two significant risk factors for DM on Cox multivariate analysis were GS (P=0.003, HR 2.8) and NAD (P=0.03, HR 2.7). AD given before definitive high-dose RT did not benefit prostate cancer patients with intermediate- and high-risk features. We favor the use of concurrent/adjuvant AD over prolonged NAD for prostate cancer patients for whom AD is clinically indicated.

Variability of bladder filling in patients receiving radical radiotherapy to the prostate

BACKGROUND AND PURPOSE

Patients receiving radical radiotherapy to the prostate are requested to maintain a full bladder to displace the dome of the bladder and small bowel from the target volume. This study investigated patients' ability to consistently maintain a full bladder throughout planning and treatment before (Study 1) and after (Study 2) the introduction of a patient information sheet.

PATIENTS AND METHODS

Bladder volumes were measured on 41 patients at CT scanning, simulation and once weekly during treatment using a portable ultrasound device, BladderScan BVI 3000. Patients were asked their assessment of bladder fullness, time since last urination and the volume of fluid drank. A patient information sheet on bladder filling was then introduced and the study repeated on 25 patients (Study 2). The ultrasound bladder volumes measured at CT were compared to the CT scan data.

RESULTS

There was a strong correlation between the ultrasound and CT bladder volumes r = 0.88 (P < 0.01). There was a significant decrease between the volume at CT (mean 362 ml, SD 229 ml) and treatment (mean 251 ml, SD 171 ml) in Study 1 (P = 0.002). In Study 2 the mean volume at CT was 286 ml (SD 164 ml) compared to a mean of 312 ml (SD 196 ml) during treatment. The measured volume correlated with patient self-assessment (r = 0.47, P < 0.01). The median volume drank by patients in Study 2 was 350 ml (range 50-825 ml) compared to 450 ml (range 75-1500 ml) in Study 1.

CONCLUSIONS

Our initial results showed patients were unable to maintain a constant bladder volume during planning and treatment. Implementation of written bladder filling instructions was shown to improve bladder volume consistency.

Increasing external beam dose for T1-T2 prostate cancer: effect on risk groups

PURPOSE

The aim of this study was to investigate effect of increasing dose on risk groups for clinical failure (CF: local failure or distant failure or hormone ablation or PSA>or=25 ng/ml) in patients with T1-T2 prostate cancer treated with external beam radiotherapy.

METHODS AND MATERIALS

Patients (n=4,537) were partitioned into nonoverlapping dose ranges, each narrow enough that dose was not a predictor of CF, and risk groups for CF were determined using recursive partitioning analysis (RPA). The same technique was applied to the highest of these dose ranges (70-76 Gy, 1,136 patients) to compare risk groups for CF in this dose range with the conventional risk-group classification.

RESULTS

Cutpoints defining low-risk groups in each dose range shifted to higher initial PSA levels and Gleason scores with increasing dose. Risk groups for CF in the dose range 70-76 Gy were not consistent with conventional risk groups.

CONCLUSIONS

The conventional classification of risk groups was derived in the early PSA era, when total doses<70 Gy were common, and it is inconsistent with risk groups for patients treated to doses>70 Gy. Risk-group classifications must be continuously re-examined whenever the trend is toward increasing total dose.

Bladder filling variation during radiation treatment of prostate cancer: Can the use of a bladder ultrasound scanner and biofeedback optimize bladder filling?

PURPOSE

To investigate the use of a bladder ultrasound scanner in achieving a better reproducible bladder filling during irradiation of pelvic tumors, specifically prostate cancer.

METHODS AND MATERIALS

First, the accuracy of the bladder ultrasound scanner relative to computed tomography was validated in a group of 26 patients. Next, daily bladder volume variation was evaluated in a group of 18 patients. Another 16 patients participated in a biofeedback protocol, aiming at a more constant bladder volume. The last objective was to study correlations between prostate motion and bladder filling, by using electronic portal imaging device data on implanted gold markers.

RESULTS

A strong correlation between bladder scanner volume and computed tomography volume (r = 0.95) was found. Daily bladder volume variation was very high (1 SD = 47.2%). Bladder filling and daily variation did not significantly differ between the control and the feedback group (47.2% and 40.1%, respectively). Furthermore, no linear correlations between bladder volume variation and prostate motion were found.

