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

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

PURPOSE

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

METHODS AND MATERIALS

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

RESULTS

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

CONCLUSION

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

Dose escalation with proton or photon radiation treatment for pancreatic cancer

PURPOSE

The purpose was to determine the optimal radiation therapy modality (three-dimensional conformal photon-radiation therapy [3DCRT], intensity-modulated photon-radiation therapy [IMRT], or passive-scattering proton therapy [PT]) for safe dose escalation (72Gy) in pancreatic tumors in different positions relative to organs at risk (OAR) anatomy.

METHODS AND MATERIALS

A 3-cm pancreatic tumor was virtually translated every 5mm over 5cm laterally. We generated two plans for each of the three techniques (3DCRT, IMRT, and PT), one that adhered to target coverage objectives and another to meet OAR sparing constraints with best coverage. We evaluated distances between gross tumor volumes and isodoses and compared dose-volume histograms.

RESULTS

IMRT was more conformal in higher gradient dose regions circumferentially, but tumor positions with anteriorly located small bowel benefited more from PT. 3DCRT plans resulted in inadequate target coverage. The V(15Gy) (mean+/-SD) were as follows for the IMRT and PT plans, respectively: stomach, 48%+/-4% vs 5%+/-3% (p<0.0001); and small bowel, 61%+/-8% vs 9%+/-4% (p<0.0001).

CONCLUSIONS

Our study showed that the optimal radiation therapy modality for safe dose escalation depends on pancreatic tumor position in relation to OAR anatomy.

Comparison of rectal volume definition techniques and their influence on rectal toxicity in patients with prostate cancer treated with 3D conformal radiotherapy: a dose-volume analysis

BACKGROUND

To evaluate the impact of four different rectum contouring techniques and rectal toxicities in patients with treated with 3D conformal radiotherapy (3DCRT).

METHODS

Clinical and dosimetric data were evaluated for 94 patients who received a total dose 3DCRT of 70 Gy, and rectal doses were compared in four different rectal contouring techniques: the prostate-containing CT sections (method 1); 1 cm above and below the planning target volume (PTV) (method 2); 110 mm starting from the anal verge (method 3); and from the anal verge to the sigmoid flexure (method 4). The percentage of rectal volume receiving RT doses (30-70 Gy) and minimum, mean rectal doses were assessed.

RESULTS

Median age was 69 years. Percentage of rectal volume receiving high doses (>or= 70 Gy) were higher with the techniques that contoured smaller rectal volumes. In methods 2 and 3, the percentage of rectal volume receiving >or= 70 Gy was significantly higher in patients with than without rectal bleeding (method 2: 30.8% vs. 22.5%, respectively (p = 0.03); method 3: 26.9% vs. 18.1%, respectively (p = 0.006)). Mean rectal dose was significant predictor of rectal bleeding only in method 3 (48.8 Gy in patients with bleeding vs. 44.4 Gy in patients without bleeding; p = 0.02).

CONCLUSION

Different techniques of rectal contouring significantly influence the calculation of radiation doses to the rectum and the prediction of rectal toxicity. Rectal volume receiving higher doses (>or= 70 Gy) and mean rectal doses may significantly predict rectal bleeding for techniques contouring larger rectal volumes, as was in method 3.

Retrospective comparison of external beam radiotherapy and radical prostatectomy in high-risk, clinically localized prostate cancer

PURPOSE

Because of the lack of conclusive and well-conducted randomized studies, the optimal therapy for prostate tumors remains controversial. The aim of this study was to retrospectively compare the results of radical surgery vs. a conservative approach such as external beam radiotherapy (EBRT) plus androgen deprivation therapy using an intent-to-treat analysis on two pretreatment defined, concurrently treated, high-risk patient populations.

METHODS AND MATERIALS

Between January 2003 and December 2007, 162 patients with high-risk prostate cancer underwent an EBRT plus androgen deprivation therapy program at the RT department of our institute. In the same period, 122 patients with the same high-risk disease underwent radical prostatectomy (RP) at the urologic department of our institute. Patients with adverse pathologic factors also underwent adjuvant EBRT with or without androgen deprivation therapy. The primary endpoint was freedom from biochemical failure.

