Christopher Cheng

Ultrasound Guided Robotic System for Transperineal Biopsy of the Prostate

We present a prototype of a robotic system for accurate and consistent insertion of a percutaneous biopsy needle into the prostate. The robot manipulates a transrectal ultrasound (TRUS) probe to collect a series of 2 dimensional (2D) images of the prostate, which are later used to create a 3D computer model of the organ. The urologist defines the needle’s entry point at the perineal wall and the biopsy points within the 3D model following a biopsy protocol or otherwise. The robotic system then calculates the required trajectory of the needle. The path of the needle going into the prostate can also be simulated with the 3D model before the actual insertion. Being satisfied with the predicted outcome, the urologist configures the robot accordingly and manually pushes the mechanically guided needle into the patient to take the biopsy. Cadaveric and human trials have validated the robot’s needle placement error to be less than 2.5mm. Our future work includes the integration of a cancer predictive modality into the system to increase the cancer detection rate. The robotic system could also be modified to accurately place foreign bodies into the prostate, which could improve therapeutic procedures such as Brachytherapy.

Clinical, biochemical and pathological features of initial and repeat transrectal ultrasonography prostate biopsy positive patients

Background: Using sextant biopsy, 16–41% of prostate cancers were diagnosed on repeat biopsy. The objective of the present study was to compare the differences in the clinical, biochemical and pathological features between patients with positive results on initial and repeat biopsies, with an aim to identify factors that can be used to improve the detection rate of transrectal ultrasound (TRUS) biopsy of the prostate.

ULTRASOUND GUIDED ROBOTIC BIOPSY OF THE PROSTATE

In this paper, a prototype of a robotic system for accurate and consistent insertion of a percutaneous biopsy needle into the prostate is presented. A transrectal ultrasound (TRUS) probe is used to collect a series of two-dimensional (2D) images of the prostate. These images are used to create a 3D computer model of the organ which is used by the urologist to define the biopsy points within the prostate. The robotic system then calculates the required trajectory of the needle, which can be simulated on the computer. Following this, the robot is configured accordingly and the actual biopsy is performed. Cadaveric and human trials have validated the robots needle placement error to be less than 2.5 mm. Our future work includes the integration of a cancer predictive modality into the system to increase the cancer detection rate. The robotic system could also be modified to accurately place foreign bodies into the prostate, which could improve therapeutic procedures such as Brachytherapy.

Sun Exposure and the Risk of Prostate Cancer in the Singapore Prostate Cancer Study: a Case-control Study

BACKGROUND Most of the epidemiology studies on the effects of sun exposure and prostate cancer were conducted among the temperate countries of North America and Europe. Little is known about the influence on Asian populations. The purpose of current study was to evaluate any association of sun exposure with risk of prostate cancer in Chinese, Malays and Indians who reside in the tropics. METHODS The Singapore Prostate Cancer Study is a hospital-based case-control study of 240 prostate cancer incident cases and 268 controls conducted in Singapore between April 2007 and May 2009. Detailed information on outdoor activities in the sun, skin colour, sun sensitivity and other possible risk factors were collected in personal interviews. Cases were further classified by Gleason scores and TNM staging. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression analysis, adjusted for age, ethnicity, education, family history of any cancers, BMI and skin colour. RESULTS We found that prostate cancer risk was increased in subjects with black/dark-brown eyes (OR 5.88, 95%CI 3.17-10.9), darker skin colour e.g. tan/dark brown/black (OR 7.62, 95%CI 3.41-17.0), frequent sunburn in lifetime (OR 4.30, 95%CI 1.7-11.2) and increased general sun exposure in adulthood per week (OR 2.03, 95%CI 1.09-3.81). The increased risk was consistent for high grade tumours and advanced stage prostate cancers. CONCLUSION The findings from this study suggest that excessive sun exposure is a risk factor for prostate cancer in Asians.

