Clinical Trial Comparing 3-D RT vs. IMRT in Post- Prostatectomy Prostate Cancer Patients

INCLUSION Criteria: Subjects must meet all of the inclusion criteria to participate in this study. * Histologically documented adenocarcinoma of the prostate. * Status post radical prostatectomy with sampling of the pelvic lymph nodes with histologically confirmed adenocarcinoma of the prostate, with the patients falling into either the "adjuvant low or high risk groups" or the "salvage low or high risk groups" as indicated below. In those cases where patients undergo a prostatectomy without any sampling of the pelvic lymph nodes, patients will be also considered eligible if they are found to have a negative pelvic CT or MRI scan which shows no evidence of lymphatic nodal metastases after the prostatectomy. * "Adjuvant High Risk Group" are those patients with an undetectable or persistent/decreasing PSA levels (before starting therapy) who MUST be able to start radiation therapy treatments within 6 months of radical prostatectomy with at least ONE of the 3 disease features: * Pathologic T2N0 (with no clinical evidence of metastases) and Gleason Score ≥ 8 * Pathologic T3aN0 (with no clinical evidence of metastases) with Extra-Capsular Extension and Gleason Score ≥ 8 * Pathologic T3bN0 (with no clinical evidence of metastases) with any Gleason Score * "Salvage High Risk Group" are those patients who experience a PSA failure (defined as at least 1 detectable PSA level \> 0.2 ng/ml or at least 2 consecutive increases in PSA levels over baseline which are at least 1 month apart after radical prostatectomy) with at least ONE of the 4 following features: * Pathologic T3bN0 disease (with no clinical evidence of metastases), * Pathologic T2-3aN0 disease (with no clinical evidence of metastases) with Gleason Score ≥ 8, * Pathologic T2-3aN0 disease (with no clinical evidence of metastases) with PSA Doubling Time ≤ 10 months, * Pathologic T2-3aN0disease (with no clinical evidence of metastases) with Pre-RT PSA level ≥ 1.0 ng/ml * "Adjuvant Low Risk Group" are those patients with an undetectable or persistent/decreasing PSA levels (before starting therapy) who MUST be able to start radiation therapy treatments within 6 months of radical prostatectomy with at least ONE of the 2 disease features: * Pathologic T2N0 (with no clinical evidence of metastases), Gleason Score ≤ 7, with positive margins * Pathologic T3aN0 (with no clinical evidence of metastases) with Extra-Capsular Extension, Gleason Score ≤ 7, with or without positive margins * "Salvage Low Risk Group" are those patients who experience a PSA failure (defined as at least 1 detectable PSA level \> 0.2 ng/ml or at least 2 consecutive increases in PSA levels over baseline which are at least 1 month apart after radical prostatectomy) with the following feature: - Pathologic T2-3aN0 disease (with no clinical evidence of metastases) with Gleason Score ≤7, with or without positive margins * Neoadjuvant hormonal therapy prior to radical prostatectomy is allowed, and post-prostatectomy hormonal therapy prior to any protocol therapy is also allowed. * Prior chemotherapy, and/or radiation therapy is allowed if it has been at least 3 years or longer since those therapies were given from the time of registration, with the exception of previous pelvic radiation which is NOT allowed under any circumstances. * Karnofsky Performance Status ≥ 70. (Appendix A) * Hematologic parameters must be within the following limits: * WBC ≥ 3,000/uL * Platelet Count ≥ 100,000/uL * Hemoglobin level ≥ 10.0 g/dl * Patients with a history of an invasive malignancy within the last 3 years are not eligible for the protocol; patients who are NED from a prior invasive malignancy for at least 3 years or longer are eligible for the trial. Patients with history of benign tumors such as a pituitary macroadenomas, meningiomas, or craniopharyngiomas are eligible as long as the benign tumor is under local control regardless of the time frame. Patients with concurrent adequately treated basal cell or squamous cell carcinoma of the skin are also eligible for the protocol. * Patients must sign an Informed Consent Form. * Must not have concomitant medical, psychological or social circumstances which would interfere with compliance with the protocol treatment and follow-up. * Age ≥ 18 years. * Men of childbearing potential must be willing to consent to using effective contraception while on treatment and for a reasonable period thereafter, which should be for at least 6 months after the completion of protocol therapy. EXCLUSION CRITERIA Subjects meeting any of the exclusion criteria at baseline will be excluded from study participation. * Patients who have received prior pelvic irradiation are not eligible. * Any coexisting medical condition precluding full compliance with the study. * Patients with active infections or known infection with HIV. Testing for HIV status will not be required. * Psychological, familiar, sociological or geographical conditions which would not permit compliance with the study protocol.