RATIONALE: Androgens can stimulate the growth of prostate cancer cells. Hormone therapy using leuprolide and flutamide may fight prostate cancer by reducing the production of androgens. Combining radiation therapy with hormone therapy may kill more tumor cells. PURPOSE: Phase II trial to study the effectiveness of hormone therapy plus radiation therapy in treating patients with prostate cancer.

OBJECTIVES: * Assess the disease free survival of patients with localized adenocarcinoma of the prostate cancer. * Evaluate the toxic effects of three dimensional conformal external beam radiotherapy and androgen deprivation in these patients. OUTLINE: Patients are stratified according to PSA values and Gleason scores (class II versus class III/IV). Patients receive intramuscular leuprolide acetate every 3 months, and oral flutamide tid. Patients are evaluated on a monthly basis for response. Patients with unchanged or undetectable prostate specific antigen levels are considered to have reached maximal hormonal response and three dimensional conformal external beam radiotherapy is instituted. In addition, patients with disease progression are considered to have reached maximal response, and three dimensional conformal external beam radiotherapy is instituted. Radiotherapy must be administered within 6 months after initiation of leuprolide and flutamide therapy. Hormonal therapy is administered until 9 months of treatment have elapsed. Patients will be followed every 3 months for the first year, every 4 months for the second and third years, and every 6 months thereafter. PROJECTED ACCRUAL: A total of 105 patients will be accrued from biologic class II over 3 years, and 58 patients from biologic class III-IV.