Prostate specific membrane antigen (PSMA) PET/MRI can determine whether cancer is likely to return within two years after prostatectomy in men recently diagnosed with intermediate or high-grade prostate cancer. Because prostate cancer has widely varying outcomes after treatment, this information could be pivotal in guiding patient management.
“PSMA PET/MRI adds value to the pre-therapy evaluation of patients with newly diagnosed prostate cancer, and the information from PET seems to be as reliable, if not more reliable, than biopsy findings and clinical information in predicting which patients will have suboptimal outcome,” said lead author Farshad Moradi, MD, PhD, clinical associate professor of Radiology–Nuclear Medicine at Stanford University Medical Center.
There are several imaging modalities that can be used in prostate cancer patients, but Moradi told Inside Precision Medicine that they chose PET/MRI “Because they provide complementary information.” The downside is the cost and availability of the techniques and the added radiation from PET. “We are hoping that our study and others will identify which patients will benefit most from PSMA PET.”
This research was published in the December issue of The Journal of Nuclear Medicine and led by Andrei Iagaru, MD, professor of Radiology–Nuclear Medicine and chief of the Division of Nuclear Medicine and Molecular Imaging at Stanford University Medical Center.
About 1 in 8 men will be diagnosed with prostate cancer during their lifetime, according to the American Cancer Society. ACS reports that it is the second leading cause of cancer death in American men, behind only lung cancer, with 1 man in 41 dying from this type of malignancy.
But many cases of localized prostate cancer are treated successfully. It is vital to predict which patients will instead experience a rapid progression even after prostatectomy or radiation therapy.
“Clinicians currently use biopsy findings and clinical information, such as prostate-specific antigen (PSA) levels, to predict if prostate cancer is slow-growing or if it will spread quickly and require aggressive treatments,” said Iagaru. “However, functional imaging, such as PET/MRI, is increasingly being considered as a way to identify patients at risk for persistent or recurrent disease.”
These researchers examined the value of 68Ga-PSMA-11 PET/MRI for risk stratification of newly diagnosed prostate patients prior to initial therapy. Seventy-three patients with a new diagnosis of intermediate- or high-grade prostate cancer were imaged with 68Ga-PSMA-11 PET/MR between April 2016 and December 2020.
PET findings were divided into groups based on low versus high uptake in the primary lesion and the presence or absence of metastatic disease. These findings were compared to biopsy results and clinical information. The relationship between the PET/MRI findings and patient outcomes were also examined.
High uptake in the primary lesion and the presence of PSMA avid metastasis were associated with rapid recurrence within two years of prostatectomy. In contrast, patients with low uptake in the primary lesion who did not have evidence of metastatic disease on PET/MRI had a low likelihood of experiencing recurrence during the follow-up period.
Moradi said, “This study provides support for including PSMA PET to aid in clinical decision making about prostate cancer therapy options. PSMA pre-surgery may contribute to establishing one of the ‘killer applications’ for PET/MRI.”
PET/MRI is also being used in primary diagnosis of prostate cancer. A recent review found that PET/MRI was “highly sensitive” in detecting primary prostate cancer, particularly when used with radio labeled PSMA. Researchers at the University of Gothenburg in Sweden Found they could halve the risk of over-diagnosis of this disease using PSA blood tests followed by MRI.
The Stanford team will pursue further studies, such as, “Utility of PSMA PET/MRI in patients that plan to undergo novel localized treatments, including high intensity focused ultrasound ablation,” Moradi told IPM.
