March 23 (UPI) -- Molecular imaging of prostate cancer tumors could transform how those with aggressive types of the disease are treated, a new study suggests.
The results of a trial involving 300 prostate cancer patients published Sunday by The Lancet found that a molecular imaging technique called PSMA PET/CT is more accurate than conventional medical imaging.
The method can detect levels of a molecule associated with the disease and determine the extent of its spread at the time of diagnosis. The authors of the report recommend the scans be introduced into routine clinical practice.
"Around one in three prostate cancer patients will experience a disease relapse after surgery or radiotherapy," co-author Declan Murphy, a professor at the Peter MacCallum Cancer Center in Australia, where the research was conducted, said in a press release. "This is partly because current medical imaging techniques often fail to detect when the cancer has spread, which means some men are not given the additional treatments they need. Our findings suggest PSMA-PET/CT could help identify these men sooner, so they get the most appropriate care."
Prostate cancer is commonly treated by surgery to remove the prostate or intensive radiotherapy targeting the tumor. If there is a high risk for spread, patients may be offered medical imaging -- typically CT and bone scans -- to help doctors determine if additional treatments are needed.
According to Murphy and his colleagues, PSMA PET/CT combines two imaging technologies -- positron emission tomography, or PET, and computed tomography, or CT. The researchers sought to investigate if the molecular imaging approach could help doctors better define the extent of disease at the time of diagnosis.
PSMA PET/CT involves giving patients a radioactive substance that detects a molecule called Prostate Specific Membrane Antigen, or PSMA, which is found at high levels on prostate cancer cells. They then undergo a PET/CT scan. The CT scan produces detailed images of the body's organs and structures, while the PET scan lights up areas where PSMA is present at high levels, indicating the presence of prostate cancer cells.
In the study, 300 men with prostate cancer at 10 hospitals across Australia received either conventional CT and bone scans or PSMA-PET/CT. Overall, the new approach proved to be 92 percent accurate in documenting the spread of cancer throughout the body, compared with only 65 percent accuracy with standard imaging, due in large part to its enhanced ability to detect small sites of tumor spread.
Indeed, conventional imaging failed to detect that cancer had spread in 29 patients, giving a false negative result. By comparison, PSMA-PET/CT gave false negative results in just six patients.
In addition, fewer men had false positive results with the new approach, and there were fewer inconclusive findings as well: 7 percent versus 23 percent. Both imaging techniques involve exposure to radiation but the dose associated with PSMA-PET/CT was less than half that with conventional imaging.
Finally, the authors noted that PSMA-PET/CT scans had more impact on the way disease was managed, with 28 percent having their treatment plans changed after the scans, compared with 15 percent following conventional imaging.
Although the study did not assess whether PSMA PET/CT scanning had any effect on patient survival, the researchers noted that the approach could improve outcomes by helping doctors determine whether to offer localized treatment, like surgery or radiotherapy, or to use more advanced treatments for the whole body if the cancer has already spread.
Costs associated with the technology vary by region, though, and the researchers caution that a full economic analysis will be critical for determining the feasibility of widespread use.
Nevertheless, they recommend a review of current clinical guidelines and for PSMA PET/CT to replace the use of conventional imaging where possible for men with high risk prostate cancer.
"Costs associated with PSMA-PET/CT vary in different regions of the world but this approach may offer savings over conventional imaging techniques," co-author Roslyn Francis, associate professor at the University of Western Australia, said. "A full health-economic analysis will help to determine the cost effectiveness of introducing PSMA-PET/CT, both from a patient and a healthcare perspective."
