Should 18F-fluciclovine-PET/CT be included into the decision-making process for radiotherapy after surgery for prostate cancer?

This study evaluated the role of ¹⁸F-fluciclovine-PET-CT versus conventional imaging (bone scan and either CT or MRI) alone for salvage radiotherapy (RT) after prostate surgery for the treatment of patients with localized prostate cancer (PCa). The data showed that including ¹⁸F-fluciclovine-PET-CT into the decision-making process for RT after surgery significantly improved survival without recurrence for these patients.

Localized PCa is a form of cancer that has not spread beyond the prostate gland. It can be treated by surgery, radiation, or hormone therapy. Radical prostatectomy (RP) surgically removes the prostate and the surrounding tissues in patients with localized PCa. Almost 15-40% of men who undergo RP as a treatment for localized PCa experience biochemical recurrence (BCR). BCR is a rise in the blood level of prostate-specific antigen (PSA; a protein made by cells of the prostate gland) after treatment with surgery. Salvage RT is usually performed after RP to prevent BCR.

BCR may indicate a recurrence of the disease but does not provide tumor location. In order to localize the tumor, an imaging scan (CT, MRI, or PET-CT) can be performed.

A tracer is an injected (intravenous) radioactive material used to intensify tumor signals during PET-CT scans, thereby exposing and locating them. ¹⁸F-fluciclovine is a PET-CT tracer and has been increasingly used to localize disease in men with suspected BCR of PCa after previous treatment. However, studies evaluating the role of ¹⁸F-fluciclovine-PET-CT in improving cancer control compared with conventional imaging alone for salvage RT after RP remain under investigation.

The study involved 165 patients with localized PCa that received RP. All patients had detectable PSA levels after surgery (BCR) and negative findings on conventional imaging scans (bone scans and CT/MRI). Patients were randomly assigned into 2 groups. Group 1 included 82 patients who underwent conventional imaging only. Group 2 included 83 patients who underwent conventional imaging plus ¹⁸F-fluciclovine-PET-CT. The average follow-up time was 3.52 years.

After 3 years, 63% of the patients in group 1 were alive without events such as BCR or PSA persistence compared to 75.5% of the patients in group 2. Patients in group 1 were 2.04 times more likely to experience events such as BCR or PSA persistence than patients in group 2.

The most common side effects were late urinary frequency or urgency, and diarrhea in both groups.

This study concluded that including ¹⁸F-fluciclovine-PET-CT into the decision-making process for RT after surgery significantly improved survival without any biochemical recurrence or PSA persistence for patients with localized PCa.

The sample size of the study was small. This study was sponsored by Blue Earth Diagnostics, the manufacturers of ¹⁸F-fluciclovine. Integration of novel PET radiotracers into the RT decision-making process needs further studies.