Volumetric modulated arc therapy for prostate cancer patients with hip prosthesis

Aim

To study the use of RapidArc techniques in the treatment of prostate cancer patients with hip prosthesis.

Background

An important aspect of treatment planning is to achieve dose homogeneity inside the planning target volume (PTV). Especially for those patients presenting with hip prosthesis, it becomes a challenging task to achieve dose uniformity inside the PTV.

Materials and methods

Five prostate patients presenting with hip prosthesis who had undergone radical radiotherapy were selected for this study. Depending on the composition of prosthesis, a predefined set of Hounsfield values were assigned to each study set. RapidArc plans were generated on an Eclipse treatment planning system. Two arcs that include clockwise and counter-clockwise arcs were used in all these cases. To avoid beams passing through the prosthesis, a simple structure was defined around it with 1 cm margin and a strict dose constraint applied to the block during VMAT optimization.

Results

The mean D2/D98 ratio of PTV for all the patients was 1.06 ± 0.01. The mean percentage rectum volume receiving 50 Gy, 60 Gy, 70 Gy and 75 Gy for all the patients were 33.1 ± 5.9, 21.7 ± 5.5, 13.8 ± 4.4 and 9.5 ± 3.0, respectively.

Conclusions

This study shows that using a double arc RapidArc technique is a simple and effective treatment method of treating prostate cancer in patients presenting with a hip prosthesis. The definition of a beam avoidance structure encompassing the prosthesis and applying strict dose constraints to it reduces the beam contribution to the prosthesis     

Volumetric modulated arc therapy in prostate cancer patients with metallic hip prostheses in a UK centre

AimThis study aimed to investigate whether IMRT using VMAT is a viable and safe solution in dose escalated RT in these patients.BackgroundAn increasing number of prostate cancer patients are elderly and have hip prostheses. These implants pose challenges in radiotherapy treatment planning. Although intensity modulated radiotherapy (IMRT) is commonly used, there is a lack of clinical studies documenting its efficacy and toxicities in this subgroup of patients.Materials and methodsThe data from 23 patients with hip prostheses and non-metastatic prostate cancer treated with VMAT (volumetric modulated arc therapy) between 2009 and 2011, were retrospectively analyzed. Baseline characteristics, treatment details and outcome data were collected on all patients. The median follow up was 40.9 months. MRI-CT image fusion was performed and the treatment plans were created using RapidArc™ (RA) techniques utilizing 1 or 2 arcs and 10 MV photon beams.Results96% of patients were treated with a dose of 72 Gy/32 fractions over 44 days. 21/23 plans met the PTV targets. The mean homogeneity index was 1.07. 20/23 plans met all OAR constraints (rectum, bladder). Two plans deviated from rectal constraints, four from bladder constraints; all were classed as minor deviations. One patient experienced late grade 3 genitourinary toxicity. Three other patients experienced late grade 2 or lower gastrointestinal toxicity. One patient had biochemical failure and one had a non-prostate cancer related death.ConclusionsVMAT provides an elegant solution to deliver dose escalated RT in patients with unilateral and bilateral hip replacements with minimal acute and late toxicities.     

Positive prostate biopsy following radiotherapy can predict metastasis-free survival in localized prostate cancer

