PET-Enhanced MRI is “Best Available Test” to Guide Recurrent Prostate Cancer Treatment

October 27, 2020
Whitney J. Palmer

Adding the 18F radiotracer to MRI scans provides more detail, leading to better treatment planning and better disease-free survival rates in men with recurrent prostate cancer.

Integrating advanced PET into imaging for patients who have recurrent prostate cancer can not only impact treatment plans, but it can also improve their disease-free survival rates, according to new research presented Monday.

During the American Society for Radiation Oncology annual meeting, investigators from the Winship Cancer Institute of Emory University shared the results of their EMPIRE-1 (Emory Molecular Prostate Imaging for Radiotherapy Enhancement) trial that determined adding the PET radiotracer fluciclovine to conventional imaging significantly benefits patients.

Overall, the team determined that among patients whose prostate cancer returned after prostatectomy, more than 75 percent of those who used the PET molecular to help guide their treatment were still disease-free three years later. This increased survival rate was sustained for four years, the team said.

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“The decision to offer post-prostatectomy radiation therapy is complex, because conventional imaging can leave unanswered questions on the best approach to treatment planning,” said co-principal investigator Ashesh B. Jani, M.D., radiation oncology professor in the Winship Cancer Institute. “What this research has found is that integrating advanced molecular imaging into the treatment planning process allow us to do a better job of selecting patients for radiation therapy, guiding radiation treatment decisions and planning and ultimately, keeping patients’ cancer under control.”

With one in nine men developing prostate cancer during their lives, this disease is the leading cause of cancer death among American men. Even after radical prostatectomy, between 20 percent and 40 percent of men can experience a recurrence, signaling that they have an aggressive form of the disease. In these cases, providers typically use conventional imaging techniques, including CT and MRI, to guide radiation therapy decisions, but MRI with PET has been shown to more accurately detect the presence and location of developing tumors.

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To determine the impact on fluciclovine (18F), a radiotracer that received U.S. Food & Drug Administration approval halfway through a trial in 2016, the team, also led by David M. Schuster, M.D., a nuclear radiology specialist and professor at Emory, enrolled 165 patients who had undergone radical prostatectomies in their EMPIRE-1 trial. All patients, who had abnormal prostate specific antigen (PSA) levels had CT and MRI for initial treatment planning. The team, then, divided participants into two groups – one that received radiation therapy based on conventional imaging alone and a second group that underwent 18F PET scans and received treatment guided by those additional findings.

Based on a three-year follow-up, the team determined that patients who had advanced imaging-guided radiation therapy had a higher disease-free survival rate than those with therapy guided by conventional imaging along – 75.5 percent versus 51 percent, respectively. There were no significant differences in provider-reported severe genitourinary or gastrointestinal side effects reported in either treatment group.

“At three years, the group getting treatment guided by PET fluciclovine had a 12-percent better cancer control rate, and this persisted at four years, as well, with a 24 percent-improvement,” Jani said. “We think the improvement was seen because the novel PET allowed for better selection of patients for radiation, better treatment decisions, and better radiation target design.”

Based on these results, the team said, 18F, which had not been widely integrated into prostate cancer treatment planning, should be integrated into therapeutic planning. And, it is possible that an even more effective radiotracer could be around the corner, they said.

“Fluciclovine PET has become the best available test,” Schuster said. “But, now there’s an even newer kid on the block. In EMPIRE-2, we’re building on the results of EMPIRE-1 by comparing PSMA with fluciclovine to see which one of these radiotracers improves cancer control better.”

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