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Intensity Modulated Radiation Therapy for Prostate Cancer

San Francisco, CA, USA

Study Description

-This study represents a progression from findings in four previous National Cancer Institute (NCI) Radiation Oncology Branch (ROB) protocols (02-C-0167A, 02-C-0207E, 03-C-0190B, 04-C-0171). In these previous works we have begun to develop techniques to obtain Magnetic Resonance (MR) biological images and co-register tissue in prostate cancer patients.

-The primary objective of the first portion of this study is to assess the feasibility of using Intensity-modulated radiation therapy (IMRT) to treat the at-risk lymph nodes in prostate cancer. Also, if feasible, we hope optimize this technique with experience.

-This is a study of image guided, targeted radiation therapy in patients with high risk of nodal metastases from prostate cancer. Patients with prostate cancer who have more than 15% risk of lymph node (as defined by the Partin tables) metastasis will be eligible for this study.

On the first 10 patients, we will perform approximately 5 computed tomography (CT) simulations throughout the course of their therapy. On each simulation, the initial treatment plan will be re-run. The dose-volume data from target and normal tissues will then be re-analyzed. From this analysis we will be better able to determine the size of margins needed to account for organ motion and changes such as varying amounts of gas in the bowel and fluid in the bladder. To the best of our knowledge, no such analyses have been published.
If the initial part of this trial is feasible, we will proceed to a phase I dose escalation trial of radiation to the at-risk lymph nodes. The primary statistical objective of the phase I portion of this study is to estimate the Maximum Tolerated Dose (MTD) of external beam radiation based on evaluating acute toxicity. The study will be conducted with a dose-escalation design with 3 patients in each dose cohort. If fewer than 2 of 3 patients experience an acute dose limiting toxicity (DLT) than patients will be accrued to the next dose cohort. If 2 or more of 3 patients experience a DLT then the MTD will be exceeded and the prior, lower dose cohort will be considered the MTD. Secondary objectives of this study are to relate patterns in gene and protein expression to response and toxicity and to evaluate the frequency of late term toxicity.
Specific procedures and risks will be described in a separate consent to be obtained at the time of biopsy. Tissue samples will be processed for complementary deoxyribonucleic acid (cDNA) microarray testing and stored for future analysis in the Radiation Oncology Branch, NCI.
Anatomic Magnetic Resonance Imaging (MRI) and magnetic resonance (MR) biological images of the prostate and pelvis will be obtained and tissue will be acquired with biopsy locations precisely translated (co-registered) to an MR image of reference. A fiducial marker (gold seed) will be left at the biopsy site as a fiducial marker to direct future radiation therapy to the prostate. If necessary, additional fiducial markers will be placed for prostate localization during treatment.


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