Background/aim(s)To determine the impact of post-treatment biopsy results on 10-year metastasis-free survival (MFS), overall survival (OS) and cause-specific survival (CSS) in localized prostate cancer (PCa) patients treated with high-dose radiotherapy (RT).Materials/MethodsRetrospective analysis of 232 patients with T1c-T3bN0M0 PCa who underwent a prostate biopsy 24–36 months after high-dose RT. Biopsies were categorized as positive biopsy (PB) if H&E staining showed evidence of residual malignancy and negative biopsy (NB) if no malignant cells were present. Kaplan-Meier estimates of 10-year MFS, OS and CSS rates were calculated for each group and Cox proportional-hazards models were used to estimate the hazard ratios. The median follow-up was 124 months (range 26–267).ResultsSixty-two of 232 (26.7%) patients had post-treatment positive biopsies (PB). A positive post-treatment biopsy was significantly associated with a lower 10-year MFS (78.4% vs. 95.4%, p = 0.001, HR: 3.9, 95% CI: 1.8–8.3). Although patients with PB had worse outcomes that those with NB, we could not show a statistically significant difference in OS (81.0% vs. 87.9%, p = 0.282, HR: 1.3, 95% CI: 0.7–2.3) or CSS (96.2% vs. 99.4% (p = 0.201, HR. 2.4, 95% CI: 0.6–9.7). After multivariate analysis, the strongest predictor of MFS was the post-treatment biopsy status (p < 0.001, HR: 5.4, 95% CI 2.26–12.85) followed by Gleason score (p = 0.002, HR: 2.24, 95% CI 1.33–3.79).ConclusionA positive biopsy following RT can predict MFS in localized prostate cancer. These data highlight the relevance of achieving a local control and support the use of aggressive local therapeutic interventions for PCa.     

Implementation of intensity modulated radiotherapy for prostate cancer in a private radiotherapy service in Mexico

Intensity modulated radiation therapy (IMRT) allows physicians to deliver higher conformal doses to the tumour, while avoiding adjacent structures. As a result the probability of tumour control is higher and toxicity may be reduced. However, implementation of IMRT is highly complex and requires a rigorous quality assurance (QA) program both before and during treatment. The present article describes the process of implementing IMRT for localized prostate cancer in a radiation therapy department. In our experience, IMRT implementation requires careful planning due to the need to simultaneously implement specialized software, multifaceted QA programs, and training of the multidisciplinary team. Establishing standardized protocols and ensuring close collaboration between a multidisciplinary team is challenging but essential.     

Late toxicity for prostate cancer patients treated with hypofractionated helical tomotherapy

AimThe purpose of this study is to evaluate the long term tolerability of hypofractionated helical tomotherapy (HT) in localized prostate cancer patients.BackgroundPrevious hypofractionated schedules with conventional RT were associated with excessive toxicity, likely due to inadequate sophistication of treatment delivery. There are few data about late toxicity after HT.Materials and methodsWe evaluated 38 patients with primary adenocarcinoma of the prostate. There were 9 (24%), 15 (39%), and 14 (37%) patients with high, intermediate, and low risk, respectively. Patients were treated with hypofractionated HT from May 2008 to February 2011. Hypofractionation regimens included: 68.04 Gy at 2.52 Gy/fraction (N = 25; 66%), 70 Gy at 2.5 Gy/fraction (N = 4; 11%) and 70.2 Gy at 2.6 Gy/fraction (N = 9; 23%). Late genitourinary (GU) and gastrointestinal (GI) toxicity was scored using the Radiation Therapy Oncology Group scoring system.ResultsMedian age at diagnosis was 70 years (range 49–80) and median follow-up, 5.8 years. Late grade 1, 2 and 3 GI toxicity were 13%, 24%, and 2.6%, respectively. Late grade 1, 2, 3 GU toxicity were 29%, 21%, and 8%, respectively. Sexual toxicity was evaluated in 19 patients to be grade 1, 2 in 11% and grade 3 in 16%. Multivariate analysis showed that patients with higher values of rectum V50 associated with late GI toxicity (P = 0.025). Patients with PSA ≤8 (P = 0.048) or comorbidities (P = 0.013) at diagnosis were associated with higher late GU toxicity. Additionally, PSA ≤8 also associated with moderate (grade ≥2) late GU toxicity in the multivariate analysis (P = 0.028).ConclusionsHypofractionated HT can be delivered safely with limited rates of moderate and severe late toxicity. The proportion of the rectum that receives a moderate and high dose, having comorbidities, and PSA at diagnosis seem to associate with long term toxicity.     

Treatment outcomes and late toxicities of intensity-modulated radiation therapy for 1091 Japanese patients with localized prostate cancer

Aim

This study aimed to evaluate the treatment result of intensity-modulated radiation therapy (IMRT) in a large number of Japanese patients with prostate cancer.