CONCLUSIONS

This study shows large variations in daily bladder volume. The use of a biofeedback protocol yields little reduction in bladder volume variation. Even so, the bladder scanner is an easy to use and accurate tool to register these variations.

192Ir low dose rate brachytherapy for boosting locally advanced prostate cancers after external beam radiotherapy: A phase II trial

BACKGROUND AND PURPOSE

To evaluate on 201 locally advanced prostatic cancers prospectively treated in a phase II trial, the efficacy of a combination of external beam radiotherapy (39.6 Gy) and (192)Ir low dose rate brachytherapy (Bt) (40-45 Gy).

PATIENTS AND METHODS

Sixty-four patients were included in the intermediate prognosis group with only one of the following adverse factors (PSA > 10 ng/ml, Gleason score > or = 7 or clinical stage > or =T2b) and 137 in the unfavourable group when at least two of these factors were present.

RESULTS

The actuarial 4 years biochemical no evidence of disease is 82.8% for the entire population. It is, respectively, 97 and 76% in the intermediate and unfavourable prognosis groups (P < 0.0001). Grade > or =3 late urinary complications occurred in 13 patients (6.5%). Eight patients (4%) presented late grade 2 rectal complications but no grades 3-5 was observed.

CONCLUSIONS

Even if an alpha/beta of 1.5-3 Gy theoretically favours the use of a high dose rate mode of irradiation, the early results presented here are as good as those reported for similar groups of patients with high dose rate treatments. Late toxicity is identical but our urinary toxicity is within the less favourable and rectal toxicity within the most favourable results. We can postulate that while inducing very high hyperdosage regions (V150) mainly focused on the peripheral zone, most of the Bt techniques consist of a more ablative treatment. Many of the radiobiological studies on Bt did not in fact take into account the heterogeneity of irradiation inside the CTV. This study highlights the need to explore pulsed dose rate therapies, permanent implant and new available radioisotopes such as (169)Ytterbium that will offer the safety of low and lower dose rates. The actual late toxicity of the different Bt techniques is not yet inexistent indeed.

Rectal bleeding after high-dose-rate brachytherapy combined with hypofractionated external-beam radiotherapy for localized prostate cancer: Impact of rectal dose in high-dose-rate brachytherapy on occurrence of grade 2 or worse rectal bleeding

PURPOSE

To evaluate the incidence of Grade 2 or worse rectal bleeding after high-dose-rate (HDR) brachytherapy combined with hypofractionated external-beam radiotherapy (EBRT), with special emphasis on the relationship between the incidence of rectal bleeding and the rectal dose from HDR brachytherapy.

METHODS AND MATERIALS

The records of 100 patients who were treated by HDR brachytherapy combined with EBRT for > or =12 months were analyzed. The fractionation schema for HDR brachytherapy was prospectively changed, and the total radiation dose for EBRT was fixed at 51 Gy. The distribution of the fractionation schema used in the patients was as follows: 5 Gy x 5 in 13 patients; 7 Gy x 3 in 19 patients; and 9 Gy x 2 in 68 patients.

RESULTS

Ten patients (10%) developed Grade 2 or worse rectal bleeding. Regarding the correlation with dosimetric factors, no significant differences were found in the average percentage of the entire rectal volume receiving 30%, 50%, 80%, and 90% of the prescribed radiation dose from EBRT between those with bleeding and those without. The average percentage of the entire rectal volume receiving 10%, 30%, 50%, 80%, and 90% of the prescribed radiation dose from HDR brachytherapy in those who developed rectal bleeding was 77.9%, 28.6%, 9.0%, 1.5%, and 0.3%, respectively, and was 69.2%, 22.2%, 6.6%, 0.9%, and 0.4%, respectively, in those without bleeding. The differences in the percentages of the entire rectal volume receiving 10%, 30%, and 50% between those with and without bleeding were statistically significant.

CONCLUSIONS

The rectal dose from HDR brachytherapy for patients with prostate cancer may have a significant impact on the incidence of Grade 2 or worse rectal bleeding.

