In a health care environment strongly concerned with cost containment, cost-benefit studies of new technology must include analyses of loco-regional tumor control, morbidity, impact on quality of life, and financial considerations. This nonrandomized study analyzes 124 patients treated with three-dimensional conformal radiation therapy (3D CRT) and 153 with standard irradiation (SRT) between January 1992 and December 1995, for histologically proven adenocarcinoma of prostate, clinical Stage T1 or T2. Mean follow-up is 1.4 years. Three-dimensional CRT consisted of six or seven coplanar oblique and lateral and, in some patients, AP fields designed to treat the prostate with a 1 to 1.7 cm margin. SRT consisted of 120 degrees bilateral arc rotation. Total doses to prostate were 67 to 70 Gy when pelvic lymph nodes were irradiated or 68.4 to 73.8 Gy when prostatic volume only was treated; dose per fraction was 1.8 Gy. Patients were interviewed weekly for severity of 12 acute intestinal and urinary pelvic irradiation side effects (0 to 4+ grading). Time and effort for 3D RTP and daily treatment with 3D CRT and SRT were recorded. Dose-volume histograms (DVHs) were calculated for gross tumor volume, planning target volume, bladder, and rectum. Actual reimbursement to the hospital and university was determined for 41 3D CRT, 43 SRT, and 40 radical prostatectomy patients treated during the same period. Average treatment planning times (in minutes) were: 101 for 3D conformal therapy simulation, 66 for contouring of target volume and sensitive structures, 55 for virtual simulation, 39 for plan preparation and documentation, 65 for physical simulation, and 20 for approval of treatment plan. Daily mean treatment times were 19 min for 3D CRT with Cerrobend blocking, 16 with multileaf collimation, and 10 with bilateral arc rotation. Dosimetric analysis (DVHs) showed a reduction of 50% in volume of bladder or rectum receiving doses higher than 65 Gy. Acute side effects included dysuria, moderate difficulty in urinating, and nocturia in 25-39% of both SRT and CRT patients; loose stools or diarrhea in 5-12% of 3D CRT and 16-22% of SRT patients; moderate proctitis in 3% of 3D CRT and 12% of SRT patients (p = 0.01). Chemical disease-free survival (prostate-specific antigen < or =2 ng/ml) at 3 years was 90% with 3D CRT and 80% with SRT (p = 0.01). Average initial treatment reimbursements were $13,823 (3D CRT), $10,864 (SRT), and $12,250 (radical prostatectomy). Average total treatment reimbursement and projected cost of management of initial therapy failures per patients were $15,173, $16,264, and $16,405, respectively. Three-dimensional CRT irradiated less bladder and rectum volume than SRT; CRT initial reimbursement was 28% higher than SRT and 12% higher than radical prostatectomy. Because of projected better local tumor control, average total cost of treating a patient with 3D CRT or radical prostatectomy is equivalent to cost of SRT. Treatment morbidity was lower with 3D CRT. Our findings reflect an overall benefit with 3D CRT as a new promising technology in treatment of localized prostate cancer. Dose-escalation studies may enhance its efficacy and cost benefit.