Role of 3.0 T multiparametric MRI in local staging in prostate cancer and clinical implications for radiation oncology.

Purpose: To evaluate the accuracy of preoperative 3T multiparametric magnetic resonance imaging (3TmMRI) for local staging of prostate cancer and its influence on the decision to change the clinical target volume (CTV), total dose and hormonal therapy when treating prostate cancer patients with radiotherapy.

Methods: From 2009 to 2013, 150 patients, who had confirmed prostate cancer and underwent a 3TmMRI before treatment with radical prostatectomy or radical radiation therapy, were included. Radiation therapy treatment (CTV, total dose and hormonal therapy) was initially determined on the basis of the clinical information, and radiation therapy plan was reevaluated after 3TmMRI review. The value of preoperative 3TmMRI in local staging and in the decision of radiotherapy treatment according to NCCN risk classification was analyzed.

Results: 3TmMRI performed correct, over- and under staging in 78.7 % (37/47), 6.3 % (3/47), 14.8 % patients (7/47), respectively. 3TmMRI identified 6 cT2a, 7 cT2b, 28 cT2c, 3 cT3a, 3 cT3b tumors. At final pathology, 5 tumors were classified as pT2a, 5 as pT2b, 30 as pT2c, 4 as pT3a, 3 as pT3b. After reviewing the MRI reports, the initial radiotherapy and hormonal therapy plan was changed in 33.9 % patients (35/103).

Conclusions: In our group of patients, 3TmMRI has been a reliable technique providing an optimal staging for prostate cancer. Its routine use could induce important changes in radiation therapy treatments in a significant number of such patients. However, more additional studies are needed to clarify this issue.