For staging, the updated European Association of Urology guidelines do not explicitly mention PSMA PET-CT, however, do say that “evidence if rapidly evolving, in that choline PET/CT, PSMA PET-CT, and MRI provides a more sensitive detection of lymph node and bone metastases than the classical work-up associating bone scan and abdominopelvic CT”. In a recent study from Australia, Yaxley et al. retrospectively reviewed 1,253 consecutive men referred for 68 Ga-PSMA PET/CT scan for staging at the initial diagnosis.1 Metastatic disease was identified in 12.1% of men, including 8.2% with a PSA level of <10 ng/mL and 43% with a PSA level of >20 ng/mL. Metastases were identified in 6.4% with ISUP grade 2-3 and 21% with ISUP grade 4-5. Furthermore, lymph node metastases were suspected in 107 men, with 47.7% outside the boundaries of an extended pelvic lymph node dissection. Skeletal metastases were identified in 4.7%. In men with intermediate-risk prostate cancer, metastases were identified in 5.2%, compared to 19.9% with high-risk disease. Based on these results, according to Dr. Fanti, there appears to be a role for PSMA PET-CT in initial staging.
For biochemical recurrence, a recent systematic review of 98 studies found that at recurrent PSA levels <0.5ng/ml, detection rates were up to 31.3% using 11C choline PET-CT and up to 65.0% using 68Ga PSMA-11 PET-CT.2 Furthermore, at recurrent PSA levels <0.2ng/ml, detection rates of 68Ga PSMA-11 PET-CT ranged from 11.3% to as high as 58.3%. The updated European Association of Urology guidelines does recommend using PSMA PET-CT imaging in patients with persistent PSA after radical prostatectomy. However, the strength rating of this recommendation is still “weak” due to lack of knowledge regarding the effect of using this imaging modality on outcomes.
More recently, PSMA PET-CT has also been used in therapy planning. In a study of 100 patients with biochemical failure after radical prostatectomy ± prior radiation therapy who underwent 68 Ga-PSMA PET/CT or PET/MRI, uptake indicative for tumor recurrence in 68 Ga-PSMA-PET was found in 76% of the patients with biochemically recurrent prostate cancer.3 Taken together, 43% of all patients experienced a change in TNM stage due to 68 Ga-PSMA-PET imaging. Due to the additional knowledge of 68 Ga-PSMA-PET imaging, initially planned radiation therapy planning was adapted in 59% of all cases. Thus, even at low PSA levels, 68 Ga-PSMA-PET imaging may have an important clinical impact on staging and radiation therapy management in patients with biochemically recurrent prostate cancer. As part of treatment planning, theranostics has also emerged in the past several years.
In a phase two, single-arm, single-center trial assessing the role of 177Lu-PSMA-617 in patients with mCRPC, 50% of patients had more than a 50% PSA response, and 27% of patients had more than an 80% PSA response.4 These results are quite encouraging, but there is still more room for improvement.
Dr. Fanti concluded noting that PSMA PET-CT is (i) non-invasive, simple, and reproducible, (ii) allows clinicians to study local disease, nodes, bone, and other visceral organs with one imaging modality, (iii) is more sensitive than other imaging methods, and (iv) has rapid diffusion and is easy to implement.
Presented by: Stefano Fanti, MD, Director of PET Center, Director of Nuclear Medicine Division, Orsola-Malpighi Hospital, Professor of Diagnostic Imaging, University of Bologna, Bologna, Italy
Written by: Zachary Klaassen, MD, MSc – Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia at the 2019 Advanced Prostate Cancer Consensus Conference (APCCC) #APCCC19, Aug 29 - 31, 2019 in Basel, Switzerland
Read the Opposing Argument: Pitfalls of PSMA PET-CT in Advanced Prostate Cancer Imaging
- Yaxley JW, Raveenthiran S, Nouhaud FX, et al. Risk of metastatic disease on 68 gallium-prostate-specific membrane antigen positron emission tomography/computed tomography scan for primary staging of 1,253 men at the diagnosis of prostate cancer. BJU Int 2019 Sep;124(3):401-407.
- De Visschere PJL, Standaert C, Futterer JJ, et al. A systematic review on the role of imaging in early recurrent prostate cancer. Eur Urol Oncol 2019 Feb;2(1):47-76.
- Habl G, Sauter K, Schiller K, et al. 68 Ga-PSMA-PET for radiation treatment planning in prostate cancer recurrences after surgery: Individualized medicine or a new standard of salvage treatment.
- Hofman MS, Violet J, Hicks RJ, et al. [177Lu]-PSMA-617 radionuclide treatment in patients with metastatic castration-resistant prostate cancer (LuPSMA trial): a single-centre, single arm, phase 2 study. Lancet Oncol 2018 Jun;19(6):825-833.
Further Related Content: Advantages of PSMA PET in APC Imaging Presentation