Renal cell carcinoma in patients with end-stage renal disease is associated with more favourable histological features and prognosis

Abstract Objective. End-stage renal disease (ESRD) patients with acquired cystic kidney disease are at higher risk of developing renal cell carcinoma (RCC) than the general population. The aim of this study was to investigate the clinical and histopathological differences between ESRD patients and the general population with RCC. Materials and methods. Data were retrospectively collected from all nephrectomies performed for localized RCC from 2000 to 2010. Age at nephrectomy, gender, race, symptoms, baseline Eastern Cooperative Oncology Group (ECOG) performance status, Charlson Comorbidity Index score and histological data were extracted. Independent-samples t test and Mann–Whitney test were used for quantitative data, while chi-squared (two-sided) and Fisher’s exact tests were used for qualitative data. Results. This study included 627 patients: 73 with and 554 without ESRD. The majority of patients were Chinese. The male to female ratio of 2:1 was identical in both groups. Baseline ECOG performance status and Charlson Comorbidity score were higher in the ESRD group. RCC in ESRD patients was more frequently asymptomatic (56.2% vs 44.9%, p = 0.071), diagnosed earlier (53.6 ± 11.8 years vs 57.9 ± 12.2 years, p = 0.004) and of lower stage (p < 0.001). The ESRD cohort had a higher proportion of the papillary histological subtype (21.9% vs 9.7%, p < 0.001). Importantly, there was a trend towards more favourable outcomes in ESRD patients in terms of cancer-specific (p = 0.203) and relapse-free survival (p = 0.096). Conclusion. This study suggests that RCC in ESRD patients is associated with more favourable clinical and histological features and oncological outcome compared with that in patients with normal renal function.

Focal Therapy for Prostate Cancer with In-Bore MR–guided Focused Ultrasound: Two-Year Follow-up of a Phase I Trial—Complications and Functional Outcomes

Purpose To report the safety profile and 2-year functional outcomes of in-bore magnetic resonance (MR)-guided focused ultrasound on single cancer foci in men with prostate cancer. Materials and Methods Ethics approval was obtained from the centralized institutional review board for this prospective single-arm study, and patients provided informed consent. Patients with untreated low-volume low-grade prostate cancer (clinical stage T2a or lower; Gleason score, 3+3; index tumor ≤10 mm3) underwent MR-guided focused ultrasound between July 2011 and February 2013. All patients underwent robotic transperineal mapping biopsy and multiparametric MR imaging. Only those with a maximum of two lesions smaller than 10 mm at mapping biopsy were included. Target areas were sonicated with real-time MR thermometry monitoring, excluding critical areas from the beam path. Serum prostate-specific antigen (PSA) and Expanded Prostate Index Composite (EPIC) scores were obtained at baseline and at 1, 3, 6, 12, 18, and 24 months and were plotted to observe their trend. Mean EPIC subdomain score changes at each serial time point were compared with the baseline score by using paired t tests (level of significance, P < .007). Repeat transperineal biopsy was performed at 6 and 24 months. Results Fourteen men (mean age, 62.8 years; median PSA level, 8.3 ng/mL) underwent treatment, with 12 men completing 2-year follow-up. A median reduction of PSA level by 2.9 ng/mL was observed at 6 months. Seven men had Clavien-Dindo grade 1-2 complications. There was a slight insignificant deterioration of EPIC urinary symptom score (mean increase of 7.8 points compared with baseline, P = .012) noted at 1 month, but it returned to baseline by 3 months. There was a trend to deterioration in sexual function score (mean decrease, 4.4 points; P = .04 [not significant]) that normalized at 3 months. There was no significant change in EPIC subdomain scores from baseline over the 24 months. At 6-month template biopsy, one man had cancer with a Gleason score greater than 6; at 24 months, three men had cancer with a Gleason score greater than 6. Conclusion MR-guided focused ultrasound is technically feasible for focal prostate ablation and appears to have a favorable early safety and functional profile. Further clinical trials are necessary to establish oncologic efficacy.