68Ga-PSMA-11 PET Has Specificity of 0.95 for Pelvic Nodal Metastases

68Ga-prostate-specific membrane antigen (PSMA)-11-positron emission tomography (PET) imaging has sensitivity of 0.40 and specificity of 0.95 for detection of pelvic nodal metastases in men with intermediate- to high-risk prostate cancer who undergo radical prostatectomy and lymph node dissection, according to a study published online in JAMA Oncology.

Thomas A. Hope, MD, from the University of California in San Francisco, and colleagues examined the accuracy of 68Ga-PSMA-11 PET imaging for the detection of pelvic nodal metastases in a prospective multicenter single-arm open-label phase 3 imaging trial. A total of 764 patients with intermediate- to high-risk prostate cancer considered for prostatectomy were enrolled; 277 (36 percent) subsequently underwent prostatectomy with lymph node dissection (efficacy analysis cohort).

The researchers found that 75 of the patients (27 percent) had pelvic lymph node metastasis based on pathology reports. Results of 68Ga-PSMA-11 PET were positive for pelvic nodal, extrapelvic nodal, and bone metastatic disease in 40, two, and seven of 277 patients (14, 1, and 3 percent, respectively). For pelvic nodal metastases, the sensitivity, specificity, positive predictive value, and negative predictive value were 0.40, 0.95, 0.75, and 0.81, respectively. Overall, 487 of the 764 patients did not undergo prostatectomy; 108 of these patients were lost to follow-up. Patients with follow-up underwent radiotherapy, systemic therapy, surveillance, and other treatments (69, 22, 4, and 5 percent, respectively).

“The results of this study were used to support the U.S. Food and Drug Administration approval of 68Ga-PSMA-11 PET at initial staging,” the authors write.

Several authors disclosed financial ties to the biopharmaceutical industry.

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