Radiotherapy in the management of common genitourinary malignancies

A continued role for radiation therapy in the multidisciplinary management of genitourinary malignancies seems certain. Treatment outcomes continue to improve, accompanied by diminishing rates of toxicity. With continued technologic advances in the delivery of radiation, including the use of adaptive radiotherapy, the discovery and application of novel treatment agents, and the combined efforts of urologists, medical oncologists, and radiation oncologists, patients who have genitourinary malignancies have an excellent chance of cure.

Correction of patient positioning errors based on in-line cone beam CTs: clinical implementation and first experiences

Background

The purpose of the study was the clinical implementation of a kV cone beam CT (CBCT) for setup correction in radiotherapy.

Patients and methods

For evaluation of the setup correction workflow, six tumor patients (lung cancer, sacral chordoma, head-and-neck and paraspinal tumor, and two prostate cancer patients) were selected. All patients were treated with fractionated stereotactic radiotherapy, five of them with intensity modulated radiotherapy (IMRT). For patient fixation, a scotch cast body frame or a vacuum pillow, each in combination with a scotch cast head mask, were used. The imaging equipment, consisting of an x-ray tube and a flat panel imager (FPI), was attached to a Siemens linear accelerator according to the in-line approach, i.e. with the imaging beam mounted opposite to the treatment beam sharing the same isocenter. For dose delivery, the treatment beam has to traverse the FPI which is mounted in the accessory tray below the multi-leaf collimator. For each patient, a predefined number of imaging projections over a range of at least 200 degrees were acquired. The fast reconstruction of the 3D-CBCT dataset was done with an implementation of the Feldkamp-David-Kress (FDK) algorithm. For the registration of the treatment planning CT with the acquired CBCT, an automatic mutual information matcher and manual matching was used.

Results and discussion

Bony landmarks were easily detected and the table shifts for correction of setup deviations could be automatically calculated in all cases. The image quality was sufficient for a visual comparison of the desired target point with the isocenter visible on the CBCT. Soft tissue contrast was problematic for the prostate of an obese patient, but good in the lung tumor case. The detected maximum setup deviation was 3 mm for patients fixated with the body frame, and 6 mm for patients positioned in the vacuum pillow. Using an action level of 2 mm translational error, a target point correction was carried out in 4 cases. The additional workload of the described workflow compared to a normal treatment fraction led to an extra time of about 10–12 minutes, which can be further reduced by streamlining the different steps.

Conclusion

The cone beam CT attached to a LINAC allows the acquisition of a CT scan of the patient in treatment position directly before treatment. Its image quality is sufficient for determining target point correction vectors. With the presented workflow, a target point correction within a clinically reasonable time frame is possible. This increases the treatment precision, and potentially the complex patient fixation techniques will become dispensable.

The potential of proton beam radiation therapy in prostate cancer, other urological cancers and gynaecological cancers

A group of Swedish oncologists and hospital physicists have estimated the number of patients in Sweden suitable for proton beam therapy. The estimations have been based on current statistics of tumour incidence, number of patients potentially eligible for radiation treatment, scientific support from clinical trials and model dose planning studies and knowledge of the dose-response relations of different tumours and normal tissues. In prostate cancer it is estimated that annually about 300 patients and in gynaecological cancer about 50 patients, are candidates for proton beam therapy. Owing to major uncertainties, it has not been possible to give an estimate of the number of potential patients with urinary bladder cancer.

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.

IMRT boost dose planning on dominant intraprostatic lesions: Gold marker-based three-dimensional fusion of CT with dynamic contrast-enhanced and 1H-spectroscopic MRI

PURPOSE

To demonstrate the theoretical feasibility of integrating two functional prostate magnetic resonance imaging (MRI) techniques (dynamic contrast-enhanced MRI [DCE-MRI] and 1H-spectroscopic MRI [MRSI]) into inverse treatment planning for definition and potential irradiation of a dominant intraprostatic lesion (DIL) as a biologic target volume for high-dose intraprostatic boosting with intensity-modulated radiotherapy (IMRT).

