Introduction
In the past few years, the FDA approved two significant tools for the management of prostate cancer patients. The first is 68Gallium-PSMA PET/CT, which was approved in December 2020(1). It is a highly accurate whole-body diagnostic scan that detects prostate cancer metastasis throughout the body with much greater accuracy compared to previously used standard of care exams (bone scan plus CT abdomen and pelvis), leading to a change in management in many patients(2).The second is a new radioactive therapy for prostate cancer patients named 177Lutetium-PSMA, which was approved in March 2022(3). This radioactive tracer is injected intravenously, then it targets and destroys metastatic cancer cells throughout the body. The results of the VISION trial showed that patients receiving 177Lu-PSMA had extended survival, a better quality of life with a decrease in body pains, and low side effects(4).
Real case example from our Theranostics unit
Patient history
We present a 74-year-old patient with metastatic hormone-resistant prostate cancer, post-hormonal therapy (Abiraterone), and chemotherapy (Docetaxel).
Pre-therapy scan
His baseline 68Ga-PSMA PET/CT scan (Fig.1) showed diffuse metastatic lymph nodes and bony lesions with high PSMA uptake, making the patient eligible for the therapy.
Teaching point 1
68Ga-PSMA PET/CT scan is a whole-body imaging tool to detect all sites of cancer prostate deposits in a single exam. (Local recurrence, nodal, bony and visceral deposits)
The procedure
• The patient received two intravenous therapeutic doses of 177Lutetium-PSMA (separated by 2 months).
• The images in (Fig. 2) show anterior and posterior SPECT views, 5 hours after the injection of the first dose of 177Lutetium-PSMA, showing good accumulation of tracer in tumor cells with the same tumoral distribution as pre-therapy PSMA-PET/CT.
Teaching point 2
177Lutetium emits low amount of Gamma rays that can be imaged using a SPECT machine, to confirm delivery of therapeutic drug to target tumor cells.
Post-therapy
• Follow up 68Ga-PSMA PET/CT after 6 months (Fig.3) shows resolution of the metastatic lymph nodes and marked regression of the metastatic bony lesions.
• The tumor marker level (PSA) decreased 94%, from 283ng/ml before therapy to 18ng/ml.
• The patient now has marked improvement in quality of life with resolution of his bony pains. He is able to perform his daily activities back normally.
Teaching point 3
177Lutetium-PSMA is a radioactive therapy for metastatic cancer prostate patients. It prolongs survival, leads to marked improvement in quality of life and with low side effects.