BERKELEY, CA (UroToday.com) - Bone metastases are a frequent complication in patients affected by advanced prostate cancer (PCa).[1] Bone scan (BS) is usually performed in order to evaluate the presence of disease localizations in the bone. However this method presents an important limitation with a low detection rate (only 1%-13%) in patients with PSAv <20 ng/mL and Gleason score <8. In fact some authors affirm that there is not a real indication to perform BS in patients with ‘relatively low’ PSA levels (<10 ng/mL), without skeletal symptoms and in the absence of risk factors (high T stage or Gleason score).[2] It has been suggested[3] that a pathological bone lesion begins as bone marrow involvement only, without a skeletal alteration. This interval time could represent a crucial point in the treatment planning of the patient.
In this field an important question arises: “Could 11C-choline PET/CT have a role in filling this gap”? Our study tried to answer this question. We enrolled 123 consecutive PCa patients with a negative BS after radical prostatectomy (RP) and a biochemical relapse, with low PSA values (mean PSA value 3.3ng/mL; range 0.2-25.5). We compared 11C-choline PET/CT results obtained within 4 months from BS (range: 1 day to 4 months; mean: 2.5 months). 11C-choline PET/CT was positive in 42 patients (34.1%). In particular, it detected pathologic lesions in bone (10 patients), lymph nodes (20 patients), bone and lymph nodes (7 patients), bone and lung (1 patient), lymph nodes and lung (1 patient), and prostatic fossa (3 patients). In comparison with BS, 11C-choline PET/CT showed a total of 30 unknown bone lesions in 18/123 patients (14.6%). Ten of the 30 lesions detected by 11C-choline PET/CT were located in the bone marrow, without any alterations at CT images, also confirming the theory stated above.[3] The reason for the better sensitivity of 11C-choline could be: 1) the different uptake mechanism of the two tracers: the uptake of 99mTc-DPD is related to the osteoblastic activity of the lesion, consequently it represents an indirect sign of the presence of metastases, while the uptake of 11C-choline directly accumulates in the metastatic lesions. This hypothesis could justified the earlier identification of metastases by 11C-choline, or 2) the much higher quality of PET/CT images, a significant advantage over BS.
11C-choline PET/CT could represent a new and important option in the diagnostic flow chart of PCa patients. According to our findings and the promising results of the literature, we can suggest that in case of biochemical relapse after radical prostatectomy, patients presenting with high PSA should undergo a BS as first approach, while in the case of low PSA, 11C-choline PET/CT could represent the first step in the re-staging of the disease.
References:
- R.E. Coleman. Metastatic bone disease: clinical features, pathophysiology and treatment. Cancer Treatment Reviews, 27 (2001), pp 165-176.
- L.F. Wymenga, J.H. Boomsma, K. Groenier, D.A. Piers, H.J. Mensink. Routine bone scans in patients with prostate cancer related to serum prostate-specific antigen and alkaline phosphatase. BJU International, 88 (2001), pp. 226-230.
- M. Beheshti, R. Vali, P. Waldenberger et al. The use of F-18 choline PET in the assessment of bone metastases in prostate cancer: correlation with morphological changes on CT. Molecular Imaging Biology, 12 (2010), pp. 98-107. Erratum in: Mol. Imaging Biol. 2010 Jun; 12:360.
Written by:
Chiara Fuccio, MD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Nuclear Medicine Unit, Department of Hematology Oncology and Laboratory Medicine, Azienda Ospedaliero – Universitaria di Bologna Policlinico Sant’Orsola – Malpighi, University of Bologna, Bologna, Italy.
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