Could Whole Body MRI Change Staging for Patients Affected by High Risk Prostate Cancer Candidate to Local Radiation Therapy?

Abstract

The purpose of our experience is to understand if Whole Body MRI (WBMRI) could be useful in identifying bone metastasis in patients affected by high risk prostatic adenocarcinoma with negative bone scan (BS) so as to avoid a local radiotherapy anticipating the proper systemic treatment. Routinely we use multiparametric pelvic MRI in patients undergoing to local radiotherapy to better identify volumes to be treated. In high risk patients we extended the MRI study to whole body to obtain a more accurate staging. Between 1/1/2016 and 21/3/2016, we evaluated 34 patients, with diagnosis of high risk (PSA ≥ 20 ng/ml or G-S ≥ 8 or cT3-4) prostatic adenocarcinoma (median age 69, range 48-63), of which 17 underwent to surgery, 1 to trans urethral resection of the prostate (TURP) and 16 to prostatic biopsy, sent to our ambulatory to evaluate an adjuvant or definitive radiotherapy. All patients had a negative BS for the standard staging of disease and then they underwent to WBRMI to compare the data on the M parameter. We used an 1.5 T MRI scan performing T1, T2, DWI and STIR (sagittal coronal or axial depending on the district) images with and without m.d.c. Bone metastases were detected at WBMRI in 6 (18%) patients. All of them were positive on assile skeleton (vertebrae or pelvis). Considering the six patients positive for bone metastasis, 3 of them could be considered oligometastatic (not more than 2 bone metastasis) and 3 had more than 2 bone sites involved. Local radiotherapy was not performed for all the six metastatic patients and was administered a systemic treatment (hormonal therapy or chemotherapy). Despite the exiguous number of patients, WBRMI seems to be a valid method to identify patients, among high risk ones, who are affected by bone metastasis and are not suitable for local, definitive treatment. The value of 18% of patients with negative bone scan and positive WBMRI for bone metastasis, seems to be confirmed in patients just seen after our observation but indeed we need a larger number of patients to confirm this result.