Complete remission of perineal extra-mammary Paget's disease by curative-intent radiotherapy using volumetric modulated arc therapy in a patient older than 90 years.

Localized extra-mammary Paget's disease (EMPD) is mainly treated with surgical resection. Curative radiation therapy (CRT) is an alternative to surgery. Electron beams and conventional X-ray methods have been used in patients with EMPD for radiotherapy. The present report describes the case of a very elderly patient with perineal EMPD who was treated with definitive radiotherapy consisting of 60 Gy in 30 fractions. Surgery was deemed too difficult because of his age and comorbidities. We adopted volumetric modulated arc therapy as the radiotherapy modality, a recent, advanced form of intensity-modulated radiation therapy. Grade 3 dermatitis was observed as an acute phase adverse event, and he achieved a complete response and maintained remission for over one-year post-treatment. Our radiotherapy treatment protocol resulted in good clinical outcomes; therefore, it may be a candidate for inoperable patients with EMPD.