PET-based radiotracers appear to be successful in the treatment of metastatic prostate cancer
Local therapies using stereotactic ablative radiation (SABR) are increasingly being used to treat patients with oligometastatic disease (only a few metastases) due to the accumulating evidence regarding its efficacy in improving oncologic outcomes. In patients with prostate cancer, there is additional interest in using SABR to avoid or delay treatment with androgen deprivation therapy (ADT, or hormonal therapy). A question in the field is how to approach a state in which a tumor progresses at a few sites (usually 1-5 sites) while other sites remain stable or continue to respond to systemic therapy. This is called oligoprogressive disease. This study retrospectively examined the outcomes of using serial SABR for oligoprogressive metastatic cancer. Data from 25 patients undergoing repeat stereotactic body radiation therapy (SBRT) for PET-avid oligometastatic prostate cancer (1-5 lesions). After treatment with SBRT, 16 patients (64%) had a PSA level decline of greater than 50%. The median delay in using or intensifying hormonal therapy was about 2 years. From the first SBRT to the last follow-up, 7 patients (28%) remained off ADT therapy.
Thus, SABR appears to be associated with high rates of PSA response and delays cancer progression. More research is needed in prospective studies with larger numbers of patients.
Urology. December 14, 2022.