The aim of this study is to investigate whether proton beam radiotherapy in locally advanced rectal cancer can offer meaningful reductions in acute gastrointestinal toxicity compared to standard treatment with photons which may improve patient's tolerability of neoadjuvant chemotherapy.~There are currently no published clinical reports evaluating the use of proton therapy in the upfront treatment of locally advanced rectal cancer. There are further no published randomized trials comparing radiotherapy with photon vs proton in locally advanced rectal cancer.~This is a prospective randomized trial, initially run at the limited number of centres but later expanded to other centres participating in the Skandion network. Patients will be treated with short course 5 x 5 Gy radiation scheme with either photons (standard arm) or protons (Skandion clinic) followed by four to six cycles of combination chemotherapy (capecitabine and oxaliplatin) and surgery. The rectal tumour will be removed by TME/PME surgery or more extensive surgery if required because of tumour extent.~All patients will receive at least 4 courses of CAPOX (Capecitabine b.i.d.1000 mg/m2 day 1-14 every 3 weeks, Oxaliplatin 130 mg/m2 day 1 every 3 weeks) week 3-14, followed by surgery at week 17-20.
To investigate a potential toxicity benefit of preoperative radiation therapy with protons compared to conventional photon beam radiation therapy in patients with locally advanced rectal cancer.