A new study demonstrates that advanced imaging using prostate-specific membrane antigen (PSMA) PET/CT scans significantly improves the precision of treatment for men experiencing a recurrence of prostate cancer after surgery, potentially leading to better long-term outcomes and reduced unnecessary side effects. The five-year retrospective study, led by researchers at the UCLA Health Jonsson Comprehensive Cancer Center and published in the Journal of the National Comprehensive Cancer Network, provides compelling evidence for the integration of PSMA PET/CT into standard clinical practice.
The Challenge of Recurrence and Limitations of Traditional Imaging
Between 20% and 40% of men who undergo surgery for localized prostate cancer will experience a recurrence within ten years, often first indicated by a rising prostate-specific antigen (PSA) level. While radiation therapy is a common treatment to slow recurrence and improve survival, its effectiveness hinges on accurate staging – determining the extent of the cancer’s spread. Historically, this has been a significant challenge. Traditional imaging techniques, such as bone scans, CT scans, and MRI, often fail to detect small clusters of recurrent cancer, particularly when PSA levels are low.
This limitation frequently leads to broad-spectrum treatment, including radiation to the prostate bed and surrounding lymph nodes, and sometimes even hormone therapy, even when such aggressive intervention may not be warranted. The new research highlights the potential to move towards more personalized treatment plans based on a more accurate understanding of the disease’s location and extent.
How PSMA PET/CT Improves Detection
PSMA PET/CT utilizes a radioactive tracer that binds to prostate-specific membrane antigen (PSMA), a protein found on the surface of most prostate cancer cells. This allows clinicians to visualize even very small deposits of cancer that are invisible on conventional scans. Unlike traditional imaging, which primarily provides anatomical details, PSMA PET/CT offers functional imaging, revealing the biological activity of the cancer and improving the accuracy of staging. The scan can determine if the disease remains confined to the prostate bed, has spread to nearby lymph nodes, or has metastasized to other parts of the body.
Study Findings and Treatment Personalization
The UCLA-led study followed 113 men whose PSA levels rose after prostate cancer surgery. All patients underwent PSMA PET/CT scans prior to receiving radiation therapy, and their outcomes were tracked for a median of five years. The scan results directly informed treatment decisions, including whether to treat the entire pelvis or just the prostate bed, whether to add androgen deprivation therapy (ADT), and the appropriate radiation dosage.
Researchers found that approximately 60% of patients had detectable cancer on the PSMA PET/CT scans, with many exhibiting spread beyond the prostate bed to lymph nodes or bones. This allowed for adjustments to treatment strategies that would not have been possible with traditional imaging.
Key findings from the study include:
- Patients with visible cancer in the prostate bed or pelvic lymph nodes experienced the greatest benefit from whole-pelvis radiotherapy, which targets nearby lymph nodes in addition to the prostate bed.
- Patients whose scans revealed cancer in lymph nodes or distant sites demonstrated improved outcomes when androgen deprivation therapy (ADT) – a hormone therapy that suppresses testosterone – was incorporated into their treatment plan.
- Patients with no visible disease on the scans achieved the best outcomes with radiation therapy alone, suggesting that more aggressive interventions could be avoided in these cases.
- At the five-year mark, nearly all patients were still alive, and 72% showed no evidence of distant disease spread.
Implications for Patient Care and Clinical Guidelines
“PSMA PET/CT scans allow us to see exactly where cancer is and tailor treatment accordingly,” said Dr. Jeremie Calais, director of the clinical research program in the department of Nuclear Medicine and Theranostics, associate professor at the David Geffen School of Medicine at UCLA and senior author of the study. “Patients can get the therapy they need while avoiding unnecessary side effects, and even those with no visible disease can do very well with standard radiation.”
The study’s findings suggest a path towards more personalized care for men experiencing recurrent prostate cancer. Patients with limited disease may be spared the side effects of unnecessary hormone therapy, while those with more extensive disease can receive more targeted and effective treatment. The researchers emphasize that the information provided by PSMA PET/CT scans can guide critical decisions regarding the scope of radiation therapy and the potential need for ADT.
“This research underscores the value of incorporating PSMA PET/CT findings into clinical guidelines when deciding whether to add whole-pelvis radiation or hormone therapy to salvage radiation after prostate surgery,” said Dr. John Nikitas, a resident in the department of radiation oncology at UCLA Health, and first author of the study. “We also found that traditional measures such as PSA level were not strongly linked to long-term response, highlighting the importance of imaging-based, rather than PSA-based, decision-making.”
The increasing availability and utilization of PSMA PET/CT scans represent a significant advancement in the management of recurrent prostate cancer, offering the potential for improved outcomes and a higher quality of life for affected patients.