METHODS AND MATERIALS

In 5 patients, four gold markers were implanted. An endorectal balloon was inserted for both CT and MRI. A DIL volume was defined by DCE-MRI and MRSI using different prostate cancer-specific physiologic (DCE-MRI) and metabolic (MRSI) parameters. CT-MRI registration was performed automatically by matching three-dimensional gold marker surface models with the iterative closest point method. DIL-IMRT plans, consisting of whole prostate irradiation to 70 Gy and a DIL boost to 90 Gy, and standard IMRT plans, in which the whole prostate was irradiated to 78 Gy were generated. The tumor control probability and rectal wall normal tissue complication probability were calculated and compared between the two IMRT approaches.

RESULTS

Combined DCE-MRI and MRSI yielded a clearly defined single DIL volume (range, 1.1-6.5 cm3) in all patients. In this small, selected patient population, no differences in tumor control probability were found. A decrease in the rectal wall normal tissue complication probability was observed in favor of the DIL-IMRT plan versus the plan with IMRT to 78 Gy.

CONCLUSION

Combined DCE-MRI and MRSI functional image-guided high-dose intraprostatic DIL-IMRT planned as a boost to 90 Gy is theoretically feasible. The preliminary results have indicated that DIL-IMRT may improve the therapeutic ratio by decreasing the normal tissue complication probability with an unchanged tumor control probability. A larger patient population, with more variations in the number, size, and localization of the DIL, and a feasible mechanism for treatment implementation has to be studied to extend these preliminary tumor control and toxicity estimates.

Radiation therapy in the management of locally advanced prostate cancer

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

Cluster model analysis of late rectal bleeding after IMRT of prostate cancer: a case-control study

PURPOSE

Cluster models are newly developed normal-tissue complication probability models in which the spatial aspects of radiation-induced injury are taken into account by considering the size of spatially contiguous aggregates of damaged tissue units. The purpose of this study was to test the validity of a two-dimensional cluster model of late rectal toxicity based on maximum cluster size of damage to rectal surface.

METHODS AND MATERIALS

A paired case-control study was performed in which each of 9 patients experiencing Grade 2 or higher late rectal toxicity after intensity-modulated radiation therapy of localized prostate cancer was paired with a patient having a similar rectal dose-surface histogram but free of rectal toxicity. Numeric simulations were performed to determine the distribution of maximum cluster size on each rectal surface for each of many different choices of possible model parameters.

RESULTS

Model parameters were found for which patients with rectal toxicity were consistently more likely to have a significantly larger mean maximum cluster size than their matched controls. These parameter values correspond to a 50% probability of tissue-unit damage at doses near 30 Gy.

CONCLUSIONS

This study suggests that a cluster model based on maximum cluster size of damage to rectal surface successfully incorporates spatial information beyond that contained in the rectal dose-surface histogram and may therefore provide a useful new tool for predicting rectal normal-tissue complication probability after radiotherapy.

Combination of celecoxib with percutaneous radiotherapy in patients with localised prostate cancer - a phase I study

BACKGROUND

Current approaches for the improvement of bNED for prostate cancer patients treated with radiotherapy mainly focus on dose escalation. However molecularly targeted approaches may also turn out to be of value. In this regard cyclooxygenase (COX)-2 inhibitors have been shown to exert some anti-tumour activities in human prostate cancer in vivo and in vitro. Although in vitro data indicated that the combination of COX-2 inhibition and radiation was not associated with an increased toxicity, we performed a phase I trial using high dose celecoxib together with percutaneous radiation therapy.

METHODS

In order to rule out any increases of more than 20% incidence for a given side effect level 22 patients were included in the trial. Celecoxib was given 400 mg twice daily with onset of the radiation treatment. Risk adapted radiation doses were between 70 and 74 Gy standard fractionation. RTOG based gastrointestinal (GI) and genitourinary (GU) acute toxicity scoring was performed weekly during radiation therapy, at six weeks after therapy and three month after completing radiation treatment.