RESULTS

The two groups of high-risk patients were homogeneous in terms of freedom from biochemical failure on the basis of the clinical T stage, biopsy Gleason score, and initial prostate-specific antigen level. The median follow-up was 38.6 and 33.8 months in the EBRT and RP groups, respectively. The actuarial analysis of the freedom from biochemical failure showed a 3-year rate of 86.8% and 69.8% in the EBRT and RP group, respectively (p = .001). Multivariate analysis of the whole group revealed the initial prostate-specific antigen level and treatment type (EBRT vs. RP) as significant covariates.

CONCLUSION

This retrospective intention-to-treat analysis showed a significantly better outcome after EBRT than after RP in patients with high-risk prostate cancer, although a well-conducted randomized comparison would be the best procedure to confirm these results.

Radioterapia externa conformada 3D para o carcinoma de próstata: experiência do Instituto do Radium de Campinas com 285 pacientes

OBJETIVO: Reportar resultados de tratamentos do câncer de próstata com radioterapia conformada 3D realizados em uma única instituição. MATERIAIS E MÉTODOS: De julho de 1997 a janeiro de 2002, 285 pacientes consecutivos com câncer de próstata foram submetidos a radioterapia conformada 3D com dose mediana de 7.920 cGy na próstata e analisados retrospectivamente. A distribuição segundo o grupo de risco foi a seguinte: baixo risco - 95 (33,7%); risco intermediário - 66 (23,4%); alto risco - 121 (42,9%) pacientes. RESULTADOS: Em seguimento mediano de 53,6 meses (3,6-95,3 meses), sobrevidas atuariais global, causa específica, livre de metástases a distância e livre de recidiva bioquímica em cinco anos foram de 85,1%, 97,0%, 94,2% e 75,8%, respectivamente. Sobrevidas atuariais livre de toxicidade retal e urinária tardias em cinco anos foram de 96,4% e 91,1%, respectivamente. Ressecção transuretral pré-radioterapia conformada 3D e doses > 70 Gy em 30% do volume da bexiga implicaram maior toxicidade urinária tardia grau 2-3 em cinco anos (p = 0,0002 e p = 0,0264, respectivamente). CONCLUSÃO: A primeira experiência relatada de radioterapia conformada 3D no Brasil permitiu altas doses de radiação, com toxicidades retal e urinária aceitáveis. A existência de ressecção transuretral de próstata pré-radioterapia conformada 3D pode sinalizar maior risco de toxicidade urinária tardia grau 2-3 após irradiação. Restrição da dose < 70 Gy em 30% do volume da bexiga à tomografia de planejamento pode reduzir complicações urinárias tardias.

kV-Cone Beam CT as an IGRT Tool in the Treatment of Early Stage Prostate Cancer: A Literature Review

Image-guided radiation therapy (IGRT) is an important quality assurance measure that can be used in tandem with conformal radiation therapy treatment. Cone beam computed tomography (CBCT) is a sophisticated IGRT technology that has recently been introduced to the clinical setting. Cone beam equipment includes kilovoltage (kV) CBCT that produces online, high-quality, three-dimensional images of the prostate gland. Interfractional displacements of the prostate can be quantified and adjustments made using kV-CBCT so that daily RT can be accurately delivered. In addition, the volumetric nature of CBCT allows deformations of the prostate gland and surrounding anatomy to be accounted for using adaptive radiation therapy strategies. This article provides an introduction to the main IGRT tools that can be used in parallel with conformal radiation therapy of prostate cancer. A literature review is performed to describe the major IGRT approaches; however, the focus will remain primarily on the technical and clinical applications of kV-CBCT. Important considerations including patient dose, resource implications, and possible changes to the radiation therapist's scope of practice are also discussed.

On the impact of functional imaging accuracy on selective boosting IMRT

In order to quantify the impact of loss of functional imaging sensitivity and specificity on tumor control and normal tissue toxicity for selective boosting IMRT four selective boosting scenarios were designed: SB91-81 (EUD=91Gy for the high-risk tumor subvolume and EUD=81Gy for a remaining low-risk PTV (rPTV)), SB80-74, SB90-70, and risk-adaptive optimization. For each sensitivity loss level the loss in tumor control probability (DeltaTCP) was calculated. For each specificity loss level, the increase in rectal and bladder toxicity was quantified using the radiobiological indices (equivalent uniform dose (EUD) and normal tissue complication probability (NTCP)) as well as %-volumes irradiated. The impact of loss in sensitivity on local tumor control was maximal when the prescription dose level for rPTV had the lowest value. The SB90-70 plan had a DeltaTCP=29.6%, the SB91-81 plan had a DeltaTCP=9.5%, while for risk-adaptive optimization a DeltaTCP=4.7% was found. Independent of planning technique loss in functional imaging specificity appears to have a minimal impact on the expected normal tissue toxicity, since an increase in rectal or bladder toxicity as a function of loss in specificity was not observed. Additionally, all plans fulfilled the rectum and the bladder sparing criteria found in the literature for late rectal bleeding and genitourinary complications. Our study shows that the choice of a low-risk classification for the rPTV in selective boosting IMRT may lead to a significant loss in TCP. Furthermore, for the example considered in which normal tissue complications can be limited through the use of a tissue expander it appears that the therapeutic ratio can be improved using a functional imaging technique with a high sensitivity and limited specificity; while for cases were this is not possible, an optimal balance between sensitivity and specificity has to be found.

