Hubert R. Kuebler

The sensitivity of [11C]choline PET/CT to localize prostate cancer depends on the tumor configuration.

Purpose: To evaluate the dependency of the sensitivity of [11C]choline positron emission tomography/computed tomography (PET/CT) for detecting and localizing primary prostate cancer (PCa) on tumor configuration in the histologic specimen. Experimental Design: Forty-three patients with biopsy-proven PCa were included. They underwent radical prostatectomy within 31 days after [11C]choline PET/CT. The transaxial image slices and the histologic specimens were analyzed by comparing the respective slices. Maximum standardized uptake values (SUVmax) were calculated in each segment and correlated with histopathology. The tumor configuration in the histologic specimen was grouped as: I, unifocal; II, multifocal; III, rind-like shaped; IV, size <5 mm. Data analysis included the investigation of detection of PCa by SUVmax, the assessment of the influence of potential contributing factors on tumor prediction, and the evaluation of whether SUV could discriminate cancer tissue from benign prostate hyperplasia (BPH), prostatitis, HGPIN (high-grade prostate intraepithelial neoplasm), or normal prostate tissue. General estimation equation models were used for statistical analysis. Results: Tumor configuration in histology was classified as I in 21 patients, as II in 9, as III in 5, and as IV in 8. The prostate segment involved by cancer is identified in 79% of the patients. SUVmax was located in the same side of the prostate in 95% of patients. Tumor configuration was the only factor significantly negatively influencing tumor prediction (P < 0.001). PCa-SUVmax (median SUVmax = 4.9) was not significantly different from BPH-SUV (median SUVmax = 4.5) and prostatitis-SUV (median SUVmax = 3.9), P = 0.102 and P = 0.054, respectively. Conclusions: The detection and localization of PCa in the prostate with [11C]choline PET/CT is impaired by tumor configuration. Additionally, in our patient population, PCa tissue could not be distinguished from benign pathologies in the prostate. Clin Cancer Res; 17(11); 3751–9. ©2011 AACR.

Prediction of favorable outcome in a docetaxel rechallenge setting in metastatic castration-resistant prostate cancer.

68 Background: To identify predictors of favourable oncological outcome in metastatic castration-resistant prostate cancer (mCRPC) patients who are treated with docetaxel rechallenge following first-line chemotherapy with docetaxel. METHODS We retrospectively evaluated the oncological outcome of mCRPC patients who were treated with 3-weekly docetaxel (75mg/m2) at first-line chemotherapy and rechallenge plus prednisone/ prednisolone. The endpoints of oncological outcome were PSA-progression-free survival (PSA-PFS) and overall survival (OS) after initiation of docetaxel rechallenge. The effect of clinical variables on PSA-PFS and OS was statistically analysed by a log-rank test or Cox regression with hazard ratios. All analyses were performed using a 0.05 level of significance. RESULTS 47 patients were included on analysis. At a median follow-up of 25.8 months (range 9.8-89.8 months) after the first administration of docetaxel, 27 (57.4%) patients had died. Median PSA-PFS was 5.9 months (95% CI 3.5-6.8 months) and median OS was 21.4 months (95% CI 18.9-23.9 months) after initiation of docetaxel rechallenge. PSA-reduction ≥ 30% was the only pre-treatment variable that correlated significantly with prolonged PSA-PFS (p=0.03) and OS (p=0.002). Patients with PSA-reduction ≥ 30% at first-line chemotherapy showed a median OS of 21.8 months since initiation of docetaxel rechallenge in comparison to 4.5 months in patients with < 30% PSA-reduction. CONCLUSIONS Docetaxel rechallenge represents an active treatment option in selected docetaxel-pretreated patients with mCRPC. In this retrospective study, PSA-reduction ≥ 30% at first-line chemotherapy with docetaxel predicted superior PSA-PFS and OS in the rechallenge setting and might, therefore, present a rational indication for docetaxel rechallenge.