BOSTON (EGMN) - Cancer patients who received proton beam irradiation had a lower risk of developing secondary malignancies than did patients who underwent standard photon-based irradiation in a retrospective study.Among 503 patients who underwent proton-beam therapy from 1974 to 2001, 6.4% developed secondary malignancies, compared with 13.1% of 503 matched controls treated with photon irradiation, investigators reported at the annual meeting of the American Society for Therapeutic Radiology and...