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

PURPOSE

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSION

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

Genitourinary toxicity after high-dose-rate (HDR) brachytherapy combined with Hypofractionated External beam radiotherapy for localized prostate cancer: an analysis to determine the correlation between dose-volume histogram parameters in HDR brachytherapy and severity of toxicity

PURPOSE

To evaluate the severity of genitourinary (GU) toxicity in high-dose-rate (HDR) brachytherapy combined with hypofractionated external beam radiotherapy (EBRT) for prostate cancer and to explore factors that might affect the severity of GU toxicity.

METHODS AND MATERIALS

A total of 100 Japanese men with prostate cancer underwent (192)Ir HDR brachytherapy combined with hypofractionated EBRT. Mean (SD) dose to 90% of the planning target volume was 6.3 (0.7) Gy per fraction of HDR. After 5 fractions of HDR treatment, EBRT with 10 fractions of 3 Gy was administrated. The urethral volume receiving 1-15 Gy per fraction in HDR brachytherapy (V1-V15) and the dose to at least 5-100% of urethral volume in HDR brachytherapy (D5-D100) were compared between patients with Grade 3 toxicity and those with Grade 0-2 toxicity. Prostate volume, patient age, and International Prostate Symptom Score were also compared between the two groups.

RESULTS

Of the 100 patients, 6 displayed Grade 3 acute GU toxicity, and 12 displayed Grade 3 late GU toxicity. Regarding acute GU toxicity, values of V1, V2, V3, and V4 were significantly higher in patients with Grade 3 toxicity than in those with Grade 0-2 toxicity. Regarding late GU toxicity, values of D70, D80, V12, and V13 were significantly higher in patients with Grade 3 toxicity than in those with Grade 0-2 toxicity.

CONCLUSIONS

The severity of GU toxicity in HDR brachytherapy combined with hypofractionated EBRT for prostate cancer was relatively high. The volume of prostatic urethra was associated with grade of acute GU toxicity, and urethral dose was associated with grade of late GU toxicity.

Planning and delivery of intensity-modulated radiation therapy

Intensity modulated radiation therapy (IMRT) is an advanced form of external beam radiation therapy. IMRT offers an additional dimension of freedom as compared with field shaping in three-dimensional conformal radiation therapy because the radiation intensities within a radiation field can be varied according to the preferences of locations within a given beam direction from which the radiation is directed to the tumor. This added freedom allows the treatment planning system to better shape the radiation doses to conform to the target volume while sparing surrounding normal structures. The resulting dosimetric advantage has shown to translate into clinical advantages of improving local and regional tumor control. It also offers a valuable mechanism for dose escalation to tumors while simultaneously reducing radiation toxicities to the surrounding normal tissue and sensitive structures. In less than a decade, IMRT has become common practice in radiation oncology. Looking forward, the authors wonder if IMRT has matured to such a point that the room for further improvement has diminished and so it is pertinent to ask what the future will hold for IMRT. This article attempts to look from the perspective of the current state of the technology to predict the immediate trends and the future directions. This article will (1) review the clinical experience of IMRT; (2) review what we learned in IMRT planning; (3) review different treatment delivery techniques; and finally, (4) predict the areas of advancements in the years to come.

Influence of daily setup measurements and corrections on the estimated delivered dose during IMRT treatment of prostate cancer patients

PURPOSE

To evaluate the impact of marker-based position verification, using daily imaging and an off-line correction protocol, by calculating the delivered dose to prostate, rectum and bladder.

