clinical topic updates

Imaging Techniques in Metastatic Prostate Cancer

by Peter R. Carroll, MD, MPH

Overview

Although their impact on oncologic outcomes should be better defined, next-generation imaging techniques such as gallium-68 (68Ga) prostate-specific membrane antigen (PSMA) positron emission tomography (PET) and 18F fluciclovine PET have been increasingly adopted into clinical practice. These tools can change treatment planning, and many clinicians expect that outcomes will improve accordingly.

Expert Commentary

Peter R. Carroll, MD, MPH

Ken and Donna Derr – Chevron Distinguished Professor
Taube Family Distinguished Professor in Urology
Department of Urology
UCSF - Helen Diller Comprehensive Cancer Center
University of California, San Francisco
San Francisco, CA

“PSMA-based imaging will become the dominant form of next-generation imaging in this country, as it is around the world.”

Peter R. Carroll, MD, MPH

The US Food and Drug Administration (FDA) recently approved PSMA PET imaging at the University of California, San Francisco (UCSF) and the University of California, Los Angeles, and based on that application, others will follow suit. Fluciclovine was previously approved for use in men who have a rising prostate-specific antigen following prior definitive therapy. The approval for 68Ga PSMA PET imaging included its use both at the time of diagnosis and at the time of recurrence. 68Ga PSMA has an FDA-approved indication for both uses. Even more recently, the FDA approved 18F-DCFPyL PSMA PET based on data from the OSPREY (NCT02981368) and CONDOR (NCT03739684) trials. In terms of imaging in metastatic prostate cancer, my sense is that PSMA-based imaging will become the dominant form of next-generation imaging in this country, as it is around the world. 

We know that PSMA at either the time of diagnosis or the time of recurrence gives you unique information in a very large percentage of patients. That information results in changes to the treatment plan compared with planning based on conventional imaging. Whether those treatment changes will result in improved long-term outcomes is not yet known. We do believe that outcomes will be improved, and we are involved in clinical trials designed to study that question. 

Our experience at UCSF suggests that, in the setting of definitive treatment failure, the treatment plan will change with PSMA-based imaging (compared with conventional imaging) in approximately 30% to 40% of cases. A driving factor for these changes is the detection of additional involved lymph nodes using PSMA—lymph nodes outside of the areas originally included in the treatment plan. Once such sites have been identified, if you are planning to administer radiation, you can include nodes that are not in the original field and boost the dose to sites of disease. Instead of giving 45 Gray, you can actually administer stereotactic radiation therapy to these sites. A study is underway (NCT03582774) that is comparing standard-of-care salvage radiotherapy to salvage radiation therapy planned with the benefit of PSMA PET imaging.

When PSMA imaging is performed either at the time of diagnosis or at the time of biochemical relapse, you most commonly identify regional or retroperitoneal disease, rather than metastatic disease. At UCSF, we found that only around 24% of the patients who had failed previous treatment and had a rising prostate-specific antigen had bone or visceral metastases, but a rather substantial number had regional or retroperitoneal disease. Thus, another facet of next-generation imaging is its role in identifying oligometastatic disease. Patients with oligometastatic disease have metastases in relatively few sites (eg, 2-6 sites), and there has been a trend toward aggressive treatment in these patients. Instead of using systemic therapy alone, one might employ systemic therapy plus stereotactic body radiation and, in some cases, surgery. Again, we never knew that this whole new category of disease existed because we did not have the imaging tools that allowed us to detect it.

