Proton therapy can treat all solid-tumor cancers, including breast, colorectal, lung, brain, head and neck and prostate cancer. It benefits patients whose tumors are solid with defined borders, meaning the cancer has not spread to other parts of the body. Proton therapy is often the only choice when treating tumors that were previously irradiated (i.e., treated with conventional radiation). Proton therapy is sometimes used in combination with surgery and/or chemotherapy. It may be used instead of surgery in some cases, making it ideal for inoperable tumors. If you have a cancer where it is likely to be effective, we will evaluate your diagnosis to find the best option.