METHODS

Prostate cancer patients (n=217) were treated with IMRT, receiving 35 daily fractions. Plans with five beams were optimized taking target coverage (CTV, boost) and organs-at-risk (rectum and bladder) into account. PTV margins were 8mm. Prostate position was verified daily using implanted fiducial gold markers by imaging the first segment of all the five beams on an EPID. Setup deviations were corrected off-line using an adapted shrinking-action-level protocol. The estimated delivered dose, including daily organ movements, was calculated using a version of PLATO's dose engine, enabling batch processing of large numbers of patients. The dose was calculated +/- inclusion of setup corrections, and was evaluated relative to the original static plan. The marker-based measurements were considered representative for all organs.

RESULTS

Daily organ movements would result in an underdosage of 2-3Gy to CTV and boost volume relative to the original plan, which was prevented by daily setup corrections. The dose to rectum and bladder was on average unchanged, but a large spread was introduced by organ movements, which was reduced by including setup corrections.

CONCLUSIONS

Without position verification and setup corrections, margins of 8mm would be insufficient to account for position uncertainties during IMRT of prostate cancer. With the daily off-line correction protocol, the remaining variations are accommodated adequately.

Conventional treatments of localized prostate cancer

Established therapeutic approaches for clinically localized prostate cancer include watchful waiting (active surveillance), radical prostatectomy, and radiotherapy. The risk of progression during surveillance is related to the initial cancer stage and grade; reasonable evidence has supported the safety and feasibility, during a period of 5-10 years, of an active surveillance regimen for men with low-risk prostate cancer. The progression rates at >10 years have not yet been studied in modern trials. Patients with low-risk tumor characteristics can be actively monitored without sacrificing the possibility of cure and without being exposed to an undue risk of disease progression, although some patients will not accept the emotional burden of living with an untreated cancer. Focal ablation might be an attractive alternative to active surveillance for some patients with low-risk cancer, if it proves to have minimal adverse effects on their quality of life. Radical prostatectomy is an effective form of therapy for patients with clinically significant prostate cancer; however, outcomes are highly sensitive to variations in surgical technique. Because of the risks of perioperative complications and urinary and sexual dysfunction, which appear to be as great with robotic-assisted prostatectomy as with any other technique, patients with low-risk cancer, especially those >60 years, might be attracted to more conservative alternatives, including active surveillance, radiotherapy, and focal ablation. External beam radiotherapy is an effective, noninvasive form of therapy, but it carries the long-term risks of troublesome bowel and sexual and urinary dysfunction. It might be too aggressive for many low-risk cancers detected in screened populations. For more aggressive cancers, local recurrence after radiotherapy carries substantial morbidity and low rates of long-term cancer control. Brachytherapy, a convenient, effective form of radiotherapy, is targeted at selected patients with clinically confined cancer and a prostate size of <60 g without evidence of extraprostatic extension on imaging. However, excellent outcomes require meticulous technique; acute urinary symptoms are frequent; and the long-term risks of proctitis and erectile dysfunction are comparable to the risks associated with external beam radiotherapy. Androgen-deprivation therapy is not recommended for men with localized prostate cancer who would otherwise be candidates for surgery or radiotherapy, because, even with short-term use, the risk of side effects, including osteopenic fracture and major cardiovascular events, serious. For locally extensive cancer, androgen-deprivation therapy should be used alone only for the relief of local symptoms in men with a life expectancy of <5 years who are not eligible for more aggressive treatment.

Evaluating the relationships between rectal normal tissue complication probability and the portion of seminal vesicles included in the clinical target volume in intensity-modulated radiotherapy for prostate cancer

PURPOSE

To compare dose-volume consequences of the inclusion of various portions of the seminal vesicles (SVs) in the clinical target volume (CTV) in intensity-modulated radiotherapy (IMRT) for patients with prostate cancer.

METHODS AND MATERIALS

For 10 patients with prostate cancer, three matched IMRT plans were generated, including 1 cm, 2 cm, or the entire SVs (SV1, SV2, or SVtotal, respectively) in the CTV. Prescription dose (79.2 Gy) and IMRT planning were according to the high-dose arm of the Radiation Therapy Oncology Group (RTOG) 0126 protocol. We compared plans for percentage of rectal volume receiving minimum doses of 60-80 Gy and for rectal normal tissue complication probability (NTCP[R]).

RESULTS

There was a detectable increase in rectal dose in SV2 and SVtotal compared with SV1. The magnitude of difference between plans was modest in the high-dose range. In 2 patients, there was underdosing of the planning target volume (PTV) because of constraints on rectal dose in the SVtotal plans. All other plans were compliant with RTOG 0126 protocol requirements. Mean NTCP increased from 14% to 17% and 18% for SV1, SV2, and SV total, respectively. The NTCP correlated with the size of PTV-rectum volume overlap (Pearson's r = 0.86; p < 0.0001), but not with SV volume.