Machine log file-based dose verification using novel iterative CBCT reconstruction algorithm in commercial software during volumetric modulated arc therapy for prostate cancer patients

PurposeTo evaluate the utility of the use of iterative cone-beam computed tomography (CBCT) for machine log file-based dose verification during volumetric modulated arc therapy (VMAT) for prostate cancer patients.MethodsAll CBCT acquisition data were used to reconstruct images with the Feldkamp-Davis-Kress algorithm (FDK-CBCT) and the novel iterative algorithm (iCBCT). The Hounsfield unit (HU)-electron density curves for CBCT images were created using the Advanced Electron Density Phantom. The I’mRT and anthropomorphic phantoms were irradiated with VMAT after CBCT registration. Subsequently, fourteen prostate cancer patients received VMAT after CBCT registration. Machine log files and both CBCT images were exported to the PerFRACTION software, and a 3D patient dose was reconstructed. Mean dose for planning target volume (PTV), the bladder, and rectum and the 3D gamma analysis were evaluated.ResultsFor the phantom studies, the variation of HU values was observed at the central position surrounding the bones in FDK-CBCT. There were almost no changes in the difference of doses at the isocenter between measurement and reconstructed dose for planning CT (pCT), FDK-CBCT, and iCBCT. Mean dose differences of PTV, rectum, and bladder between iCBCT and pCT were approximately 2% lower than those between FDK-CBCT and pCT. For the clinical study, average gamma analysis for 2%/2 mm was 98.22% ± 1.07 and 98.81% ± 1.25% in FDK-CBCT and iCBCT, respectively.ConclusionsA similar machine log file-based dose verification accuracy is obtained for FDK-CBCT and iCBCT during VMAT for prostate cancer patients.     

Volumetric image-guided conformal radiotherapy for localized prostate cancer: Analysis of dosimetric and clinical factors affecting acute and late toxicity

Aim

To identify factors influencing toxicity in patients affected by localized prostate cancer treated with conformal image-guided radiotherapy.

Dosimetric comparison of RapidPlan and manually optimized plans in volumetric modulated arc therapy for prostate cancer

PurposeThis study evaluated whether RapidPlan based plans (RP plans) created by a single optimization, are usable in volumetric modulated arc therapy (VMAT) for patients with prostate cancer.MethodsWe used 51 previously administered VMAT plans to train a RP model. Thirty RP plans were created by a single optimization without planner intervention during optimization. Differences between RP plans and clinical manual optimization (CMO) plans created by an experienced planner for the same patients were analyzed (Wilcoxon tests) in terms of homogeneity index (HI), conformation number (CN), D_95%, and D_2% to planning target volume (PTV), mean dose, V_50Gy, V_70Gy, V_75Gy, and V_78Gy to rectum and bladder, monitor unit (MU), and multi-leaf collimator (MLC) sequence complexity.ResultsRP and CMO values for PTV D_95%, PTV D_2%, HI, and CN were significantly similar (p < 0.05 for all). RP mean dose, V_50Gy, and V_70Gy to rectum were superior or comparable to CMO values; RP V_75Gy and V_78Gy were higher than in CMO plans (p < 0.05). RP bladder dose-volume parameter values (except V_78Gy) were lower than in CMO plans (p < 0.05). MU values were RP: 730 ± 55 MU and CMO: 580 ± 37 MU (p < 0.05); and MLC sequence complexity scores were RP: 0.25 ± 0.02 and CMO: 0.35 ± 0.03 (p < 0.05).ConclusionsRP plans created by a single optimization were clinically acceptable in VMAT for patient with prostate cancer. Our simple model could reduce optimization time, independently of planner’s skill and knowledge.     

