Assessing androgen receptor (AR) expression and glycolytic activity using PET–CT imaging could be useful for predicting the prognosis of patients with metastatic castration-resistant prostate cancer (CRPC), say researchers.

Josef Fox and co-workers enrolled 133 patients with progressive metastatic CRPC to undergo dual PET–CT imaging using 18F-fluorodeoxyglucose (18F-FDG) as an indicator of tumour glycolysis and 18F-fluorodihydrotestosterone (18F-FDHT) as an indicator of AR expression.

The researchers classified lesions as being positive or negative for 18F-FDG uptake (noted as Glyc1 and Glyc0, respectively) and positive or negative for 18F-FDHT uptake (noted as AR1 and AR0, respectively). They identified three lesion phenotypes: AR1Glyc1, AR1Glyc0, and AR0Glyc1. Using multivariate analysis, they demonstrated that each of these three lesion phenotypes showed an independent negative correlation with survival. Each additional AR0Glyc1 lesion was associated with an 11% increase in the risk of death, each additional AR1Glyc1 lesion was associated with a 5% increase in the risk of death, and each additional AR1Glyc0 lesion was associated with a 3% increase in the risk of death.

Survival was significantly worse in patients with at least 12 metabolizing lesions (the median number) than in patients with fewer than 12 lesions (HR 3.01; P < 0.001). Using biopsy findings from 50 patients, Fox et al. also showed that 18F-FDHT positivity (AR1) was a highly specific marker for histological findings of prostate cancer. They say that future studies could investigate whether particular lesion subtypes are correlated with treatment response.