The experience with neutron irradiation in locally advanced adenocarcinoma of the prostate

Patients with locally advanced adenocarcinoma of the prostate, defined as those with extraprostatic disease, a Gleason score of 7 or higher, or a PSA of 15 ng/mL or higher, have a significantly worse prognosis with standard external beam radiotherapy. Post-treatment PSA and biopsy data confirm that most patients have residual local disease as a component of failure in most cases. Two randomized trials of neutron irradiation mixed with photon irradiation and neutron irradiation alone compared with standard photon irradiation to a dose of 70 cGy have both confirmed an improvement in the disease-free survival of patients treated with neutron irradiation. The high complication rate in the second study and the limited number of neutron facilities led to a dramatic decline in the utilization of neutrons in prostate cancer. However, at Wayne State University, using a super conducting cyclotron, a number of clinical studies have been performed to demonstrate the safety and efficacy of neutron irradiation. Chronic complication rates have been low. Biochemical freedom from relapse rates have been excellent. For patients with a pretreatment PSA <10 ng/mL, 10 to 20 ng/mL or >20 ng/mL, 92%, 85%, and 38% of patients have no evidence of disease at 4 years. Thus, neutron irradiation has been proven to be a safe method of dose intensification that can lead to a significant improvement in the overall outcome of patients with nonmetastatic adenocarcinomas of the prostate.