References

ClinicalTrials.gov. Multicenter randomized trial of 68Ga-PSMA-11 PET/CT based SRT after radical prostatectomy (PSMA SRT). Accessed June 23, 2021. https://clinicaltrials.gov/ct2/show/NCT03582774

ClinicalTrials.gov. Study of 18F-DCFPyL PET/CT imaging in patients with prostate cancer (OSPREY). Accessed June 23, 2021. https://clinicaltrials.gov/ct2/show/NCT02981368

ClinicalTrials.gov. Study of 18F-DCFPyL PET/CT imaging in patients with suspected recurrence of prostate cancer (CONDOR). Accessed June 23, 2021. https://clinicaltrials.gov/ct2/show/NCT03739684

Ghafoor S, Burger IA, Vargas AH. Multimodality imaging of prostate cancer. J Nucl Med. 2019;60(10):1350-1358. doi:10.2967/jnumed.119.228320

Muehlematter UJ, Burger IA, Becker AS, et al. Diagnostic accuracy of multiparametric MRI versus 68Ga-PSMA-11 PET/MRI for extracapsular extension and seminal vesicle invasion in patients with prostate cancer. Radiology. 2019;293(2):350-358. doi:10.1148/radiol.2019190687

Patel DN, Karsh LI, Daskivich TJ. Next-generation imaging in localized high-risk prostate cancer. Prostate Cancer Prostatic Dis. 2021 Mar 31. doi:10.1038/s41391-021-00356-x

Perera M, Papa N, Roberts M, et al. Gallium-68 prostate-specific membrane antigen positron emission tomography in advanced prostate cancer-updated diagnostic utility, sensitivity, specificity, and distribution of prostate-specific membrane antigen-avid lesions: a systematic review and meta-analysis. Eur Urol. 2020;77(4):403-417. doi:10.1016/j.eururo.2019.01.049

Tanaka T, Yang M, Froemming AT, et al. Current imaging techniques for and imaging spectrum of prostate cancer recurrence and metastasis: a pictorial review. Radiographics. 2020;40(3):709-726. doi:10.1148/rg.2020190121

Trabulsi EJ, Rumble RB, Jadvar H, et al. Optimum imaging strategies for advanced prostate cancer: ASCO guideline. J Clin Oncol. 2020;38(17):1963-1996. doi:10.1200/JCO.19.02757

Turpin A, Girard E, Baillet C, et al. Imaging for metastasis in prostate cancer: a review of the literature. Front Oncol. 2020;10:55. doi:10.3389/fonc.2020.00055

More in Prostate Cancer

Thumb

Prostate Cancer

Identifying the High-Risk Patient: Prognostic Markers in Advanced Prostate Cancer

Expert Roundtables by Glen Gejerman, MD, Daniel J. George, MD, William K. Oh, MD, and Neal D. Shore, MD, FACS

Although the incidence of metastatic prostate cancer decreased with the introduction of PSA-based screening, prostate cancer will still be responsi...READ MORE

Thumb

Prostate Cancer

Newer PET/CT Imaging Techniques Promise to Improve Detection of Metastatic Prostate Cancer

Patient Care Perspectives by Peter R. Carroll, MD, MPH, Neal D. Shore, MD, FACS

The question of defining metastatic disease with available imaging techniques is an important one. Globally, current standard imaging techniques in...READ MORE

Thumb

Prostate Cancer

Newer Options for Osseous Metastases in Advanced Prostate Cancer

Clinical Topic Updates by Daniel J. George, MD, Neal D. Shore, MD, FACS

As with other epithelial cancers, metastasis to the bone is a sentinel event in the development of advanced prostate cancer. The bone microenvironm...READ MORE

More In Oncology

GIST

Gastrointestinal Stromal Tumors: Managing Side Effects of Targeted Therapies

Expert Roundtables
by Michael C. Heinrich, MD; Arun Singh, MD; and Jonathan C. Trent, MD, PhD

GIST

Optimization of Therapeutic Strategies for Patients With Gastrointestinal Stromal Tumors

Expert Roundtables
by Michael C. Heinrich, MD; Arun Singh, MD; and Jonathan C. Trent, MD, PhD

GIST

The Impact of Gastrointestinal Stromal Tumors on Quality of Life

Patient Care Perspectives
by Jonathan C. Trent, MD, PhD