A new study presented on March 13 at the European Association of Urology Congress in London reports that a PSMA PET/CT imaging test could safely reduce by half the number of people needing a biopsy for suspected prostate cancer after inconclusive or reassuring MRI results.
The findings from the PRIMARY2 trial are significant because they suggest a way to minimize invasive procedures for patients, potentially reducing discomfort and anxiety associated with prostate biopsies. The PSMA PET/CT scan works by using a molecule that binds to aggressive prostate cancer cells, making them visible as bright spots on the scan. This allows doctors to better distinguish between cancers that require treatment and those that are low-risk and unlikely to cause harm.
In current practice, men with suspected prostate cancer typically undergo an MRI scan first. If results are unclear or suspicious, a biopsy is performed to check for cancer cells. However, this routine procedure can be uncomfortable and carries risks of side effects. The PRIMARY2 trial recruited higher-risk individuals who had normal MRI results and randomly assigned them to receive either a standard biopsy or a PSMA PET/CT scan. The study found that those with negative or low-risk scans could avoid biopsy altogether, while those with positive scans underwent targeted biopsies based on the imaging results.
Dr James Buteau, nuclear medicine physician at Peter MacCallum Cancer Centre, said: "PSMA PET/CT scanning makes prostate cancer cells light up in a remarkable way, particularly in more aggressive cancers. It's rare to see such strong imaging that could be so powerful in the clinic. Incorporating this testing into clinical care could help to address the major challenge of prostate cancer overdiagnosis, which leads to at best unnecessary and at worst harmful treatment for cancers that would never cause any harm."
Professor Louise Emmett, Director of Theranostics and Nuclear Medicine at St Vincent's Hospital and co-leader of the study, said: "Getting told you have a risk of prostate cancer is a huge cause of anxiety and concern. Our findings show that PSMA PET/CT after MRI offers a 'belt and braces' approach that can determine which people have a clinically significant cancer, and which people are at low risk and don't need a biopsy or further testing. PRIMARY2 is the largest of a series of studies undertaken by this group, exploring whether PSMA PET/CT scanning could improve prostate cancer diagnosis and reduce unnecessary biopsies for patients."
Professor Dr Derya Tilki from Martini-Klinik Prostate Cancer Center in Germany said: "This well-conducted trial shows that incorporating PSMA PET/CT in men with low or intermediate risk lesions – defined by MRI as PI-RADS 2 or 3 – significantly reduced the number of unnecessary biopsies and the diagnosis of clinically insignificant prostate cancer. Importantly, this didn't compromise the detection of clinically significant disease. These results support consideration of PSMA PET/CT in the diagnostic work-up of appropriately selected patients. I congratulate the investigators on their study."
