Radiation oncologist Dr. Peter Rossi, who specializes in the treatment of prostate cancer, has written about some of the benefits of radiotherapy. These benefits include the death of a deep volume of cancer cells, eradication of microscopic disease at the tumor perimeter, the ability to reduce the size of tumors, cooperative interaction with systemic therapy, preservation of one's own organs, stimulation of an immune response against the tumor and a relatively safe and painless treatment for the patient