Switching to a more advanced imaging technique can improve detection, disease staging, and tailoring of treatment in patients with aggressive prostate cancer, according to industry experts.
In a new study, published March 22 in Lancet, led by Michael S. Hofman, MBBS, with the Peter MacCallum Cancer Center in Australia, investigators determined using a molecular imaging technique, known as PSMA PET/CT, does a better job at identifying molecules associated with prostate cancer and in determining how much the disease has already spread at the time of diagnosis. And, it reaches this goal with less than half the radiation dose – 8.4 mSv vs. 19.2 mSv, respectively.
“Taken together, our findings indicate that PSMA-PET/CT scans offer greater accuracy than conventional imaging and can better inform treatment decisions,” Hoffman said in a press statement. “We recommend that clinical guidelines should be updated to include PSMA-PET/CT as part of the diagnostic pathway for men with high-risk prostate cancer.”
With this technique, patients were given a radioactive substance that detects Prostate Specific Membrane Antigen (PSMA), high levels of which are found in prostate cancer cells. Then, they underwent a PET/CT scan – the CT produced detailed images of body organs and structures while the PET lit up where PSMA was present in high quantities.
While the study didn’t look at whether using molecular imaging could actually impact patient survival, the results, he said, could help doctors determine whether to use localized treatment, such as surgery or radiotherapy, or more advanced treatments that would affect the patient’s entire body.
What the Study Found
To determine the efficacy of PSMA-PET/CT, investigators divided 300 men into two groups – 152 received conventional CT and bone scans, and 148 received PSMA-PET/CT. They, then, swapped and received the alternate form of scanning unless they had more than three metastases on their initial scan.
Based on results PSMA-PET/CT proved to be almost one-third more accurate in identifying the spread of prostate cancer throughout a patient’s body. The molecular imaging was 92-percent accurate versus 65-percent accuracy with standard imaging. Not only was PSMA-PET/CT better at detecting small sites of tumor spread, but it also provided false negatives in only six cases. In contrast, conventional imaging failed to detect metastasis in 29 patients.
Impact on Treatment
In addition to improving detection, PSMA-PET/CT also had a significant impact on a patient’s treatment plan and disease management. According to senior author Declan Murphy, the effect could be greatly beneficial.
“Around one in three prostate cancer patients will experience a disease relapse after surgery or radiotherapy. 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,” he said. “Our findings suggest PSMA-PET/CT could help identify these men sooner, so they get the most appropriate care.”
According to the study results, treatment plans were changed in 28 percent of men who received PSMA-PET/CT. Only 15 percent of men with conventional imaging saw any alterations in their care plan. The effect remained even when PSMA-PET/CT was used as a second-round screening – 27 percent of patients had treatment plan changes after additional PSMA-PET/CT imaging, and only 5 percent saw changes with conventional imaging.