Background: Laboratory research and initial clinical trials conducted in Japan raises the possibility that a simple and inexpensive treatment based on a very dilute (0.5%) hydrogen peroxide injected into cancers under local anaesthetic greatly increases the effectiveness of standard doses of radiotherapy. The side effects appear to be limited to mild/moderate discomfort at the injection site for up to 24 hours in one-third of patients. Rapid, complete and durable tumour disappearance has been reported in 49/55 bulky breast cancers in Japanese women treated using this approach, a response that is at least 3 times the success rate of radiotherapy alone in our own patients and in a contemporary Japanese control population. The inventor, Prof Ogawa of Kochi University, has approached the investigators to lead the further clinical evaluation and commercial development, starting with the proposed early phase trials testing safety and anti-cancer activity described below.