RESULTS

Generally no major increase in the level and incidence of side effects potentially caused by the combined treatment was observed. In two cases a generalised skin rash occurred which immediately resolved upon discontinuation of the drug. No grade 3 and 4 toxicity was seen. Maximal GI toxicity grade 1 and 2 was observed in 85% and 10%, respectively. In terms of GU toxicity 80% of the patients experienced a grade 1 toxicity and 10 % had grade 2 symptoms.

CONCLUSION

The combination of irradiation to the prostate with concurrent high dose celecoxib was not associated with an increased level of side effects.

Adverse effect of a distended rectum in intensity-modulated radiotherapy (IMRT) treatment planning of prostate cancer

BACKGROUND AND PURPOSE

The retrospective planning study for intensity-modulated radiotherapy (IMRT) of prostate cancer evaluated whether proximal rectum and supra-anal rectum/anal canal should be delineated as separated organs-at-risk (OARs) to achieve optimal dose distributions to the anorectal region.

PATIENTS AND METHODS

For 10 patients with localized prostate cancer IMRT plans were generated with the rectum and anal canal as separated OARs (Rec-sep) and as one single OAR (Rec-tot). Two different treatment planning systems (TPS) were utilized. Influence on dose distributions to target and OARs was analyzed.

RESULTS

Results from both TPS showed significantly increased doses to the distal rectum/anal canal for plans Rec-tot compared with Rec-sep in case of a distended rectum in the planning CT study: doses were increased by up to mean 31% (P = 0.02) and 18% (P = 0.03), respectively, in both TPS. For the patient with the largest rectum, the maximum dose increase was 61%. No significant differences in doses to target, bladder, femoral head and proximal rectum were seen.

CONCLUSIONS

For patients with a distended rectum in the planning CT, delineation of separated OARs for proximal rectum and distal rectum/anal canal resulted in superior dose distributions to the anorectal region and therefore, we recommend this as standard procedure for IMRT planning of prostate cancer.

The role of whole pelvic radiotherapy in locally advanced prostate cancer

Routine PSA testing has led to diagnosis and treatment of prostate cancer at earlier stages than previously. Earlier and technically-improved treatment, together with escalation of dose has enhanced cure rates. Although, the incidence of nodal metastases is now lower than in pre-PSA days, more extended pelvic lymphadenectomies have shown the actual rate of lymph node involvement to be higher than had been determined from standard radical prostate surgery. As in cancers in other sites, especially in their earlier stages, lymph node metastases may exist in the absence of haematogenous dissemination. This, together with the improved rates of control of the primary prostate tumour, suggests that elective irradiation of early-stage lymph nodes from prostate cancer should enhance survival in a manner analogous to improvements seen with this approach in other cancers. Although, the absolute incidence of positive nodes in locally advanced prostate cancer warrants elective radiotherapy, it is relatively low and the modest improvements to be expected may be undetected in the results of a small trial.

A prospective evaluation of rectal bleeding after dose-escalated three-dimensional conformal radiation therapy using an intrarectal balloon for prostate gland localization and immobilization

OBJECTIVES

To estimate the rates of rectal bleeding after dose-escalated three-dimensional conformal radiation therapy (3D-CRT) on a prospective, Phase II study in which a modified intrarectal balloon was used for prostate gland localization and immobilization.

METHODS

The study cohort comprised 100 men with biopsy-proven adenocarcinoma of the prostate and at least one high-risk feature (prostate-specific antigen level greater than 10 ng/mL, Gleason score 7 or higher, or clinical or radiographic T3 disease). Treatment consisted of androgen suppression therapy and four-field 3D-CRT with an intrarectal balloon for the initial 15 treatments. Planning treatment volume dose was 75.6 Gy. The primary endpoint of time to grade 3 rectal bleeding was estimated with the Kaplan-Meier method for 57 men with a minimum follow-up of 1 year.

RESULTS

For 57 men with a median (range) follow-up of 1.8 (1.0 to 3.3) years, the median (range) volume of rectum exceeding 70 Gy was 3.7 (0.6 to 14.7) cm3, and the 2-year estimate of grade 3 rectal bleeding rate was 10%. This rate was 100% as compared with 0 (P < 0.0001) for men who were taking warfarin (n = 3) or high-dose aspirin (n = 1) as compared with neither, respectively. All grade 3 rectal bleeding events were controlled with argon plasma coagulation.

