Rectal cancer eradication by proton beam therapy complicated by radiation proctitis: a case report

A 74-year-old woman presented to her local physician with hematochezia. Colonoscopy showed a locally advanced 30 mm cancer adjacent to the anus. She refused abdominoperineal resection because of the necessity for a permanent stoma and decided to receive proton beam therapy (70.4 Gy equivalent) as an alternative treatment in another hospital. After proton beam therapy, the rectal cancer was eradicated at colonoscopy, and she was referred for surveillance. One year later, she developed frequent hematochezia. Colonoscopy revealed dilated vessels with oozing hemorrhage in the tumor scar. This was diagnosed as hemorrhagic radiation proctitis induced by proton beam therapy. Over 8 months, endoscopic hemostatic therapy was performed five times using argon plasma coagulation for refractory hemorrhagic disease. The patient's hemoglobin level dropped to as low as 4.5 g/dl requiring blood transfusion. Thereafter, the radiation proctitis gradually improved and there is no evidence of recurrent tumor for over 10 years. To the best of our knowledge, there are no previous reports of proton beam therapy eradication of locally advanced rectal cancer. Clinicians should be aware that radiation-induced proctitis with refractory hemorrhage could develop.