Phase I Targeting Dominant Intraprostatic Lesion Using MR Spectroscopy and HDR Brachytherapy

Study Summary

This is a phase I study to evaluate the feasibility and safety of using MRI/MRS to identify the dominant intraprostatic lesion (DIL) and to selectively boost the lesion using inverse planned high dose rate (HDR) brachytherapy. The main objective is to exploit the ability of MRI/MRS to identify cancer regions within the prostate or the dominant intraprostatic lesions (DIL). The imaging data will be combined with the treatment planning CT images to define a treatment plan that will boost the dose delivered to the DIL up to 150% of the prescribed dose. Dose to the whole prostate and the dose delivered to adjacent organs will not change. This is accomplished by using inverse treatment planning software that can focus normally occurring high dose regions within the target volume to coincide with the DIL. After enrollment, each patient will have a MRI/MRS before starting treatment. Hormonal therapy and external beam radiotherapy will be given based on current standard of practice. During HDR brachytherapy, information about the location of tumor within the prostate will be used to design the brachytherapy treatment plan. We will try to increase dose to DIL by coincide existing high dose region on DIL using inverse planning software. Dose to prostate, and adjacent structure will remain the same as the current treatment practice. Timing and the delivery of brachytherapy will not change from our current practice. After the treatment, each patient will remain on study and follow for 12 months and treatment toxicity will be evaluated. A two-stage study design will be applied with a stopping rule for safety. Once a patient comes off study he will be routinely followed for disease outcome and any late toxicities.