U.S. researchers suggest proton therapy -- a type of external beam radiation -- is effective for localized prostate cancer with minimal side effects. In one study, researchers at the University of Florida in Jacksonville studied 211 men with low-, intermediate- and high-risk prostate cancer. The men were treated with proton therapy, a specialized type of external beam radiation that uses protons instead of X-rays. Nancy Mendenhall of the university\'s Proton Therapy Institute said the treatment was effective and the gastrointestinal and genitourinary -- reproductive organs and the urinary system -- side effects were generally minimal. In a second study, researchers at Massachusetts General Hospital in Boston, Loma Linda University Medical Center in Loma Linda, Calif., and the Radiation Therapy Oncology Group in Philadelphia performed a case-matched analysis comparing high-dose external beam radiation therapy using a combination of photons (X-rays) and protons with brachytherapy (radioactive seed implants). Over three years, 196 patients received the external beam treatments. Their data was compared to 203 men of similar stages who received brachytherapy over the same time period. \"For men with prostate cancer, brachytherapy and external beam radiation therapy using photons and protons are both highly effective treatments with similar relapse rates,\" said Dr. John J. Coen, a radiation oncologist at Massachusetts General Hospital in Boston. \"Based on this data, it is our belief that men with prostate cancer can reasonably choose either treatment for localized prostate cancer based on their own concerns about quality of life without fearing they are compromising their chance for a cure.\" The findings were published in the International Journal of Radiation Oncology•Biology•Physics.