Stereotactic Body Radiotherapy for the Treatment of Renal Tumors

The purpose of this study was to evaluate the response of actively growing renal masses to stereotactic body radiation therapy (SBRT). We retrospectively reviewed our institutional review board–approved kidney database and identified 4 patients who underwent SBRT, 15 Gy dose, for their rapidly growing renal masses. Three patients had a decreased tumor size after radiation treatment by 20.8%, 38.1%, and 20%. The other patient had a size gain of 5.6%. This patient maintained a similar tumor growth rate before and after SBRT. Mean follow-up time was 13.8 months. SBRT represents an effective management option in select patients with larger rapidly growing kidney masses.

High-dose interleukin-2 therapy for metastatic renal cell carcinoma: a contemporary experience

OBJECTIVE

To present our experience of high-dose interleukin-2 (HDIL-2) in a high-volume National Cancer Institute-designated center for patients with metastatic renal cell carcinoma (mRCC).

METHODS

Patients with mRCC who received HDIL-2 monotherapy as a first- or second-line therapy during 2004-2011 were identified. Demographics, pathologic variables, renal function, time until the start of HDIL-2 therapy, number of cycles (1-3), responses (complete response, partial response, stable disease, and progressive disease), and primary renal cell carcinoma treatment were analyzed. Progression-free survival and overall survival (OS) were determined.

RESULTS

Of 906 patients in the kidney cancer database, 91 patients with mRCC were treated with HDIL-2 and 18 patients (20.5%) underwent prior cytoreductive nephrectomy. Median age was 51 years, and 73.9% were men. Median follow-up was 45 months. Pretreatment renal function impairment led to more treatment cycles (2-3) than in those with adequate initial kidney function (92.3% vs 50.6%, respectively; P = .002). Lower tumor stage correlated with a better response (P = .023) and with longer time from diagnosis to initiation of HDIL-2 (P = .011). Complications included hypotension (67.4%), renal impairment (63%), impaired liver function (42.4%), and thrombocytopenia (31.5%). Four patients (4.5%) had a complete response, 10 (11.4%) had a partial response, and 28 (31.8%) had a stable disease. Median progression-free survival and OS were 8.6 and 35.5 months, respectively. The estimated 2-year OS rate was 60.6%.

CONCLUSION

Incorporating HDIL-2 therapy in the treatment strategies for mRCC added to the patients' survival in this series. HDIL-2 therapy is well tolerated in patients with pre-existing renal impairment with no long-term renal toxicity.

Health-related quality of life outcomes after robot-assisted and open radical cystectomy using a validated bladder-specific instrument: a multi-institutional study

OBJECTIVE

To evaluate health-related quality of life (HRQL) using validated bladder-specific Bladder Cancer Index (BCI) and European Organization for Research and Treatment of Cancer Body Image scale (BIS) between open radical cystectomy (ORC) and robot-assisted radical cystectomy (RARC).

METHODS

This was a retrospective case series of all patients who underwent radical cystectomy. Patients were grouped based on surgical approach (open vs robot assisted) and diversion technique (extracorporeal vs intracorporeal). Patients completed BCI and BIS preoperatively and at standardized postoperative intervals (at least 2). The primary exposure variable was surgical approach. The primary outcome measure was difference in interval and baseline BCI and BIS scores in each group. The Fisher exact, Wilcoxon rank-sum, and Kruskal-Wallis tests were used for comparisons.

RESULTS

Eighty-two and 100 patients underwent RARC and ORC, respectively. Compared with RARC, more patients undergoing ORC had an American Society of Anesthesiology score≥3 (66% vs 45.1% RARC; P=.007) and shorter median operative time (350 vs 380 minutes; P=.009). Baseline urinary, bowel, sexual function, and body image were not different between both the groups (P=1.0). Longitudinal postoperative analysis revealed better sexual function in ORC group (P=.047), with no significant differences between both the groups in the other 3 domains (P=.11, .58, and .93). Comparisons regarding diversion techniques showed similar findings in baseline and postoperative HRQL data, with no significant differences in the HRQL and body image domains.

CONCLUSION

RARC has comparable HRQL outcomes to ORC using validated BCI and BIS. The diversion technique used does not seem to affect patients' quality of life.

Deprivation and food access and balance in Saskatoon, Saskatchewan

Introduction

We explored food access and balance in Saskatoon, Saskatchewan, Canada in relation to material and social deprivation.

