Clinical trial could lead to new ‘gold standard’ test for detecting prostate cancer

A University of Alberta study shows that PET/CT imaging using a new tracing agent is more accurate in determining the extent of prostate cancer than current standard MRI for intermediate- and high-risk cases.

In research published this week in the journal JAMA OncologyThe researchers report that the new test correctly predicted tumor location and margin 45 percent of the time, nearly twice as often as the 28 percent rate for MRI.

“This is very important because we make a lot of treatment decisions based on where the cancer is in the prostate,” says Adam Kinnaird, assistant professor of surgery and adjunct assistant professor of oncology, as well as the Frank and Carla Sojonky Chair in Prostate Cancer Research and a member of the Northern Alberta Cancer Research Institute.

“If you have prostate removal and the cancer spreads outside the prostate, we widen our treatment margins a little bit so that we don’t leave any cancer behind. If you have prostate radiation, sometimes the radiation oncologist will do stimulation in the cancer center to better control the cancer,” Kinnaird says. “That imaging test gives us a better degree of precision to determine exactly where we need to treat.”

Potential new reference standard for testing

The test involves injecting a new prostate tumor-specific radioactive tracer called 18F-PSMA-1007 into patients’ bloodstream and then tracking it using a combination of positron emission tomography (PET) and computed tomography (CT) scans. Previous studies of PET/CT scans using other tracking agents haven’t been as useful, Kinnaird says.

The PET/CT and MRI scans were performed two weeks apart on 134 Alberta men who were about to undergo radical prostatectomy, a surgical procedure that removes the prostate, surrounding tissue and nearby lymph nodes. The accuracy of the tests’ predictions was then compared to the size and location of actual tumours later discovered by the surgeons.

“This clinical trial has big implications for clinical practice worldwide,” Kinnaird says, explaining that he expects PET/CT scanning using the new tracer will become the gold standard.

The test involves low radiation exposure, but Kinnaird says no patients in the study had any adverse effects. He expects the test will eventually replace other CT scans and bone scans currently required for prostate cancer patients, meaning fewer hospital visits, less waiting time for results and less radiation exposure for patients, but that will require further study.

“It would be very interesting if we could get more precise information and replace three tests with one, because these analyses are only available in Edmonton or Calgary,” says Patrick Albers, graduate researcher and co-author of the study.

The positive results from that trial have already prompted another clinical trial led by Kinnaird to determine whether PET/CT scanning can be used to guide ablation, a procedure that uses energy such as heat, cold or electricity to kill cancer cells in the prostate.

The new imaging agent is only available at a few treatment centres across the country pending Health Canada approval, but the Alberta government has just announced $3 million so 2,000 men can undergo the new tests in the meantime.

Ensuring Better Outcomes for Black Men

A second study recently published by Kinnaird’s research team shows that Black men with prostate cancer have similar outcomes to other men in Alberta. However, Black men are diagnosed an average of two years earlier, at age 64 rather than 66, leading Kinnaird to recommend that they be offered routine screening at age 45 rather than 50.

Published in Opening of the JAMA networkThe study used data from the Alberta Prostate Cancer Research Initiative (APCaRI), which Kinnaird chairs. A total of 6,534 men diagnosed with prostate cancer between 2014 and 2023 were included, including 177 who identified as Black. The study found that Black men were as likely to survive and not have metastases as the general patient population.

In the United States and the United Kingdom, other studies have shown that men of African and Caribbean origin have a twice the lifetime risk of developing prostate cancer than Caucasian men, suggesting a biological causality.

However, these countries have two-tier or primarily private health care systems, Kinnaird notes. The Alberta results, obtained in a publicly funded health care system, indicate that these differences in the U.K. and U.S. may be driven more by socioeconomic factors such as racism, poverty and limited access to health care than by genetics, he says.

The American Urology Association and the European Urology Association both recommend earlier screening for men of African descent and other high-risk populations, but Canadian guidelines do not. Kinnaird would like to see that change.

Kinnaird points to previous research from his team that shows Indigenous men get fewer prostate cancer screenings and have worse outcomes than others. He suspects this may be due to poorer access to health care for rural Albertans in general, but more study is needed.

“The problem is that if you can detect it early, localized and treatable, the cure rate is 95% or more. But if you wait until the cancer has metastasized, there is currently no cure,” he explains. “When it is detected late, it is a deadly disease.”