Whole Body Bone Scan vs 18F-Choline PET/CT, Better Detection of Bone Metastases in Prostate Cancer Patients, PROSTAGE I

1. Introduction. Cancer of the prostate (PCa) is currently the leading newly diagnosed cancer and the second most common cause of cancer deaths among men in the industrialized world . In Denmark alone more than 4000 men are yearly diagnosed with PCa . As PCa primarily affects elderly patients, one can assume that PCa will become one of the most important medical issues in the developed world due to the already high incidence combined with a growing population of elderly men.

The aetiology of the disease is not well understood. In its most common form PCa evolves from the glandular tissue of the prostate. Metastatic spread will most commonly happen as lymphogenous spread to the regional lymph nodes or as haematogenous spread to the red bone marrow .

Intended curative treatment of PCa is associated with considerable side effects, in particular incontinence, impotence and radiation damage to the surrounding tissues. Furthermore, over 30% of patients with organ-confined disease, which was treated with radical prostatectomy, will have biochemical relapse within 10 years . Relapse may be due to local recurrent disease suggesting poor surgical quality or poor initial staging with undetected metastases at the time of treatment.

At diagnosis patients are stratified as having low, intermediary or high risk of dissieminatio according to D'Amico. Patients with intermediate or high risk of dissemination will be examined further with whole-body bone scintigraphy (WBS) and pelvic lymph node dissection (PLND). 2. Background. 2.1. Current staging and limitations. WBS has been the examination of choice for evaluation of potential dissemination to bone. WBS utilizes 99mTc-labeled methylene diphosphonate (99mTc-MDP) that binds to the bone matrix formed by the osteoblasts. Gamma cameras detect the γ-radiation emitted by the decaying tracer thereby creating a 2-dimentional image depicting local osteoblast activity .

Several limitations apply to the use of WBS in staging of patients with PCa. Sensitivity has reported as low as 39% in lesion-based analysis in patients with a low number of lesions . This combines with a low sensitivity due to many equivocal lesions caused by other bone pathology than metastasis.