SIMBOSPROST: Prevalence of metabolic syndrome and osteoporosis in prostate cancer patients treated with radiotherapy and androgen deprivation therapy: A multicentre,cross-sectional study

AimTo assess the prevalence of metabolic syndrome (MetS) and osteoporosis in patients with prostate cancer (PCa) treated with radical radiotherapy (RT) with or without androgen deprivation therapy (ADT).BackgroundWorldwide, the prevalence of MetS is estimated to range from 20% to 25% of the adult population. However, prevalence rates are much higher in PCa patients (pts) who undergo ADT.Materials and methodsMulticentre cross-sectional study of 270 pts in Spain with PCa. Patients were divided into 3 groups based on the duration of ADT (6, 12–18, ≥24 months) and compared to a control group without ADT. MetS was defined according to NCEP ATP III criteria. Osteoporosis was assessed by DEXA.ResultsA total of 270 pts, treated from November 2011 to October 2012, were included. Of these, 122 pts (47%) fulfilled the criteria for MetS. The median age of this group was significantly higher (71.3 vs. 69.38 years, p = 0.028). MetS prevalence was 50% in the control group. In pts who received ADT, prevalence was 44.8% after 6 months of ADT, 45.3% after 12–18 months, and 50% after ≥24 months (pns). Most pts (168/270; 62%) underwent DEXA. Of those tested, 78 (46.4%) had osteopenia and only 11 (6.5%) had osteoporosis.ConclusionsThe prevalence of MetS in pts with PCa treated with radical RT was higher (47%) than in the general population. However, there were no significant differences in the duration of ADT administration. The prevalence of osteoporosis was low. These findings suggest that the prevalence of MetS in PCa patients may be higher than previously reported.     

Displacements of fiducial markers in patients with prostate cancer treated with image guided radiotherapy: A single-institution descriptive study

Aim

To describe daily displacements when using fiducial markers as surrogates for the target volume in patients with prostate cancer treated with IGRT.

Background

The higher grade of conformity achieved with the use of modern radiation technologies in prostate cancer can increase the risk of geographical miss; therefore, an associated protocol of IGRT is recommended.

Materials and methods

A single-institution, retrospective, consecutive study was designed. 128 prostate cancer patients treated with daily on-line IGRT based on 2D kV orthogonal images were included. Daily displacement of the fiducial markers was considered as the difference between the position of the patient when using skin tattoos and the position after being relocated using fiducial markers. Measures of central tendency and dispersion were used to describe fiducial displacements.

Results

The implant itself took a mean time of 15 min. We did not detect any complications derived from the implant. 4296 sets of orthogonal images were identified, 128 sets of images corresponding to treatment initiation were excluded; 91 (2.1%) sets of images were excluded from the analysis after having identified that these images contained extreme outlier values. If IGRT had not been performed 25%, 10% or 5% of the treatments would have had displacements superior to 4, 7 or 9 mm respectively in any axis.

Conclusions

Image guidance is required when using highly conformal techniques; otherwise, at least 10% of daily treatments could have significant displacements. IGRT based on fiducial markers, with 2D kV orthogonal images is a convenient and fast method for performing image guidance.     

Techniques for adaptive prostate radiotherapy

Variations in the position and shape of the prostate make accurate setup and treatment challenging. Adaptive radiation therapy (ART) techniques seek to alter the treatment plan, at one or more points throughout the treatment course, in response to changes in patient anatomy observed between planning and pre-treatment images. This article reviews existing and developing ART techniques for prostate cancer along with an overview of supporting in-room imaging technologies. Challenges to the clinical implementation of adaptive radiotherapy are also discussed.     

Assessment of monitor unit limiting strategy using volumetric modulated arc therapy for cancer of hypopharynx

