Seyed Ali Mirshahvalad - Research Center for Nuclear Medicine, Dr. Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
Saeed Farzaneh Far - Valiasr Hospital, Tehran University of Medical Sciences
Mehrshad Abbasi - Department of Nuclear Medicine, Vali-Asr Hospital Tehran University of Medical Sciences, Tehran ۱۴۱۹۷۳۱۳۵۱, Iran

Objective(s): This study aimed to evaluate the therapeutic outcomes of ۱۷۷Lutetium (۱۷۷Lu)-PSMA-۶۱۷ in metastatic castrate-resistant prostate cancer (mCRPC) patients, based on post-treatment imaging findings. Methods: All post-therapeutic scans were collected retrospectively from patients treated with ۱۰۰-۲۰۰ mCi ۱۷۷Lu-PSMA-۶۱۷ from March ۲۰۱۸ to December ۲۰۲۰ for mCRPC. Two independent readers interpreted the scans and visually categorized them into three strata: responsive, stable, and progressive. The responses were defined based on changes in the number of detected lesions, as well as the intensity of the hottest lesion. Data were registered, and the trend of changes was descriptively discussed. Results: Out of ۳۶ patients (aged ۶۷±۸.۸ years), ۲۳ underwent at least two treatment cycles. Nineteen patients (۸۲.۶%) had bone metastases, ۱۲ (۵۲.۲%) had nodal metastases, ۵ (۲۱.۷%) had liver metastases, and ۳ (۱۳.۰%) had lung metastases. Eleven patients (۴۷.۸%) were considered responsive in the post-therapeutic scans, two of which experienced complete eradication of the metastatic sites.  Three patients (۱۳%) were categorized as progressive, and ۹ (۳۹.۱%) patients remained stable. Regarding mortality, nine patients died during the late follow-up (median of ۲۴ months). In the surviving population, ۶۵% reported no or mild pain in the final follow-up, based on a ۵-point scale pain assessment. Conclusion: The treatment of mCRPC patients with ۱۷۷Lu-PSMA-۶۱۷ may limit their disease progression and preserve their physical performance, which are important factors in their survival and quality of life.

Lutetium-۱۷۷, Prostate cancer, PSMA, Theranostic