Niagara Falls, Ontario—Researchers have determined that 18F-fluorodeoxyglucose (FDG) positron emission tomography (FDG-PET), a widely available and relatively inexpensive imaging modality, could be used to shape treatment plans for patients who have been diagnosed with high Gleason score prostate cancer.
Frédéric Pouliot, MD, PhD, Urologist Oncologist, and Assistant Professor, Department of Surgery, Université Laval, Quebéc, Canada, and his team found that increased FDG uptake by the prostate is strongly correlated with factors that are indicative of a poor prognosis, such as advanced clinical stage, a pathologic Gleason score of ≥8, and percentage of intraprostatic cancer.
In addition, patients without intraprostatic FDG uptake had a high probability of 5-year progression-free survival (PFS), based on the MSKCC (Memorial Sloan-Kettering Cancer Center)’s pretreatment and the CAPRA-S (University of California, San Francisco Cancer of the Prostate Risk Assessment score) postradical prostatectomy nomograms. Patients with FDG uptake had a significantly lower probability of 5-year PFS, particularly based on the CAPRA-S results.
“These results suggest that with a single imaging modality, you might predict how your patients might do with surgery preoperatively,” said Dr Pouliot in a poster presentation at the 2013 Canadian Urological Association annual meeting.
The team analyzed information from 54 patients who had a Gleason score of ≥8 at transrectal ultrasound biopsy between July 2011 and July 2012 and who underwent an FDG-PET bone scan; 41 patients also had radical prostatectomy and extended pelvic lymph node dissection and the other 13 received androgen-deprivation therapy and/or radiotherapy.
FDG uptake had a 27% sensitivity for detecting lymph node metastases, a 100% specificity, and positive predictive value. It also was significantly correlated with a range of clinicopathologic factors, including clinical stage and pathologic Gleason score.
In addition, FDG uptake was predictive of prostatectomy-determined Gleason score. Fully 81.8% of the patients with increased FDG uptake had a Gleason score of ≥8. None were downstaged to Gleason 6 or 7 at prostatectomy.
Dr Pouliot’s team also found a 91.5% probability of 5-year PFS when they entered information from patients with FDG uptake into the MSKCC pretreatment nomogram. Patients without increased FDG uptake in the prostate had a 72.0% probability of 5-year PFS. Even more impressive discrimination was shown with the CAPRA-S nomogram—a 70.2% probability of 5-year PFS in patients with no FDG uptake and only a 26.9% probability in patients with increased uptake.
