Prognostic qualities of 18F-choline PET/CT in high-risk prostate cancer patients

¹⁸F-choline uptake on a positron emission tomography/computed tomography (PET/CT) is a prognostic indicator for biochemical recurrence, bone metastasis, and death for high-risk prostate cancer patients, according to a Swedish study published online August 7 in the European Journal of Hybrid Imaging.

Researchers from Sahlgrenska University Hospital in Göteborb had conducted a prior study which showed that ¹⁸F-choline PET/CT had a very high specificity of identifying regional lymph node metastasis in patients who had undergone radical prostatectomy and/or radiation therapy. They hypothesized that these patients who had a choline uptake on PET/CT suggestive of metastasis would have a worse prognosis.

The patient cohort included 124 men who had a negative or inconclusive bone scan, 28% of whom had undergone a radical prostatectomy and 96% of whom had received radiation therapy. The majority had clinical tumor stage T3 (41%) or T2 (36%). ¹⁸F-choline PET/CT exams were negative for 78%, with 12% having inconclusive exams and 10% having positive ones.

The patients were followed for a minimum of five years, and a median of 75 months. Nearly one-fourth (24%) experienced a biochemical occurrence, 5% were diagnosed with skeletal metastases, and three patients died from prostate cancer. The authors reported that of the 97 men who had a negative PET/CT scan, two developed skeletal metastases and 18 had a recurrence.

Twelve patients had a positive PET/CT. Cancer-free survival was much shorter for these patients, 49% at five years compared to 62% for patients with an inconclusive exam and 82% for men with a negative exam. The time to develop distant skeletal metastasis within five years was also shorter, at 83% compared to 100% for men with negative and inconclusive scans.

“PET/CT findings were the only significant predictor of biochemical recurrence and of skeletal metastasis,” the authors wrote. “Our results imply that the positive predictive value of choline uptake on PET/CT findings is high, not only in regional lymph nodes as previously reported, but also in non-regional lymph nodes and distant metastasis. This could help make informed decisions for men with positive choline PET/CT findings, especially in cases with more than one uptake site.”

“In men with a newly diagnosed high-risk prostate cancer and a negative or inconclusive bone scan, ¹⁸F-choline uptake on PET/CT suggestive of metastasis was associated with recurrence, progression to distant metastasis, and prostate cancer death. This strongly indicates that choline uptakes represented metastasis and not false positive findings, “ concluded lead author Henrik Kjölhede, MD, and colleagues concluded.

REFERENCE

1. Kjölhede H, Almquist H, Lyttkens K, et al. Pre-treatment ¹⁸F-choline PET/CT is prognostic for biochemical recurrence, development of bone metastasis, and cancer specific mortality following radical local therapy of high-risk prostate cancer.  Eur J Hybrid Imaging. 2018;2(1):16.