C-choline PET scans detect site of recurrence in prostate cancer patients after EBRT
MedWire News: Researchers have found that C-choline positron emission tomography (PET) is a viable method for identifying sites of cancer recurrence among prostate cancer patients with biochemical recurrence (BCR) after external-beam radiotherapy.
The study was prompted by the inability of a raised prostate-specific antigen (PSA) levels, the standard indicator for BCR, to distinguish between loco-regional recurrences and the presence of distant metastasis.
“C-choline PET scan is a sensitive and accurate imaging technique to identify the site of recurrence in patients with PSA relapse after EBRT,” report Anthonius Breeuwsma from the University of Groningen in The Netherlands, and colleagues in the International Journal of Radiation Oncology Biology Physics.
The team performed C-choline PET scans on 70 patients with a median PSA level of 10.7 ng/ml (indicating BCR) after undergoing EBRT. They compared the results with 10 EBRT-treated prostate cancer patients without BCR.
A total of 57 patients with BCR proved “true positives” (confirmed by prostate biopsy, additional imaging studies [including transrectal ultrasound, bone scan, and magnetic resonance imaging of the prostate], and response to salvage therapy) after the C-choline PET scan. This translated to an 81% sensitivity rate.
None of the 10 control patients scans showed any lesions.
Possible sites of recurrence evaluated included the prostate, the pelvic lymph nodes, and the skeleton. A total of 41 out of the 57 BCR patients with positive scans had only local recurrence, which was confirmed by biopsy in 26 cases. A further 16 of the 57 patients had loco-regional and/or distant recurrence identified.
The six patients who showed bone metastases on their C-choline PET scan had their results confirmed by further bone scanning.
“This implies that whole-body PET scan may be the best goal-approached method in prostate cancer patients with suspicion of recurrent disease,” suggest Breeuwsma and team.
They report the overall positive and negative predictive values for C-choline PET scan as 1.0 and 0.44, respectively.
The research team also notes that one of the main concerns about the C-choline PET scan is sensitivity among patients with very minimal recurrence, expressed by a very low PSA level. However, their results indicate an 80% sensitivity in patients with a serum PSA below 4 ng/ml.
They conclude: “With the improvement and increased clinical use of local salvage therapies such as cryoablation and high-intensity focused ultrasound, restaging of prostate cancer after EBRT has become an important issue.”
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010
By Sarah Guy