CONCLUSIONS

Dose-escalated 3D-CRT with an intrarectal balloon technique for prostate localization and immobilization produced no measurable grade 3 rectal bleeding unless the patient was taking anticoagulants.

Radiation exposure after permanent prostate brachytherapy

BACKGROUND AND PURPOSE

Limited information is available on the true radiation exposure and associated risks for the relatives of the patients submitted to prostate brachytherapy with permanent implant of radioactive sources and for any other people coming into contact with them. In order to provide appropriate information, we analyzed the radiation exposure data from 216 prostate cancer patients who underwent (125)I or (103)Pd implants at the European Institute of Oncology of Milan, Italy.

PATIENTS AND METHODS

Between October 1999 and October 2004, 216 patients with low risk prostate carcinoma were treated with (125)I (200 patients) or (103)Pd (16 patients) permanent seed implantation. One day after the procedure, radiation exposure measurements around the patients were performed using an ionization chamber survey meter (Victoreen RPO-50) calibrated in dose rate at an accredited calibration center (calibration Centre SIT 104).

RESULTS

The mean dose rate at the posterior skin surface (gluteal region) following (125)I implants was 41.3 microSv/h (range: 6.2-99.4 microSv/h) and following (103)Pd implants was 18.9 microSv/h (range 5.0-37.3 microSv/h). The dose rate at 50 cm from the skin decreased to the mean value of 6.4 microSv/h for the (125)I implants and to the mean value of 1.7 microSv/h for the (103)Pd implants. Total times required to reach the annual dose limit (1 mSv/year) recommended for the general population by the European Directive 96/29/Euratom and by the Italian law (Decreto Legislativo 241/2000) at a distance of 50 cm from the posterior skin surface of the implanted patient would be 7.7 and 21.6 days for (125)I and for (103)Pd. Good correlation between the measured dose rates and both the total implanted activity and the distance between the most posteriorly implanted seed and the skin surface of the patients was found.

CONCLUSIONS

Our data show that the dose rates at 50 cm away from the prostate brachytherapy patients are very low and that the doses possibly absorbed by the relatives and other members of the general population coming into contact with the treated patients are well below the dose limit set by the European Directive and by the Italian regulation. However, in order to meet the recommendation of the ALARA principle (As Low As Reasonably/Readily Achievable), some advice to the patients should be given, such as to maintain a minimum distance from the patient of 1m, at least for a period equal to one half life of used radionuclide (60 days for (125)I and 15 days for (103)Pd).

An international multicenter study evaluating the impact of an alternative biochemical failure definition on the judgment of prostate cancer risk

PURPOSE

To evaluate the impact of an alternative biochemical failure (bF) definition on the performance of existing plus de novo prognostic models.

METHODS AND MATERIALS

The outcomes data of 1,458 Australian and 703 Canadian men treated with external-beam radiation monotherapy between 1993 and 1997 were analyzed using a lowest prostate-specific antigen (PSA) level to date plus 2 ng/mL (L + 2) bF definition. Two existing prognostic models were scrutinized using discrimination (Somers Dxy [SDxy]) and calibration indices. Alternative prognostic models were also created using recursive partitioning analysis (RPA) and multivariate nomogram methods for comparison.

RESULTS

Discrimination of bF was improved using the L + 2 definition compared with the American Society for Therapeutic Radiology and Oncology (ASTRO) definition using both the three-level risk model (SDxy 0.30 and 0.22, respectively) or the nomogram (SDxy 0.35 and 0.27, respectively). Both existing prognostic models showed only modest calibration accuracy. Using RPA, five distinct risk groups were identified based primarily on Gleason score (GS) and all subsequent divisions based on PSA. All GS 7-10 tumors were intermediate or high risk. This model and the developed nomogram showed improved discrimination over the existing models as well as accurate calibration against the Canadian data, apart from the 30-50% failure region.

CONCLUSIONS

The L + 2 definition of bF provides improved capacity for discrimination of failure risk. New prognostic models based on this endpoint have overall statistical performance superior to those based on the ASTRO consensus definition but continue to have unreliable discrimination in the intermediate-risk region.

