Local Resection and Brachytherapy for Primary Orbital Rhabdomyosarcoma: Outcome and Failure Pattern Analysis.

PURPOSE: Survival in patients with orbital rhabdomyosarcoma (RMS) is excellent. Therefore, new local treatment modalities, such as brachytherapy, have been developed to minimize adverse events. Since 1990, patients with orbital RMS and a residual tumor after induction chemotherapy were eligible for resection and brachytherapy. Otherwise patients received external beam radiotherapy. In this study, the authors describe the outcome for 20 patients with primary orbital RMS. The aim was to assess risk factors for treatment failure in this single center cohort. METHODS: In this retrospective cohort study, the authors reviewed imaging studies, surgery reports, histology reports, and radiotherapy plans in a multidisciplinary setting. The authors included 20 consecutive patients with orbital RMS, treated between 1990 and 2007, (median age: 7.4 years, range: 0.7-16.1; median follow up: 11.5 years). RESULTS: After induction chemotherapy, 12 patients were treated with surgery and brachytherapy, 2 with external beam radiotherapy, and in 5 patients who achieved complete remission, local treatment was withheld. In 1 patient, brachytherapy was incorrectly withheld after delayed surgery. Seven patients relapsed (no local treatment, N = 2; surgery and brachytherapy, N = 2; external beam radiotherapy, N = 2; surgery only, N = 1). The authors found no patient, tumor, or treatment characteristics that predisposed for treatment failure. Ten-year-overall survival and event-free survival were 89% and 65%, respectively. CONCLUSIONS: Overall survival in this cohort of orbital RMS patients was good, including surgery and brachytherapy as treatment modality for orbital RMS resulted in an effective local treatment approach with fewer adverse events than external beam radiotherapy. The authors could not identify factors predisposing for treatment failure.

Deviations from the planned dose during 48 hours of stepping source prostate brachytherapy caused by anatomical variations.

BACKGROUND AND PURPOSE: To determine the uncertainties in planned dose associated with catheter and organ movement during 48 hours of stepping source prostate brachytherapy. MATERIAL AND METHODS: Pulsed-dose rate (PDR) prostate brachytherapy as a boost is given in 24 pulses every 2 hours, making the total treatment last 48 hours. The entire treatment is based on one plan, created on the planning CT (CT1). Two follow-up CTs (CT2 and CT3) were acquired; halfway through the treatment and at the end of treatment. On these repeat scans the catheters were reconstructed and PTV and OARs were delineated. The original treatment plan was calculated on the repeat CTs. Target coverage V(100%), D(90), dose to 2cm(3) (D2cm(3)) of the rectum and bladder and dose to 0.1cm(3) of the urethra were recorded from the recalculated DVHs. RESULTS: On the two repeat CTs the V100% decreased -1.5% and -2.3% as compared to the planning CT. For the rectum D2cm(3), the average increase was 14.8% (CT1-CT2) and 17.3% (CT1-CT3). Increase in bladder D2cm(3) was on average 23.1% (CT1-CT2) and 24.8% (CT1-CT3). For the urethra D0.1cm(3) an average decrease of -2% (CT1-CT2) and -3.2% (CT2-CT3) was observed. CONCLUSIONS: Changes in target coverage during treatment were small and considered clinically irrelevant. However, an overall increase in dose to the OARs was found as compared to the planned dose, which should be taken into account during treatment planning.

Improved tumour control probability with MRI-based prostate brachytherapy treatment planning.

BACKGROUND: Due to improved visibility on MRI, contouring of the prostate is improved compared to CT. The aim of this study was to quantify the benefits of using MRI for treatment planning as compared to CT-based planning for temporary implant prostate brachytherapy. MATERIAL AND METHODS: CT and MRI image data of 13 patients were used to delineate the prostate and organs at risk (OARs) and to reconstruct the implanted catheters (typically 12). An experienced treatment planner created plans on the CT-based structure sets (CT-plan) and on the MRI-based structure sets (MRI-plan). Then, active dwell-positions and weights of the CT-plans were transferred to the MRI-based structure sets (CT-plan(MRI-contours)) and resulting dosimetric parameters and tumour control probabilities (TCPs) were studied. RESULTS: For the CT-plan(MRI-contours) a statistically significant lower target coverage was detected: mean V100 was 95.1% as opposed to 98.3% for the original plans (p < 0.01). Planning on CT caused cold-spots that influence the TCP. MRI-based planning improved the TCPs by 6-10%, depending on the parameters of the radiobiological model used for TCP calculation. Basing the treatment plan on either CT- or MRI-delineations does not influence plan quality. CONCLUSION: Evaluation of CT-based treatment planning by transferring the plan to MRI reveals underdosage of the prostate, especially at the base side. Planning on MRI can prevent cold-spots in the tumour and improves the TCP.

