Vessel Sparing Prostate Radiation Therapy

Vessel Sparing Prostate Radiation Therapy: Dose Limitation to Critical Erectile Structures (Corpus Cavernosum and Internal Pudendal Artery) by MRI Based Treatment Planning

Prostate cancer patients have a number of excellent treatment options to consider, and quality of life following treatment is often a consideration in treatment choice. One critical quality of life concern for patients diagnosed with prostate cancer is sexual function. Previous studies point to a vascular mechanism of impotence post-radiation therapy, as opposed to a nerve-based mechanism following surgery. In this study, the critical vascular structures (internal pudendal artery and corpus cavernosum) are defined by MRI-based imaging and included in treatment planning for radiation treatments, hopefully preserving critical artery function. This study will collect erectile function preservation rates at 5-years post-vessel-sparing radiotherapy with or without aids using the patient reported using the simplified three-question erectile function scale.

The vast majority of patients diagnosed with prostate cancer in the modern era of PSA screening have localized and potentially curable disease. Patients have a number of excellent treatment options to consider, and quality of life following treatment is often a consideration in treatment choice. One critical quality of life concern for patients diagnosed with prostate cancer is sexual function. Studies of sexual function post-radiation therapy fall into three categories: incidence studies; correlative (dose and toxicity) studies; mechanism(functional) studies. All these studies point to a vascular mechanism of impotence post-radiation therapy, as opposed to a nerve-based mechanism following surgery. In this study, the critical vascular structures (internal pudendal artery and corpus cavernosum) are defined by MRI-based imaging and included in treatment planning for radiation treatments. Investigators propose that this technique will improve quality of life, sexual function, and relapse-free survival.

This study's primary aim is to determine erectile function preservation rates at 5-years post-vessel-sparing radiotherapy with or without aids using the patient reported using the simplified three-question erectile function scale.

Inclusion Criteria:

• Histologically confirmed diagnosis of prostate cancer
• Patients must have measurable erectile function. Patients with erectile function on Viagra and drugs of the same class are eligible. Patients who require 6 months of hormonal therapy or less are eligible, provided baseline erectile function is measured prior to or within 14 days of the start of hormonal therapy.
• Baseline PSA (Prostate Specific Antigen), TNM stage (a classification of malignant tumors in cancer), and Gleason Score (A system of grading prostate cancer tissue based on how it looks under a microscope): Patients with low (PSA less than 10, T2a or less, Gleason 6 or less), intermediate, or high (Gleason 8-10, T3a, PSA over 20) risk disease are eligible for this protocol. Patients on finasteride or drugs of the same class are eligible.
• Patients must be 18 years or older. No upper age restriction.
• Patients treated with external beam radiotherapy alone or external beam therapy plus implant therapy are eligible.
• Patients must have an ECOG (Eastern Cooperative Oncology Group system of grading patient status that attempts to quantify cancer patients' general well-being and activities of daily life) performance status <2.
• The patient must sign study specific informed consent approved by the IRB of U of M indicating they are aware of the investigational nature of the treatment.

Exclusion Criteria:

• Patients who are impotent or have an IIEF (International Index of Erectile Function) <16.
• Patients who are medically ineligible for radiation therapy due to other medical conditions.
• Patients given hormonal therapy before baseline questionnaires filled out.
• Patients who receive implant only therapy.
• Patients unable to undergo MRI (Magnetic Resonance Imaging).