Role of radiotherapy with surgery for T3 and resectable T4 rectal cancer: evidence from randomized trials

PURPOSE

The main treatment for resectable rectal cancer T2-T4 N0-N2 M0 is surgery. The benefit of preoperative or postoperative radiation therapy can be analyzed in terms of improvement of local control, sphincter preservation, and survival weighted against increased toxicity.

METHODS

Only randomized trials can provide strong evidence of a positive cost-benefit ratio of such combined approach. The most recent trials were reviewed.

RESULTS

Three randomized trials, including the latest German CAO-ARO trial, have demonstrated the superiority of preoperative radiotherapy with or without chemotherapy (vs. postoperative) in terms of local control and toxicity. The Ducth TME trial showed that even with modern standard surgery, preoperative radiotherapy improved local control. Preoperative irradiation using a high dose in a small volume and a long interval before surgery may improve sphincter preservation (Lyon trials). Concurrent chemoradiation (FFCD 9203, EORTC 22921, did not significantly improve sphincter preservation or survival but significantly reduced the local recurrence rate.

CONCLUSIONS

In 2005 examination of randomized trials provides evidence for the benefit of preoperative chemoradiation in improving local control and probably sphincter preservation in rectal cancer. Randomized trials should be designed to further demonstrate improved sphincter preservation and to increase survival using adjuvant medical treatments.

Integral radiation dose to normal structures with conformal external beam radiation

BACKGROUND

This study was designed to evaluate the integral dose (ID) received by normal tissue from intensity-modulated radiotherapy (IMRT) for prostate cancer.

METHODS AND MATERIALS

Twenty-five radiation treatment plans including IMRT using a conventional linac with both 6 MV (6MV-IMRT) and 20 MV (20MV-IMRT), as well as three-dimensional conformal radiotherapy (3DCRT) using 6 MV (6MV-3DCRT) and 20 MV (20MV-3DCRT) and IMRT using tomotherapy (6MV) (Tomo-IMRT), were created for 5 patients with localized prostate cancer. The ID (mean dose x tissue volume) received by normal tissue (NTID) was calculated from dose-volume histograms.

RESULTS

The 6MV-IMRT resulted in 5.0% lower NTID than 6MV-3DCRT; 20 MV beam plans resulted in 7.7%-11.2% lower NTID than 6MV-3DCRT. Tomo-IMRT NTID was comparable to 6MV-IMRT. Compared with 6MV-3DCRT, 6MV-IMRT reduced IDs to the rectal wall and penile bulb by 6.1% and 2.7%, respectively. Tomo-IMRT further reduced these IDs by 11.9% and 16.5%, respectively. The 20 MV did not reduce IDs to those structures.

CONCLUSIONS

The difference in NTID between 3DCRT and IMRT is small. The 20 MV plans somewhat reduced NTID compared with 6 MV plans. The advantage of tomotherapy over conventional IMRT and 3DCRT for localized prostate cancer was demonstrated in regard to dose sparing of rectal wall and penile bulb while slightly decreasing NTID as compared with 6MV-3DCRT.

Localized volume effects for late rectal and anal toxicity after radiotherapy for prostate cancer

PURPOSE

To identify dosimetric parameters derived from anorectal, rectal, and anal wall dose distributions that correlate with different late gastrointestinal (GI) complications after three-dimensional conformal radiotherapy for prostate cancer.

METHODS AND MATERIALS

In this analysis, 641 patients from a randomized trial (68 Gy vs. 78 Gy) were included. Toxicity was scored with adapted Radiation Therapy Oncology Group/European Organization for the Research and Treatment of Cancer (RTOG/EORTC) criteria and five specific complications. The variables derived from dose-volume histogram of anorectal, rectal, and anal wall were as follows: % receiving > or =5-70 Gy (V5-V70), maximum dose (Dmax), and mean dose (D(mean)). The anus was defined as the most caudal 3 cm of the anorectum. Statistics were done with multivariate Cox regression models. Median follow-up was 44 months.