Methods

We mapped the location of all large supermarkets and fast food retailers in Saskatoon. Supermarket accessibility index scores and food balance scores were compared to material and social deprivation indexes to determine significant associations.

Results

Our results indicate that the poorest access to supermarkets occurred in areas west of the South Saskatchewan River and also in suburban areas around the perimeter of the city. Areas west of the river are some of the most deprived areas in the city. Saskatoon's mean food balance ratio of 2.3 indicates that access favours fast food. However, we did not find a clear pattern or clear socio-economic gradient for most measures.

Conclusion

This study highlights the importance of contextual studies of food access. This study also highlighted a number of other issues that should be explored in the Saskatoon context such as individual-level food consumption patterns, mobility, temporal dimensions of food access and economic access as well as interventions that could improve food access in the city.

Deprivation and food access and balance in Saskatoon, Saskatchewan

INTRODUCTION

We explored food access and balance in Saskatoon, Saskatchewan, Canada in relation to material and social deprivation.

METHODS

We mapped the location of all large supermarkets and fast food retailers in Saskatoon. Supermarket accessibility index scores and food balance scores were compared to material and social deprivation indexes to determine significant associations.

RESULTS

Our results indicate that the poorest access to supermarkets occurred in areas west of the South Saskatchewan River and also in suburban areas around the perimeter of the city. Areas west of the river are some of the most deprived areas in the city. Saskatoon's mean food balance ratio of 2.3 indicates that access favours fast food. However, we did not find a clear pattern or clear socio-economic gradient for most measures.

CONCLUSION

This study highlights the importance of contextual studies of food access. This study also highlighted a number of other issues that should be explored in the Saskatoon context such as individual-level food consumption patterns, mobility, temporal dimensions of food access and economic access as well as interventions that could improve food access in the city.

High-dose interleukin-2 therapy for metastatic renal cell carcinoma: A contemporary experience

e15604

Background: Despite recent advances in targeted treatment options, high dose interleukin-2 (HDIL-2) remains an important therapeutic option for metastatic renal cell carcinoma (mRCC). We present a contemporary experience of HDIL-2 in a high-volume, National Cancer Institute (NCI)-designated cancer center. Methods: Patients with mRCC who received HDIL-2 monotherapy as a first- or second-line therapy during 2004-2011 were identified. Patients’ demographics, pathologic variables, renal function, time until start of HDIL-2 therapy, number of cycles given (1-3), best responses (complete response; CR, partial response; PR, stable disease; SD, and progressive disease; PD), and primary RCC treatment were analyzed. Progression free survival (PFS) and overall survival (OS) were determined. Results: Of 176 mRCC patients, 91 patients were treated with HDIL-2 (59 as a primary treatment). Median age was 51 years and 73.9% were males. Median Follow-up was 44.9 months. Majority (92%) of tumors showed clear cell histology, and 14.8% had impaired renal function (creatinine >1.5 mg/dL) prior to treatment. Patients with impaired initial renal function were more likely to get more treatment cycles (2-3) than those with adequate initial kidney function (92.3% vs.50.6%, respectively; p=0.002). Eighteen (20.5%) patients underwent cytoreductive nephrectomy. Lower tumor stage at diagnosis correlated with better treatment response (p=0.023), but with longer time from diagnosis to initiation of HDIL-2 (p=0.011). Prominent therapy complications included hypotension (67.4%), renal impairment (63%), impaired liver function (42.4%), and thrombocytopenia (31.5%). None needed hemodialysis for IL-2 induced renal toxicity, and all regained their pre-treatment baseline kidney functions after therapy. Four patients (4.5%) had CR, 11.4% had PR, and 31.8% had SD. Median PFS and OS were 8.6 and 35.5 months, respectively. Estimated 2-year OS rate was 60.6%. Conclusions: Incorporating HDIL-2 therapy in treatment strategies of patients with mRCC added to the patients’ survival in this contemporary series. HDIL-2 therapy appears to be well tolerated in patients with preexisting renal impairment with no long term renal toxicity.

Abstract WP47: Flow Phantom for the Validation and Quantitative Analysis of Computed Tomography Perfusion

Objective: We create a flow phantom using a simple brain model with well-defined flow behavior. This allows for the validation of CT perfusion (CTP), as CTP data can be compared with theoretical calculations and gold standard flow meter values. Our approach offers a calibration system for existing CTP scanners, facilitating the selection of optimal data processing algorithms and parameter settings.