Development of late toxicity and International Prostate Symptom Score resolution after external-beam radiotherapy combined with pulsed dose rate brachytherapy for prostate cancer.

PURPOSE: To investigate the development of gastrointestinal (GI) toxicity, genitourinary (GU) toxicity, erectile dysfunction, and International Prostate Symptom Score (IPSS) resolution in a cohort of patients treated with external-beam radiotherapy (EBRT) followed by a brachytherapy pulsed dose rate (PDR) boost. METHODS AND MATERIALS: Between 2002 and 2008, 110 patients were treated with 46-Gy EBRT followed by PDR brachytherapy (24.96-28.80 Gy). The investigated outcome variables, GI toxicity, GU toxicity, erectile dysfunction, and IPSS were prospectively scored at several time points during follow-up. Association between time (as continuous and categorical variable) and the outcome variables was assessed using generalized linear models. RESULTS: No statistically significant association was found between time (continuous) and GI toxicity (odds ratio [OR], 0.97; 95% confidence interval [CI], 0.89-1.06), GU toxicity (OR, 0.97; 95% CI, 0.91-1.03), erectile dysfunction (OR, 1.06; 95% CI, 0.99-1.11), and IPSS (-0.11; 95% CI, -0.41-0.20). Also, no statistically significant association was found between these variables and time as a categorical variable. GU toxicity was associated with IPSS resolution (OR, 1.16; 95% CI, 1.09-1.24). Posttreatment IPSS was associated with pretreatment IPSS (0.52; 95% CI, 0.25-0.79). CONCLUSIONS: No accumulation of high-grade toxicity over time could be established for a group of patients treated with EBRT and PDR brachytherapy for prostate cancer, probably because high-grade late toxicity resolves with time. Also, differences in IPSS values among patients are smaller after treatment than before treatment.

Treatment results of PDR brachytherapy combined with external beam radiotherapy in 106 patients with intermediate- to high-risk prostate cancer.

PURPOSE: To evaluate treatment outcome of pulsed dose-rate brachytherapy (PDR) combined with external-beam radiotherapy (EBRT) for the treatment of prostate cancer. METHODS AND MATERIALS: Between 2002 and 2007, 106 patients were treated by EBRT combined with PDR and followed prospectively. Two, 38, and 66 patients were classified as low-, intermediate-, and high-risk disease respectively according to the National Comprehensive Cancer Network criteria. EBRT dose was 46 Gy in 2.0-Gy fractions. PDR dose was increased stepwise from 24.96 to 28.80 Gy. Biochemical disease free survival and overall survival were determined by the Kaplan-Meier method. Cumulative incidence of late gastrointestinal (GI) and genitourinary (GU) toxicity were scored, according to the Common Terminology Criteria for Adverse Events. RESULTS: The 3- and 5-year biochemical nonevidence of disease (bNED) were 92.8% (95% confidence interval [CI], 87.1-98.5) and 89.5% (95% CI, 85.2-93.8), respectively. Overall survival at 3 and 5 years was 99% (95% CI, 96-100) and 96% (95% CI, 90-100), respectively. The 3- and 5-year Grade 2 GI toxicity was 5.3% (95% CI, 0-10.6) and 12.0% (95% CI, 1.4-22.6), respectively. No Grade 3 or higher GI toxicity was observed. The 3- and 5-year Grade 2 or higher GU toxicity was 18.7% (95% CI, 10.3-27.1) and 26.9% (95% CI, 15.1-38.7), respectively. CONCLUSION: Results on tumor control and late toxicity of EBRT combined with PDR are good and comparable to results obtained with EBRT combined with high-dose-rate brachytherapy for the treatment of prostate cancer.

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.