Milestone for landmark trial of less invasive prostate cancer diagnosis
03 September 2025
An Australia-wide clinical trial investigating a less invasive approach to diagnose early prostate cancer has reached a major milestone, successfully recruiting its 660th and final participant.
The PRIMARY2 trial, led by Peter Mac in partnership with St Vincent’s Hospital in Sydney, is testing whether men with suspected prostate cancer but uncertain findings on MRI scans can benefit from a new type of scan called a PSMA PET/CT scan.
Recruitment started in 2022 and the final patient has just been enrolled. The trial is assessing whether the next step should be a PSMA PET/CT scan rather than a prostate biopsy – an uncomfortable procedure.
“This Phase III clinical trial is assessing whether we can improve early diagnosis of prostate cancer, including safely avoiding biopsies without missing any prostate cancers,” says study Co-Lead Professor Michael Hofman.
“Only men with a positive PSMA PET/CT scan result would go on to have a biopsy, and this would be a targeted biopsy guided by their scan result.
“Men with a negative PSMA PET/CT scan result can avoid a biopsy altogether and instead be monitored,” says Prof Hofman, who is Director of the Prostate Cancer Theranostics and Imaging Centre of Excellence (ProsTIC) at Peter Mac.
Professor Louise Emmett, Study Co-Lead and Director of Theranostics and Nuclear Medicine at St Vincent's Hospital, says the trial has the potential to “reduce the number of men diagnosed with insignificant cancers that never progress and cause so much anxiety and over treatment”.
“The biggest thankyou goes to the 660 men who have joined the trial, as well as the dedicated urology and nuclear medicine teams at our participating sites across Australia,” Professor Emmett says.
Peter Mac’s Associate Professor Daniel Moon, Urology lead on PRIMARY2, adds the trial was an “example of an outstanding Australia-wide collaboration”.
“What a privilege to be part of a world class team completing recruitment for a world-first trial that aims to advance the diagnosis of prostate cancer in men,” Associate Professor Moon says.
The other recruitment sites were Royal Brisbane and Women’s Hospital, Royal Adelaide Hospital, Royal Darwin Hospital and, in Melbourne, Austin Health and Cabrini Health.
Trial participants are monitored for up to two years, with first results expected in 2026.
The trial was funded by the U.S. Prostate Cancer Foundation, St Vincent's Curran Foundation, ANZUP (Australian and New Zealand Urogenital and Prostate) Cancer Trials Group, and the National Health and Medical Research Council (NHMRC).
Read more about the trial here: PSMA PET Additive Value for Prostate Cancer Diagnosis in Men With Negative/Equivocal MRI
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About Peter Mac
Peter MacCallum Cancer Centre is a world leading cancer research, education and treatment centre and Australia’s only public health service dedicated to caring for people affected by cancer.