PurposeTo quantify relative merit of MU deprived plans against freely optimized plans in terms of plan quality and report changes induced by progressive resolution optimizer algorithm (PRO3) to the dynamic parameters of RapidArc.Materials and methodsTen cases of carcinoma hypopharynx were retrospectively planned in three phases without using MU tool. Replicas of these baseline plans were reoptimized using “Intermediate dose” feature and “MU tool” to reduce MUs by 20%, 35%, and 50%. Overall quality indices for target and OAR, integral dose, dose-volume spread were assessed. All plans were appraised for changes induced in RapidArc dynamic parameters and pre-treatment quality assurance (QA).ResultsWith increasing MU reduction strength (MURS), MU/Gy values reduced, for all phases with an overall range of 8.6–34.7%; mean dose rate decreased among plans of each phase, phase3 plans recorded greater reductions. MURS20% showed good trade-off between MUs and plan quality. Dose-volume spread below 5 Gy was higher for baseline plans while lower between 20 and 35 Gy. Integral dose was lower for MURS0%, not exceeding 1.0%, compared against restrained plans. Mean leaf aperture and control point areas increased systematically, correlated negatively with increasing MURS. Absolute delta dose rate variations were least for MURS0%. MU deprived plans exhibited GAI (>93%), better than MURS0% plans.ConclusionBaseline plans are superior to MU restrained plans. However, MURS20% offers equivalent and acceptable plan quality with mileage of MUs, improved GAI for complex cases. MU tool may be adopted to tailor treatment plans using PRO3.     

Predicting toxicity in radiotherapy for prostate cancer

This comprehensive review addresses most organs at risk involved in planning optimization for prostate cancer. It can be considered an update of a previous educational review that was published in 2009 (Fiorino et al., 2009).The literature was reviewed based on PubMed and MEDLINE database searches (from January 2009 up to September 2015), including papers in press; for each section/subsection, key title words were used and possibly combined with other more general key-words (such as radiotherapy, dose-volume effects, NTCP, DVH, and predictive model). Publications generally dealing with toxicity without any association with dose–volume effects or correlations with clinical risk factors were disregarded, being outside the aim of the review.A focus was on external beam radiotherapy, including post-prostatectomy, with conventional fractionation or moderate hypofractionation (<4 Gy/fraction); extreme hypofractionation is the topic of another paper in this special issue. Gastrointestinal and urinary toxicity are the most investigated endpoints, with quantitative data published in the last 5 years suggesting both a dose–response relationship and the existence of a number of clinical/patient related risk factors acting as dose–response modifiers. Some results on erectile dysfunction, bowel toxicity and hematological toxicity are also presented.     

Survival and clinical metastases among prostate cancer patients treated with androgen deprivation therapy in Sweden

ObjectivesTo examine the incidence of metastases and clinical course of prostate cancer patients who are without confirmed metastasis when initiating androgen deprivation therapy (ADT).MethodsRetrospective cohort study conducted using electronic medical records from Swedish outpatient urology clinics linked to national mandatory registries to capture medical and demographic data. Prostate cancer patients initiating ADT between 2000 and 2010 were followed from initiation of ADT to metastasis, death, and/or end of follow-up.ResultsThe 5-year cumulative incidence (CI) of metastasis was 18%. Survival was 60% after 5 years; results were similar for bone metastasis-free survival. The 5-year CI of castration-resistant prostate cancer (CRPC) was 50% and the median survival from CRPC development was 2.7 years. Serum prostate-specific antigen (PSA) levels and PSA doubling time were strong predictors of bone metastasis, any metastasis, and death.ConclusionThis study provides understanding of the clinical course of prostate cancer patients without confirmed metastasis treated with ADT in Sweden. Greater PSA values and shorter PSA doubling time (particularly ≤ 6 months) were associated with increased risk of bone metastasis, any metastasis, and death.     

Empirical estimation of beam-on time for prostate cancer patients treated on Tomotherapy

Background and aim

This study proposed a method to estimate the beam-on time for prostate cancer patients treated on Tomotherapy when FW (field width), PF (pitch factor), modulation factor (MF) and treatment length (TL) were given.

Material and methods

The study was divided into two parts: building and verifying the model. To build a model, 160 treatment plans were created for 10 patients. The plans differed in combination of FW, PF and MF. For all plans a graph of beam-on time as a function of TL was created and a linear trend function was fitted. Equation for each trend line was determined and used in a correlation model. Finally, 62 plans verified the treatment time computation model – the real execution time was compared with our estimation and irradiation time calculated based on the equation provided by the manufacturer.

