Prospective Evaluation of Pencil Beam Scanning Proton Therapy for Previously Irradiated Tumors

The goal of this clinical research trial is to study the use of differing investigational doses and scheduling for Proton Therapy for tumors previously treated with radiation therapy. Generally, when patients are first treated for cancer with radiation therapy, they are treated with traditional photon (or x-ray) radiation therapy, which uses high-energy waves to kill tumor cells. In some cases, the cancer either returns or a new tumor can present in a different part of the body. With the usual radiation treatment, the photon beams travel all the way through the body. As a result, healthy tissues in front of and behind the tumor are exposed to radiation. Physicians who treat these cases where the tumor has returned often use a much lower dose of radiation to prevent patients from experiencing serious and long-term side-effects. This dose is often not strong enough to destroy the cancerous tumor. Alternatively, they may also treat a smaller area than would be indicated for complete tumor eradication, again in an attempt to prevent serious and long-term toxicities, but at the cost of optimally treating the cancer. Proton therapy, however, may offer a chance to safely deliver a more effective dose and volume of radiation as it is more targeted and can spare healthy tissues surrounding the tumor. The reason we are conducting this research study is to look at whether Proton therapy can be a better way to treat reoccurring tumors in patients who have previously received radiation therapy to the same area, compared to treatment approaches used to date.