CONCLUSIONS

Doubling (1 to 2 cm) or comprehensively increasing (1 cm to full SVs) SV volume included in the CTV for patients with prostate IMRT is achievable in the majority of cases without exceeding RTOG dose-volume limits or underdosing the PTV and results in only a moderate increase in NTCP.

Endocrine treatment, with or without radiotherapy, in locally advanced prostate cancer (SPCG-7/SFUO-3): an open randomised phase III trial

BACKGROUND

Several studies have shown the efficacy of endocrine therapy in combination with radiotherapy in high-risk prostate cancer. To assess the effect of radiotherapy, we did an open phase III study comparing endocrine therapy with and without local radiotherapy, followed by castration on progression.

METHODS

This randomised trial included men from 47 centres in Norway, Sweden, and Denmark. Between February, 1996, and December, 2002, 875 patients with locally advanced prostate cancer (T3; 78%; PSA<70; N0; M0) were centrally randomly assigned by computer to endocrine treatment alone (3 months of total androgen blockade followed by continuous endocrine treatment using flutamide; 439 patients), or to the same endocrine treatment combined with radiotherapy (436 patients). The primary endpoint was prostate-cancer-specific survival, and analysis was by intention to treat. This study is registered as an international standard randomised controlled trial, number ISRCTN01534787.

FINDINGS

After a median follow-up of 7.6 years, 79 men in the endocrine alone group and 37 men in the endocrine plus radiotherapy group had died of prostate cancer. The cumulative incidence at 10 years for prostate-cancer-specific mortality was 23.9% in the endocrine alone group and 11.9% in the endocrine plus radiotherapy group (difference 12.0%, 95% CI 4.9-19.1%), for a relative risk of 0.44 (0.30-0.66). At 10 years, the cumulative incidence for overall mortality was 39.4% in the endocrine alone group and 29.6% in the endocrine plus radiotherapy group (difference 9.8%, 0.8-18.8%), for a relative risk of 0.68 (0.52-0.89). Cumulative incidence at 10 years for PSA recurrence was substantially higher in men in the endocrine-alone group (74.7%vs 25.9%, p<0.0001; HR 0.16; 0.12-0.20). After 5 years, urinary, rectal, and sexual problems were slightly more frequent in the endocrine plus radiotherapy group.

INTERPRETATION

In patients with locally advanced or high-risk local prostate cancer, addition of local radiotherapy to endocrine treatment halved the 10-year prostate-cancer-specific mortality, and substantially decreased overall mortality with fully acceptable risk of side-effects compared with endocrine treatment alone. In the light of these data, endocrine treatment plus radiotherapy should be the new standard.

Analysis of interfraction prostate motion using megavoltage cone beam computed tomography

PURPOSE

Determine the degree of interfraction prostate motion and its components measured by using daily megavoltage (MV) cone beam computed tomography (CBCT) imaging.

METHODS AND MATERIALS

A total of 984 daily MV CBCT images from 24 patients undergoing definitive intensity-modulated radiotherapy for localized prostate cancer were analyzed retrospectively. Pretreatment couch shifts, based on physician registration of MV CBCT to planning CT data sets, were used as a measure of daily interfraction motion. Off-line bony registration was performed to separate bony misalignment from internal organ motion. Interobserver and intraobserver variation studies were performed on 20 MV CBCT images.

RESULTS

Mean interfraction prostate motion was 6.7 mm, with the greatest single-axis deviation in the anterior-posterior (AP) direction. The largest positional inaccuracy was accounted for by systematic deviations in bony misalignment, whereas random deviations occurred from bony misalignment and internal prostate motion. In the aggregate, AP motion did not correlate with days elapsed since beginning therapy or on average with rectal size at treatment planning. Interobserver variation was greatest in the AP direction, decreased in experienced observers, and further decreased in intraobserver studies. Mean interfraction motion during the first 6 days of therapy, when used as a subsequent offset, reduced acceptable AP planning target volume margins by 50%.

CONCLUSION

The MV CBCT is a practical direct method of daily localization that shows significant interfraction motion with respect to conventional three-dimensional conformal and intensity-modulated radiotherapy margins, similar to that measured in other modalities.