RESULTS

Anal dosimetric variables were associated with RTOG/EORTC Grade > or =2 (V5-V40, D(mean)) and incontinence (V5-V70, D(mean)). Bleeding correlated most strongly with anorectal V55-V65, and stool frequency with anorectal V40 and D(mean). Use of steroids was weakly related to anal variables. No volume effect was seen for RTOG/EORTC Grade > or =3 and pain/cramps/tenesmus.

CONCLUSION

Different volume effects were found for various late GI complications. Therefore, to evaluate the risk of late GI toxicity, not only intermediate and high doses to the anorectal wall volume should be taken into account, but also the dose to the anal wall.

Sustained long-term immune responses after in situ gene therapy combined with radiotherapy and hormonal therapy in prostate cancer patients

PURPOSE

To explore long-term immune responses after combined radio-gene-hormonal therapy.

METHODS AND MATERIALS

Thirty-three patients with prostate specific antigen 10 or higher or Gleason score of 7 or higher or clinical stage T2b to T3 were treated with gene therapy that consisted of 3 separate intraprostatic injections of AdHSV-tk on Days 0, 56, and 70. Each injection was followed by 2 weeks of valacyclovir. Intensity-modulated radiation therapy was delivered 2 days after the second AdHSV-tk injection for 7 weeks. Hormonal therapy was initiated on Day 0 and continued for 4 months or 2.3 years. Blood samples were taken before, during, and after treatment. Lymphocytes were analyzed by fluorescent antibody cell sorting (FACS).

RESULTS

Median follow-up was 26 months (range, 4-48 months). The mean percentages of DR+CD8+ T cells were increased at all timepoints up to 8 months. The mean percentages of DR+CD4+ T cells were increased later and sustained longer until 12 months. Long-term (2.3 years) use of hormonal therapy did not affect the percentage of any lymphocyte population.

CONCLUSIONS

Sustained long-term (up to 8 to 12 months) systemic T-cell responses were noted after combined radio-gene-hormonal therapy for prostate cancer. Prolonged use of hormonal therapy does not suppress this response. These results suggest the potential for sustained activation of cell-mediated immune responses against cancer.

Radiotherapy Treatment Verification in the UK: An Audit of Practice in 2004

AIMS

To audit current practice related to treatment verification undertaken in radiotherapy departments throughout the UK.

MATERIALS AND METHODS

A questionnaire was circulated to the radiotherapy service managers of 62 radiotherapy centres in the UK. This looked in detail at the department demographics, imaging equipment, site-specific verification protocols, and training and competency assessment of staff responsible for verification.

RESULTS

The response rate was 48% (30/62). All departments were using megavoltage imaging equipment in routine clinical practice. Twenty-four out of 29 (83%) departments that had electronic portal imaging capability were using image analysis software for verification. Twenty-nine out of 30 (97%) departments had site-specific written verification protocols. Twenty out of 30 (67%) treatment centres audited set-up errors within their department. Forty-three per cent of centres were using simulator image as the reference image of choice across all sites. Electronic portal imaging, alone or in combination with portal film, was being used for verification in 75% of the centres. Fifty-three per cent of centres used off-line correction strategies for measuring set-up errors across all sites. Radiographer-led interventions were primarily in the pelvis.

CONCLUSION

Presently in the UK, verification strategies vary widely at individual treatment sites and between departments. Dedicated departmental verification teams, with input from radiographers, physicists and clinicians, may assist in the effective implementation of evidence-based verification. The inclusion of comprehensive verification protocols within multicentre radiotherapy trials encourages standardisation across treatment centres.

The Effect of Radiation Therapy on Normal Tissue Function

As more patients are treated for their primary malignancy with cure or increased disease-free intervals, injury to normal tissues will become more detectable and an important endpoint for study. Future protocols will probably be modified based on toxicity endpoints. In Hodgkin's disease, current protocols use response-based treatment strategies to limit therapy. The objective is to provide the same level of tumor control and follow normal tissue endpoints for outcome analysis. DVH analysis has improved the ability to analyze endpoint data for normal tissues. These image-guided platforms will provide the infrastructure needed to continue efforts in improving the delivery of radiation therapy.