The use of PSMA-targeted 18F-DCFPyL-PET/CT may provide specific staging information in patients with prostate cancer recurrence or metastases on conventional imaging, according to a study. The results were presented during the 2021 ASCO Annual Meeting.
In the study, a total of 117 men underwent 18F-DCFPyL-PET/CT. All patients had local recurrence or metastatic disease per CT, MR, or whole-body bone scintigraphy and had at least one lesion amenable to biopsy. They received one dose of 9 mCi (333 MBq) of 18F-DCFPyL intravenously, and one to two hours later, PET/CT acquisition. The researchers used TNM staging to assess prostatic (T), pelvic LN (N), extra-pelvic LN (M1a), bone (M1b) and other visceral organs/soft tissue (M1c).
Overall, 82 patients (70%) had baseline radiographic M1 disease, including M1a (n=14), m1b (n=50), and m1c (n=18); 33 patients (28%) had M0 stage disease, and two patients were unevaluable. When using 18F-DCFPyL-PET/CT, more than half of patients were upstaged from M0 to M1 (n=19/33; 58%). A total of 91% of patients who underwent an extra-pelvic biopsy had confirmed M1 disease by pathology (n=10/11); nine of these patients had M1b and one had M1a.
Among patients with M1 disease at baseline, 16% were upstaged when using 18F-DCFPyL-PET/CT (n=10/64), including from M1a to M1b or M1c (n=4) or M1b to M1c (n=6); conversely, 22% of patients were down-staged (n=18/82) to M0.
“18F-DCFPyL-PET/CT identified M1 disease in most patients examined who otherwise had locoregional disease. These data suggest that 18F-DCFPyL-PET/CT may be a useful tool in properly staging men with both metastatic and nonmetastatic relapsed disease, which could lead to superior treatment paradigms than currently exist using conventional imaging,” the researchers wrote in their conclusion.