A standardised study to compare prostate cancer targeting efficacy of five radiolabelled bombesin analogues

Purpose: Prostate-specific antigen (PSA)-based screening for prostate cancer (PC) has dramatically increased early diagnosis. Current imaging techniques are not optimal to stage early PC adequately. A promising alternative to PC imaging is peptide-based scintigraphy using radiolabelled bombesin (BN) analogues that bind to gastrin-releasing peptide receptors (GRPR) being overexpressed in PC. When labelled to appropriate radionuclides BN targeting of GRPRs may also provide applications for peptide radionuclide receptor therapy (PRRT). Assessment studies under identical experimental conditions allowing a reliable comparison of the potential of such analogues are lacking. This study was performed to evaluate and directly compare five promising radiolabelled BN analogues for their targeting efficacy for PC under standardised conditions. Methods: The BN agonists [111In]DOTA-PESIN, [111In]AMBA, [111In]MP2346 and [111In]MP2653 and one antagonist [99mTc]Demobesin-1 were evaluated in GRPR-overexpressing human PC-3 tumou

Use of Step-Section Histopathology to Evaluate 18

To assess positron emission tomography (PET) with fluorine-18 fluorocholine for sextant localization of malignant prostate tumors. Histopathologic analysis was performed on step-sectioned whole-mounted prostate specimens from 15 patients who underwent PET with fluorocholine prior to radical prostatectomy. The maximum standardized uptake value (SUVmax) corresponding to prostate sextants on PET was measured by region of interest analysis and compared with histopathologic results. Histopathology demonstrated malignant involvement in 61 of 90 prostate sextants. The mean total tumor volume per specimen was 4.9 mL (range 0.01–28.7 mL). Mean SUVmax was 6.0 ± 2.0 in malignant sextants and 3.8 ± 1.4 in benign sextants ( p < .0001). The area under the receiver operating characteristic curve was 0.82 for sextant detection of malignancy based on SUVmax measurement. Tumor diameter directly correlated with sextant SUVmax in malignant sextants ( r = .54, p < .05). In 13 subjects, the largest tumor in the specimen corresponded to the sextant with the highest SUVmax. Fluorocholine PET can serve to localize dominant areas of malignancy in patients with prostate cancer. However, PET with fluorocholine may fail to identify sextants with smaller volumes of malignancy