Urethral stricture following high dose rate brachytherapy for prostate cancer

PURPOSE

To evaluate the incidence, timing, nature and outcome of urethral strictures following high dose rate brachytherapy (HDRB) for prostate carcinoma.

METHODS AND MATERIALS

Data from 474 patients with clinically localised prostate cancer treated with HDRB were analysed. Ninety percent received HDRB as a boost to external beam radiotherapy (HDRBB) and the remainder as monotherapy (HDRBM). Urethral strictures were graded according to the Common Terminology Criteria for Adverse Events v3.0.

RESULTS

At a median follow-up of 41 months, 38 patients (8%) were diagnosed with a urethral stricture (6-year actuarial risk 12%). Stricture location was bulbo-membranous (BM) urethra in 92.1%. The overall actuarial rate of grade 2 or more BM urethral stricture was estimated at 10.8% (95% CI 7.0-14.9%), with a median time to diagnosis of 22 months (range 10-68 months). All strictures were initially managed with either dilatation (n=15) or optical urethrotomy (n=20). Second line therapy was required in 17 cases (49%), third line in three cases (9%) and 1 patient open urethroplasty (grade 3 toxicity). Predictive factors on multivariate analysis were prior trans-urethral resection of prostate (hazard ratio (HR) 2.81, 95% CI 1.15-6.85, p=0.023); hypertension (HR 2.83, 95% CI 1.37-5.85, p=0.005); and dose per fraction used in HDR (HR for 1 Gy increase per fraction 1.33, 95% CI 1.08-1.64, p=0.008).

CONCLUSIONS

BM urethral strictures are the most common late grade 2 or more urinary toxicity following HDR brachytherapy for prostate cancer. Most are manageable with minimally invasive procedures. Both clinical and dosimetric factors appear to influence the risk of stricture formation.

Reduced rectal toxicity with ultrasound-based image guided radiotherapy using BAT (B-mode acquisition and targeting system) for prostate cancer

PURPOSE

To evaluate the effect of image guided radiotherapy with stereotactic ultrasound BAT (B-mode acquisition and targeting system) on rectal toxicity in conformal radiotherapy of prostate cancer.

PATIENTS AND METHODS

42 sequential patients with prostate cancer undergoing radiotherapy before and after the introduction of BAT were included. Planning computed tomography (CT) was performed with empty rectum and moderately filled bladder. The planning target volume (PTV) included the prostate and seminal vesicles with a safety margin of 1.5 cm in anterior and lateral direction. In posterior direction the anterior 1/3 of the rectum circumference were included. Total dose was 66 Gy and a boost of 4 Gy excluding the seminal vesicles. 22 patients (BAT group) were treated with daily stereotactic ultrasound positioning, for the other 20 patients (NoBAT group) an EPID (electronic portal imaging device) was performed once a week. Acute and late genito-urinary (GU) and rectal toxicity and PSA values were evaluated after 1.5, 3, 6, 9 and 12 months. The total median follow up of toxicity was 3 years in the BAT group and 4 years in the NoBAT group.

RESULTS

In the NoBAT group significant more rectal toxicity occurred, while in GU toxicity no difference was seen. Two patients in the NoBAT group showed late rectal toxicity grade 3, no toxicity>grade 2 occurred in the BAT group. There was no significant difference in PSA reduction between the groups.

CONCLUSION

Without BAT significant more acute and a trend to more late rectal toxicity was found. With regard to dose escalation this aspect is currently evaluated with a larger number of patients using intensity-modulated radiotherapy (IMRT).

Management of locally advanced prostate cancer

The management of all stages of prostate cancer is an increasingly complex process and involves a variety of available treatments and many disciplines. Despite prostate-specific antigen (PSA) testing, the presentation of prostate cancer at a locally advanced stage is common in the UK, accounting for one-third of all new cases. There is no universally accepted definition of locally advanced prostate cancer; the term is loosely used to encompass a spectrum of disease profiles that show high-risk features. Men with high-risk prostate cancer generally have a significant risk of disease progression and cancer-related death if left untreated. High-risk patients, including those with locally advanced disease, present two specific challenges. There is a need for local control as well as a need to treat any microscopic metastases likely to be present but undetectable until disease progression. The optimal treatment approach will therefore often necessitate multiple modalities. The exact combinations, timing and intensity of treatment continue to be strongly debated. Management decisions should be made after all treatments have been discussed by a multidisciplinary team (including urologists, oncologists, radiologists, pathologists and nurse specialists) and after the balance of benefits and side effects of each therapy modality has been considered by the patient with regard to his own individual circumstances. This article reviews the current therapy options.

