Impact of 11C-choline PET/CT on clinical decision making in recurrent prostate cancer: results from a retrospective two-centre trial.

PURPOSE: The aim of this retrospective two-centre study was to investigate the clinical impact of (11)C-choline PET/CT on treatment management decisions in patients with recurrent prostate cancer (rPCa) after radical therapy. METHODS: Enrolled in this retrospective study were 150 patients (95 from Bologna, 55 from Würzburg) with rPCa and biochemical relapse (PSA mean ± SD 4.3 ± 5.5 ng/mL, range 0.2-39.4 ng/mL) after radical therapy. The intended treatment before PET/CT was salvage radiotherapy of the prostatic bed in 95 patients and palliative androgen deprivation therapy (ADT) in 55 patients. The effective clinical impact of (11)C-choline PET/CT was rated as major (change in therapeutic approach), minor (same treatment, but modified therapeutic strategy) or none. Multivariate binary logistic regression analysis included PSA level, PSA kinetics, ongoing ADT, Gleason score, TNM, age and time to relapse. RESULTS: Changes in therapy after (11)C-choline PET/CT were implemented in 70 of the 150 patients (46.7%). A major clinical impact was observed in 27 patients (18%) and a minor clinical impact in 43 (28.7%). (11)C-choline PET/CT was positive in 109 patients (72.7%) detecting local relapse (prostate bed and/or iliac lymph nodes and/or pararectal lymph nodes) in 64 patients (42.7%). Distant relapse (paraaortic and/or retroperitoneal lymph nodes and/or bone lesions) was seen in 31 patients (20.7%), and both local and distant relapse in 14 (9.3%). A significant difference was observed in PSA level and PSA kinetics between PET-positive and PET-negative patients (p < 0.05). In multivariate analysis, PSA level, PSA doubling time and ongoing ADT were significant predictors of a positive scan (p < 0.05). In statistical analysis no significant differences were observed between the Bologna and Würzburg patients (p > 0.05). In both centres the same criteria to validate PET-positive findings were used: in 17.3% of patients by histology and in 82.7% of patients by correlative imaging and/or clinical follow-up (follow-up mean 20.5 months, median 18.3 months, range 6.2-60 months). CONCLUSION: (11)C-Choline PET/CT had a significant impact on therapeutic management in rPCa patients. It led to an overall change in 46.7% of patients, with a major clinical change implemented in 18% of patients. Further prospective studies are needed to evaluate the effect of such treatment changes on patient survival.

Somatostatin receptor expression in small cell lung cancer as a prognostic marker and a target for peptide receptor radionuclide therapy.

Despite initial responsiveness to both chemotherapy and radiotherapy, small cell lung cancer (SCLC) commonly relapses within months. Although neuroendocrine characteristics may be difficult to demonstrate in individual cases, a relevant expression of somatostatin receptors (SSTR) on the cell surface has been described. We aimed to evaluate the prognostic value of SSTR-expression in advanced SCLC. We further examined pre-requisites for successful peptide receptor radionuclide therapy (PRRT). 21 patients with extensive stage SCLC were enrolled. All patients underwent positron emission tomography/computed tomography (PET/CT) with 68Ga-DOTATATE to select patients for SSTR-directed therapy. PET scans were visually and semi-quantitatively assessed and compared to SSTR2a and SSTR5 expression in biopsy samples. Peak standardized uptake values (SUVpeak) of tumors as well as tumor-to-liver ratios were correlated to progression-free (PFS) and overall survival (OS). In 4/21 patients all SCLC lesions were PET-positive. 6/21 subjects were rated "intermediate" with the majority of lesions positive, the remaining 11/21 patients were PET-negative. PET-positivity correlated well with histologic SSTR2a, but not with SSTR5 expression. Neither PET-positivity nor SUVpeak were predictors of PFS or OS. In 4 patients with intensive SSTR2a-receptor expression, PRRT was performed with one partial response and one stable disease, respectively. SSTR-expression as detected by 68Ga-DOTATATE-PET and/or histology is not predictive of PFS or OS in patients with advanced SCLC. However, in patients exhibiting sufficient tracer uptake, PRRT might be a treatment option given its low toxicity and the absence of effective alternatives.