18F-choline PET/CT detects PCa recurrences early

Three out of four patients with prostate cancer with an 18F-choline positron emission tomography/computed tomography–detected recurrence were potentially salvageable with local therapy or metastasis-directed therapy (MDT), according to results of the screening phase of the phase II STOMP randomized trial.

Dr. Ost“The majority of prostate cancer recurrences are eligible for local therapies and should not be considered palliative,” first author Piet Ost, MD, PhD, radiation oncologist and senior clinical investigator of the Research Foundation, Flanders, Belgium, told Urology Times. Findings were presented at the Genitourinary Cancers Symposium in Orlando, FL.

According to Dr. Ost, with the introduction of choline and prostate-specific membrane antigen PET-CT, clinicians are seeing prostate cancer recurrences earlier, at the first signs of PSA relapse.

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“Many of these recurrences are limited in number and location, called oligorecurrences. More aggressive local therapies-metastasis-directed therapy-have been suggested for these recurrences instead of systemic treatment, but it is unclear from literature what the proportion of oligorecurrent patients is,” Dr. Ost said.

The current study aimed to describe the anatomic patterns of prostate cancer recurrence after local therapy and reports the proportion of patients potentially eligible for MDT, defined here as those patients with up to three metastatic lesions.

The trial included 229 patients who underwent 18F-choline PET/CT for biochemical prostate cancer recurrence for potential inclusion in the randomized STOMP trial. In STOMP, patients will be randomly assigned to active surveillance or MDT. Eligible patients included those with biochemical recurrence, up to three extracranial metastases, and testosterone greater than 50 ng/mL.

Based on the screening, patterns of recurrence were classified as local (prostate or prostate bed), distant (N1 or M1b/b/c), or a combination of both.

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After screening, the authors identified 208 patients (91%) with a recurrence and 21 patients (9%) with no recurrence. Of those men with recurrence, 10% had a local recurrence and 81% had a distant recurrence. The most common site of recurrence was the lymph nodes (30%), followed by the prostate (11%), bone (18%), and visceral metastases (4%), or a combination of these sites (37%).

Among the patients with distant recurrence, 57% were considered oligorecurrent: 25% of patients had one lesion, 17% had two lesions, and 15% had three lesions.

Seventy-four percent of the patients were considered to have salvageable disease (three or fewer metastases). Patients with salvageable disease had lower PSA levels (p=.003) and lower PSA doubling time (p<.001) compared with patients with non-salvageable disease. Twenty-seven percent of men with oligorecurrent prostate cancer agreed to be randomized in the STOMP trial.

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Based on the results of this study, Dr. Ost said, “Early screening with 18F-choline PET-CT is able to detect clinical recurrences early and identifies patients eligible for metastasis-directed therapy.”

Dr. Ost is a consultant/adviser for Ferring and has received travel, accommodations, and expenses from Ferring and Ipsen. His institution has received research funding from Ferring, Merck, and Novartis.

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