Definitive radiotherapy for prostate cancer

The probability of extraprostatic disease may be estimated based on clinical T-stage, pretreatment prostatic-specific antigen, Gleason score, and percent positive core biopsies. Patients with disease confined to the prostate may be treated with either prostatectomy or radiotherapy (RT). Patients with extraprostatic disease without evidence of distant metastases are best managed with RT. RT consisting of either external beam and/or brachytherapy results in a relatively high likelihood of cure, particularly for those with low- and intermediate-risk disease. The impact of elective nodal RT on survival is unclear. Dose escalation results in improved biochemical relapse-free survival compared with standard dose RT. Androgen deprivation therapy likely improves the probability of disease control in patients with high-risk cancers.

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

Background

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

Methods

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

Results

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

Discussion

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

Health-related quality of life 3 years after high-dose intensity-modulated radiotherapy with gold fiducial marker-based position verification

OBJECTIVE

To evaluate the change in quality of life (QoL) 3 years after high-dose intensity-modulated radiotherapy (IMRT) using gold fiducial marker-based position verification in patients with locally advanced prostate cancer.

PATIENTS AND METHODS

Between October 2003 and November 2004, 95 patients with locally advanced prostate cancer were treated with 76 Gy IMRT with gold-fiducial marker-based position verification. Before treatment (baseline) and 1, 6 and 36 months after RT the QoL was measured using the RAND-36, the European Organization for Research and Treatment of Cancer (EORTC) core questionnaire (QLQ-C30(+3)) and the prostate tumour-specific module (EORTC QLQ-PR25). Changes in QoL with time of > or =10 points were considered clinically relevant.

RESULTS

After 3 years there was a statistically significant improvement in QoL for emotional role restriction and functioning, change in health, mental health and insomnia, compared with baseline. Emotional role restriction increased by >10 points and was therefore clinically relevant, while all other differences were of <10 points. There was a statistically significant deterioration of QoL after 3 years in physical and cognitive functioning, bowel symptoms/function and sexual activity. Only the sexual activity QoL score changed by 12 points and was therefore the only meaningful deterioration in QoL at 3 years after treatment.

CONCLUSION

IMRT and accurate position verification provide the possibility to deliver a high irradiation dose to the prostate without clinically relevant deterioration in long-term QoL, except for a persistent decrease in sexual activity score.

Intrafractional motion of the prostate during hypofractionated radiotherapy

PURPOSE

To report the characteristics of prostate motion as tracked by the stereoscopic X-ray images of the implanted fiducials during hypofractionated radiotherapy with CyberKnife.

METHODS AND MATERIALS

Twenty-one patients with prostate cancer who were treated with CyberKnife between January 2005 and September 2007 were selected for this retrospective study. The CyberKnife uses a stereoscopic X-ray system to obtain the position of the prostate target through the monitoring of implanted gold fiducial markers. If there is a significant deviation, the treatment is paused while the patient is repositioned by moving the couch. The deviations calculated from X-ray images acquired within the time interval between two consecutive couch motions constitute a data set.

RESULTS

Included in the analysis were 427 data sets and 4,439 time stamps of X-ray images. The mean duration for each data set was 697 sec. At 30 sec, a motion >2 mm exists in about 5% of data sets. The percentage is increased to 8%, 11%, and 14% at 60 sec, 90 sec, and 120 sec, respectively. A similar trend exists for other values of prostate motion.

CONCLUSIONS

With proper monitoring and intervention during treatment, the prostate shifts observed among patients can be kept within the tracking range of the CyberKnife. On average, a sampling rate of approximately 40 sec between consecutive X-rays is acceptable to ensure submillimeter tracking. However, there is significant movement variation among patients, and a higher sampling rate may be necessary in some patients.

A Monte Carlo Model for Independent Dose Verification in Serial Tomotherapy

Due to the very high complexity of IMRT treatment plans, it is imperative to perform dose verification, preferably before patient delivery. The aim of this project is to develop a Monte-Carlo-based model to verify the final dose distributions of plans developed using the Peacock system (CORVUS Treatment Planning System and MIMiC collimator). The system delivers radiation through arc therapy and uses sinogram files to determine the state of each of the multileaf collimator leaves. In-house software was developed using Matlab to decode the sinograms and create blocklets that are used as input in an MCSIM model of the MIMiC collimator attached to a Varian Clinac 600C. After validating the model, a prostate and head and neck case were simulated. The CORVUS-predicted dose distributions were compared with the Monte Carlo dose distributions. As expected, the results agreed very closely for the homogeneous case of the prostate but there were large discrepancies observed for the more heterogeneous head and neck case.