Results

A linear trend function was drawn and the coefficient of determination R² and the Pearson correlation coefficient r were calculated for each of the 8 trend lines corresponding to the adequate treatment plan. An equation to correct the model was determined to estimate more accurately the beam-on time for different MFs. From 62 verification treatment plans, only 5 disagreed by more than 60 s with the real time from the HT software. Whereas, for the equation provided by the manufacturer the discrepancy was observed in 16 cases.

Conclusions

Our study showed that the model can well predict the treatment time for a given TL, MF, FW and it can be used in clinical practice.     

Significant impact on the oncologic outcomes with intensity modulated radiotherapy and conformational radiotherapy over conventional radiotherapy in cervix cancer patients treated with radiotherapy

ObjectiveWe designed a retrospective cohort of women with cervix cancer treated by radiation therapy with an extended follow-up to evaluate if the incorporation of modern radiation techniques was a prognostic factor.Material and methodsWe studied a cohort of patients with cervix cancer FIGO stage I-IVa treated in the last fifteen years. Patients were treated with radiotherapy alone (RT) or chemoradiation alone (CRT) using conventional radiotherapy (2DRT), conformational radiotherapy (3DRT), or intensity-modulated radiotherapy (IMRT) followed by high dose rate brachytherapy. Univariate and multivariate analysis was conducted to identify significant prognostic factors (p < 0.05).Results228 patients with cervix cancer were included. The treatment groups were CRT (64.8%), and RT (34.2%), with 31.6% submitted to 2DRT and 68.4% to IMRT/3DRT. The median follow-up was 6.3 years, the OS in 5 years according to the treatment groups was 48% for CRT, and 27.8% for RT (p < 0.001). The early-stage I-IIa (p = 0.001), CRT, and IMRT/3DRT were significant factors for better overall survival (OS) in the multivariate analysis. For the cancer-specific survival (CSS), chemoradiation, age <60 years, and IMRT/3DRT were significant. Treatment with IMRT/3DRT was the only prognostic factor associated with event-free survival (EFS).ConclusionIn a long-term follow-up, chemoradiation, early-clinical stage, and age <60 years were significant factors associated with better OS and CSS at 5 and 8 years. The incorporation of new radiation techniques, such as IMRT/3DRT, over time has a significant impact on all endpoints (EFS, OS, and CSS) of this cohort. These outcomes are useful to decide about the radiation technique to achieve satisfactory oncological results outside a clinical trial.     

Incidence of radiation toxicity in cervical cancer and endometrial cancer patients treated with radiotherapy alone versus adjuvant radiotherapy

AimThe study was made to evaluate early and late toxicity in a diversified group of patients receiving definitive or adjuvant radiotherapy in terms of clinical diagnosis and treatment methods.BackgroundRadiotherapy is a standard way of treatment in cervical and endometrial cancer patients, both as definitive and adjuvant therapy. But every radiation treatment may be involved with toxicity.Materials and methodsA detailed analysis was performed of 263 patients with gynaecological cancer treated with definitive (90 patients with cervical cancer received radiochemotherapy or radiotherapy exclusively) and adjuvant radiotherapy (38 with cervical and 135 with endometrial cancer).ResultsAcute reactions were found in 51.3% and late reactions were found in 14.8% of patients. It was stated that early (p < 0.007) and late (p < 0.003) post radiation reaction appear more frequently in women treated with definitive than adjuvant radiotherapy. The analysis of the whole group revealed higher rate of toxicity, both early and late, in the gastrointestinal tract than in the urinary system (p < 0.004). Comparing the subgroups, it was found that intestinal reactions occurred more frequently in the definitive radiotherapy group than in the adjuvant one.The occurrence of side effects was associated with the prolongation of total irradiation time due to necessary interruptions of radiotherapy. The comparison of the subgroups showed that interruptions occurred more frequently in patients receiving definitive rather than adjuvant radiotherapy (17.7–2.9%).ConclusionsDefinitive radiotherapy compared with adjuvant treatment may by associated with higher percentage of side effects caused by dose of therapy and correlation with chemotherapy.