Prospective comparative study of18F-sodium fluoride PET/CT and planar bone scintigraphy for treatment response assessment of bone metastases in patients with prostate cancer.

To compare18F-sodium fluoride positron emission tomography/computed tomography (NaF PET/CT) and99mTc-labelled diphosphonate bone scan (BS) for the monitoring of bone metastases in patients with prostate cancer undergoing anti-cancer treatment.

Data from 64 patients with prostate cancer were included. The patients received androgen-deprivation therapy (ADT), next-generation hormonal therapy (NGH) or chemotherapy. The patients had a baseline scan and 1-3 subsequent scans during six months of treatment. Images were evaluated by experienced nuclear medicine physicians and classified for progressive disease (PD) or non-PD according to the Prostate Cancer Working Group 2 (PCWG-2) criteria. The patients were also classified as having PD/non-PD according to the clinical and prostate-specific antigen (PSA) responses.

There was no difference between NaF PET/CT and BS in the detection of PD and non-PD during treatment (McNemar's test, p = .18). The agreement between BS and NaF PET/CT for PD/non-PD was moderate (Cohen's kappa 0.53, 95% confidence interval 0.26-0.79). Crude agreement between BS and NaF PET/CT for the assessment of PD/non-PD was 86% (89% for ADT, n = 28; 88% for NGH, n = 16, and 80% for chemotherapy, n = 20). In most discordant cases, BS found PD when NaF PET/CT did not, or BS detected PD on an earlier scan than NaF PET/CT. Biochemical progression (27%) occurred more frequently than progression on functional imaging (BS, 22% and NaF PET/CT, 14%). Clinical progression was rare (11%), and almost exclusively seen in patients receiving chemotherapy.

There was no difference between NaF PET/CT and BS in the detection of PD and non-PD; however, BS seemingly detects PD by the PCWG-2 criteria earlier than NaF-PET, which might be explained by the fact that NaF-PET is more sensitive at the baseline scan.

Acta oncologica (Stockholm, Sweden). 2018 Feb 15 [Epub ahead of print]

Randi Fuglsang Fonager, Helle Damgaard Zacho, Niels Christian Langkilde, Joan Fledelius, June Anita Ejlersen, Helle Westergreen Hendel, Christian Haarmark, Mette Moe, Jesper Carl Mortensen, Mads Ryø Jochumsen, Lars Jelstrup Petersen

a Department of Nuclear Medicine , Clinical Cancer Research Center, Aalborg University Hospital , Aalborg , Denmark., c Department of Urology , Aalborg University Hospital , Aalborg , Denmark., d Department of Nuclear Medicine , Regional Hospital West Jutland , Herning , Denmark., e Department of Clinical Physiology and Nuclear Medicine , Herlev Hospital , Herlev , Denmark., f Department of Oncology , Aalborg University Hospital , Aalborg , Denmark., g Department of Urology , Regional Hospital West Jutland , Holstebro , Denmark.