Objective Metastatic castration-resistant prostate cancers are aggressive tumors with poor prognosis. Prostate-specific membrane antigen-targeted radionuclide therapy is a potential treatment for these patients. Here, we report our initial experience in Singapore. Methods Twenty men (median age 70) with progressive disease were prospectively recruited. Prostate-specific membrane antigen and fluorodeoxyglucose-PET/computed tomography were performed to confirm high prostate-specific membrane antigen-expression. Up to four cycles of 177lutetium-prostate-specific membrane antigen-I&T at 6–8 weekly intervals were administered. Patients were restaged 3 months following treatment. Primary endpoints were prostate-specific antigen decline ≥50% and treatment-related toxicity. Additional endpoints included radiological and clinical response as well as progression-free survival and overall survival from first cycle. Results Sixty-seven cycles were administered (median 4 cycles per patient, mean 6.5 GBq per cycle). Sixty five percent had ≥1 line of prior chemotherapy, 90% abiraterone, enzalutamide or both, and 30% radium-223 radionuclide therapy. All had bone metastases and 35% had visceral metastases. Prostate-specific antigen decline ≥50% was achieved in 50%. Grade 3–4 hematotoxicity was seen in up to 15%. Grade 3–4 non-hematotoxicity was not observed. Eleven patients had restaging scans 3 months post-treatment (5 = partial response, 6 = progressive disease). Fifty-seven percent (4/7) with bone pain had pain improvement. Median progression-free survival was 5.9 months and median overall survival 13.1 months. Patients with prostate-specific antigen decline ≥50% had longer progression-free survival and overall survival. Conclusion 177Lutetium-prostate-specific membrane antigen-I&T therapy is effective with tolerable side effects in our local setting. Prostate-specific antigen decline ≥50% is associated with longer progression-free survival and overall survival.

Clinically significant changes in hepatic haemodynamics accompany the development of portal hypertension, hepatocellular carcinoma, liver metastases and liver cirrhoses, and after major liver resection. Hepatic blood flow parameters, such as hepatic arterial flow (HAF), hepatic portal flow (HPF), total hepatic blood flow (THBF) and hepatic perfusion index (HPI), are useful adjuncts to the diagnosis of liver pathology, the evaluation of disease progress and prognostication. Here, we describe a non-invasive method that combines the measurement of these parameters in a single study in real time. Red blood cells from eight pigs were labelled with 99Tc(m) using an in-vitro method and re-injected into the pigs. Data acquisition over the heart, lungs, liver and kidneys was started immediately and a blood sample was obtained 15 min post-injection. Hepatic arterial flow was determined from the ratio of the maximum gradients between the integrated time-activity curve of the left ventricle and the first-pass time-activity curve of the liver before the peak of the kidneys time-activity curve. The hepatic perfusion index was determined by comparing the slope of the liver time-activity curve before and after the kidney peak. Hepatic portal flow was determined from the hepatic arterial flow and the hepatic perfusion index, and total hepatic blood flow was determined as the sum of arterial and portal flow. The results were compared against those obtained from a clearance method using 99Tc(m)-DISIDA. The average hepatic perfusion index was 0.38, and the average hepatic arterial flow and hepatic portal flow were 168.3 +/- 52.9 and 274.6 +/- 60.1 ml x min(-1) respectively. The average total hepatic blood flow was 442.8 +/- 53.5 ml x min(-1), while the total hepatic flow determined by 99Tc(m)-DISIDA clearance was 419.7 +/- 62.6 ml x min(-1). No significant difference in total hepatic blood flow was found between the two methods. The results of this study show that it is possible to obtain all hepatic haemodynamics data in a single study using a non-invasive method.

No abstract

The use of radioactive substances in medicine accounts for the largest radiation exposure to the population from non-natural sources worldwide. The use in healthcare confers many benefits, but inappropriate or unskilled use can result in health hazards and safety issues for both patients and healthcare workers. We present two cases of radiation safety issues related to patients presenting to our emergency department after receiving non-conventional brachytherapy in the form of radiation seeds being implanted in the abdominal wall. These were done for presumed treatment of metastatic cancer in another Asian country. We share our cases to all emergency department staff to heighten their alertness for potential exposure to radiation from patients with radionuclides. (Hong Kong j.emerg.med. 2016;23:279-284) 2