Implementation of advanced imaging techniques like multiparametric magnetic resonance imaging (mpMRI) or Positron Emission Tomography (PET) in radiation therapy (RT) planning of patients with primary prostate cancer demands several preconditions: accurate staging of the extraprostatic and intraprostatic tumor mass, robust delineation of the intraprostatic gross tumor volume (GTV) and a reproducible characterization of the prostate cancer's biological properties. In the current review we searched for the currently available imaging techniques and we discussed their ability to fulfill these preconditions. We found that current pretreatment imaging was mainly performed with mpMRI and/or Prostate-specific membrane antigen PET imaging. Both techniques offered an accurate detection of the extraprostatic and intraprostatic tumor burden and had a major impact on RT concepts. However, some studies postulated that mpMRI and PSMA PET had complementary information for intraprostatic GTV detection. Moreover, interobserver differences for intraprostatic tumor delineation based on mpMRI were observed. It is currently unclear whether PET based GTV delineation underlies also interobserver heterogeneity. Further research is warranted to answer whether multimodal imaging is able to visualize biological processes related to prostate cancer pathophysiology and radiation resistance.

The combined treatment of tumors with implanted low-dose-rate iodine seeds and external beam irradiation can decrease the total dose of the external beam irradiation and, hence, offer the possibility of considerable dose sparing of normal tissues without compromising local tumor control rates.

therapy to the prostate compared to 5.6 years for patients who did receive radiation therapy to the prostate. Conclusion: Similar to newly diagnosed metastatic prostate cancer with a low metastatic burden limited to the bone, M1a prostate cancer may also derive a significant overall survival benefit from receiving radiation therapy to the primary prostate tumor. The use of prostate-directed radiation therapy for M1a patients should be further investigated.