Is it beneficial to selectively boost high-risk tumor subvolumes? A comparison of selectively boosting high-risk tumor subvolumes versus homogeneous dose escalation of the entire tumor based on equivalent EUD plans

PURPOSE

To quantify and compare expected local tumor control and expected normal tissue toxicities between selective boosting IMRT and homogeneous dose escalation IMRT for the case of prostate cancer.

METHODS

Four different selective boosting scenarios and three different high-risk tumor subvolume geometries were designed to compare selective boosting and homogeneous dose escalation IMRT plans delivering the same equivalent uniform dose (EUD) to the entire PTV. For each scenario, differences in tumor control probability between both boosting strategies were calculated for the high-risk tumor subvolume and remaining low-risk PTV, and were visualized using voxel based iso-TCP maps. Differences in expected rectal and bladder complications were quantified using radiobiological indices (generalized EUD (gEUD) and normal tissue complication probability (NTCP)) as well as %-volumes.

RESULTS

For all investigated scenarios and high-risk tumor subvolume geometries, selective boosting IMRT improves expected TCP compared to homogeneous dose escalation IMRT, especially when lack of control of the high-risk tumor subvolume could be the cause for tumor recurrence. Employing, selective boosting IMRT significant increases in expected TCP can be achieved for the high-risk tumor subvolumes. The three conventional selective boosting IMRT strategies, employing physical dose objectives, did not show significant improvement in rectal and bladder sparing as compared to their counterpart homogeneous dose escalation plans. However, risk-adaptive optimization, utilizing radiobiological objective functions, resulted in reduction in NTCP for the rectum when compared to its corresponding homogeneous dose escalation plan.

CONCLUSIONS

Selective boosting is a more effective method than homogeneous dose escalation for achieving optimal treatment outcomes. Furthermore, risk-adaptive optimization increases the therapeutic ratio as compared to conventional selective boosting IMRT.

Patient-reported lower urinary tract symptoms, urinary incontinence, and quality of life after external beam radiotherapy for localized prostate cancer--15 years' follow-up. A comparison with age-matched controls

BACKGROUND

To prospectively examine the urinary toxicity and quality of life (QOL) in patients 15 years after external beam radiotherapy (EBRT) for localized prostate cancer (LPC) and compare the outcomes with results for age-matched controls.

MATERIAL AND METHODS

Urinary symptoms were assessed using the symptom-specific Prostate Cancer Symptom Scale (PCSS) questionnaire, and QOL was assessed with the European Organization for Research and Treatment of Cancer (EORTC)'s Quality of Life Questionnaire (QLQ-C30). Both questionnaires were sent to the surviving 41 patients(25%) and the PCSS questionnaire was sent to 69 age-matched controls for comparison.

RESULTS

The response rate was 71% in the patient group and 59% in the control group. Two patients and four controls were excluded due to other cancer diagnoses, resulting in a total of 27 patients and 37 controls for inclusion in the analyses. The mean age in both groups was 78 years. In the patient group, incontinence had increased between the 8-year (mean 0.6) and the 15-year follow-up (mean 2.1; p0.038). No other differences in urinary problems were seen between these two follow-ups. Increased incontinence, stress incontinence, and pain while urinating were reported by the patients in comparison with the controls at 15 years. Role function was worse in the patient group (mean 67.3) compared with the controls (mean 82.4; p0.046). The patients also reported more appetite loss, diarrhea, nausea/vomiting, and pain than the controls.

CONCLUSION

EBRT for LPC has divergent effects on urinary symptoms and QOL in comparison with age-matched controls. In our patient population, urinary incontinence increased between 8 and 15 years of follow-up. Otherwise, no differences in urinary symptoms were seen between 4 and 15 years. Incontinence, stress incontinence, and pain while urinating were increased after EBRT in comparison with the controls. Conventional EBRT did not result in a major deterioration in QOL 15 years after treatment.

[Radiotherapy for locally advanced prostate cancer]

Technical developments in radiation oncology have led to major improvements in the treatment of locally advanced prostate cancer. This article summarizes the publications on dose escalation, including the side effects. The effect of additional hormonal therapy and irradiation of the pelvic lymphatics is also discussed.