Methods: The phantom was built using 37 parallel glass capillary tubes of internal diameter 1.0 mm fixed with epoxy. Saline was pumped into the inlet portion of a Y-shaped tubing system with one inlet and two outlets. One Y outlet led to the phantom, which was in series with a flow meter. The other outlet flowed to a waste container. A contrast bolus was introduced at the Y inlet and perfusion imaging was performed with a Toshiba 320 slice Aquilion One scanner. Phantom flow rates of 3, 5, 7.5 and 20 mL/min were used. Time activity curves (TACs) were calculated by averaging along various phantom segments.

Results: CBV could be accurately recovered for all flow levels but 3 mL/min. MTT values were slightly higher than expected. Compared to TACs at the base of the Y, TACS just prior to the phantom showed significant dispersion. MTT measured across the phantom for length of 4.1 cm (i.e. internal volume 1 mL) with a flow meter rate of 20 mL/min was 0.066 min, whereas 0.05 min was expected. However, the same measurement for a flow of 3 mL/min had an MTT of 0.32 min, close to the expected value of 0.33 min.

Conclusions: We have developed a robust system for the analysis of CTP. CBV was accurate provided sufficient scan duration. MTT values were mildly exaggerated due to dispersion of the contrast bolus. This is analogous to measuring an early arterial TAC, such as the carotid TAC, when tissue segments are fed by smaller branches. This dispersion causes a lower bound for MTT, an effect that is greater at higher flows. Our system has the potential for the calibration and optimization of existing commercial CTP devices.

Abstract TMP14: Masked Smoothing for Computed Tomography Perfusion Imaging

Objective: CT perfusion imaging is characterized by a high contrast ratio between different structure types. This facilitates the segmentation of an image into different classes, such as tissue and vasculature. However, grey and white matter tissue regions have relatively low values and can suffer from poor signal to noise ratios. While smoothing can improve the image quality of brain parenchyma, the inclusion of high contrast vascular voxels skews the dataset. It is thus desirable to smooth the tissue voxels independently from other voxel types, as has been implemented previously using mean filters with small kernel sizes. Bilateral filters have also been proposed, allowing a varying influence of neighboring voxels based on the similarity of the voxel’s intensity. These filters are orders of magnitude slower, however, as the smoothing kernel is not directly separable. A separable kernel can be applied to an image volume as 3 implementations of a 1D filter. A kernel of size 50x50x50, for example, is applied to a volume with 3x50 (150) multiplications per voxel if it is separable and 50^3 (125,000) if it is not. Our approach, which applies smoothing to tissue voxels without including neighboring vessel voxels in the kernel, can be calculated by dividing the results of just two applications of a separable kernel.

Methods: We compare our Masked Smoothing method to alternative Gaussian smoothing approaches using an unaltered image and an image where vascular voxels have been set to zero. The base image size is 512x512x320x19.

Results: Using simulations we demonstrate that Masked Smoothing does not bias the underlying tissue value, whereas the other smoothing methods cause significant bias. Furthermore, using actual CT perfusion data, we demonstrate a significant difference in the calculated cerebral blood flow and cerebral blood volume based on the smoothing method used.

Conclusions: Given the enormous datasets inherent to CT perfusion and the need for rapid clinical evaluation, it is crucial to develop a smoothing method that prevents the bias of tissue values from neighboring vessels and executes rapidly. Our novel smoothing method achieves both goals.

Disulphide-coupled protein folding pathways

Protein folding pathways that involve disulphide bond formation can be determined in great detail. Those of bovine pancreatic trypsin inhibitor, alpha-lactalbumin and ribonucleases A and T1 are compared and contrasted. In each species, whatever conformation favours one disulphide bond over another is stabilized to the same extent by the presence of that disulphide bond in the disulphide intermediates. The pathways differ markedly in the nature of that conformation: in bovine pancreatic trypsin inhibitor a crucial intermediate is partly folded, in alpha-lactalbumin the intermediates tend to adopt to varying extents the molten globule conformation, while in the ribonucleases the early disulphide intermediates are largely unfolded, and none predominate. In each case, however, the slowest step is formation of a disulphide bond that will be buried in a stable folded conformation; the most rapid step is formation of an accessible disulphide bond on the surface of a folded conformation. Quasi-native species with the native conformation, but incomplete disulphide bonds, can either increase or decrease the rate of further disulphide formation.