Patients with localized prostate cancer and treated with carbon ion radiotherapy may have a lower risk of subsequent primary cancers than those treated with photon radiotherapy, a new study suggests. Eligible patients in the retrospective cohort study had histologically confirmed localized prostate cancer and a minimum follow-up of at least 3 months. Researchers found:

• Of 1,580 patients who received carbon radiotherapy for prostate cancer, 1,455 (92%) patients met eligibility criteria.
• Of 38,584 patients identified with prostate cancer, 1,983 (5%) patients treated with photon radiotherapy and 5,948 (15%) treated with surgery were included.
• 234 subsequent primary cancers were diagnosed in the carbon ion radiotherapy cohort.
• In propensity score-weighted analyses, carbon ion radiotherapy was associated with a lower risk of subsequent primary cancers vs photon radiotherapy (HR 0.81) or surgery (HR 0.80), whereas photon radiotherapy was associated with a higher risk of subsequent primary cancers vs surgery (HR 1.18).