ASCO 2017: Effect of Ga-68 PSMA-11 PET on management in patients with recurrent prostate cancer

Chicago, IL ( Up to 30% of prostate cancer (PC) patients after definitive local therapy have biochemical recurrence (BCR). PET imaging of prostate specific membrane antigen (PSMA) has been shown to have a higher sensitivity and specificity compared to conventional imaging. Dr. Tom Hope presented a study attempting to evaluate the impact of PSMA PET on the management of PC patients with BCR following local therapy (Clinical trial information: NCT02611882).

Overall, 150 patients from December 2015 to October 2016 were enrolled in this prospective trial evaluating the use of PSMA PET in the staging of PC patients. Inclusion criteria required a PSA doubling time less than 12 months. 63 patients were imaged using PET/CT (GE Discovery VCT) and 63 patients using PET/MRI (GE Signa 3.0T PET/MRI). Referring clinicians filled out a pretreatment management form and a management form based on the imaging results. Changes in management were graded as major, minor, no change, or unknown based upon the responses. 

A total of 126 forms were received with an 84% response rate. The average PSA in the population was 5.9 ± 5.4 ng/mL with an average doubling time of 9.7 ± 11.0 months, and 49 patients had a PSA of less than 2.0 at the time of imaging. The average time between prior treatment and imaging (RP and/or radiation) was 5.3 ± 5.4 years, with 46 patients imaged within two years of their most recent treatment. 43 patients had a prior prostatectomy, 41 prior to radiation, and 33 patients had both. 103 patients (82%) had disease localized on PSMA imaging. Of the 126 patients, 67 (53%) of the imaging studies resulted in a major change in management. The most common major change was converting from active surveillance to radiation therapy (15 patients, 12%), changing from androgen deprivation therapy (ADT) to radiation therapy (16 patients, 13%), and converting from radiation therapy to either active surveillance (6 patients, 5%) or to ADT alone (3 patients, 2%). 10 patients (8%) had a minor change, 42 patients (33%) had no change, and 7 patients (6%) had an unknown change in management. 

The results of our surveys demonstrate a substantial impact of PSMA PET on the intended patient management. The majority of changes involved converting a targeted therapy to systemic treatment, or systemic treatment to a targeted therapy. Prospective studies are warranted to determine whether directed treatment towards PSMA-avid lesions affects long-term disease outcomes. 

Presented by: Tom Hope, MD, University of California San Francisco Helen Diller Family Comprehensive Cancer Center, San Francisco, CA

Written By: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre, Toronto, Ontario, Canada
Twitter: @GoldbergHanan

at the 2017 ASCO Annual Meeting - June 2 - 6, 2017 - Chicago, Illinois, USA