Less toxicity and higher cure rates than achievable with X-ray therapy

Benefits of Proton Therapy In most cancers requiring radiation therapy, proton therapy can produce better radiation dose distributions with respect to cancer and normal tissue than techniques employing X-rays. A better radiation dose distribution is more important in some clinical situations than others. When considering possible benefits of proton therapy, it is useful to consider the therapeutic ratio likely with other radiation therapy treatment options first—i.e., the probability that other radiation options will control the tumor without causing toxicity. In some cancers, proton therapy is the only treatment option, offering hope for cure without unacceptable toxicity. Examples in this category include chordomas and chondrosarcomas occurring at the base of the skull. Because of proximity to critical structures such as the brainstem and optic nerves, surgery alone is rarely successful and sufficient radiation doses to destroy these tumors usually cannot be given with X-ray therapy. However, clinical researchers at Harvard have reported excellent long-term disease control with minimal toxicity with proton therapy.1-3 In a second group of cancers, other treatment options are available, but the therapeutic ratio of these other options leaves room for improvement in either tumor control or normal tissue toxicity. In these cases, clinical or dosimetric data suggest an important and likely measurable benefit of proton therapy. One example is melanomas of the eye, which can be treated with surgical removal of the entire eye, radiation with a cobalt plaque, or proton therapy. Large clinical trials from the U.S. and England show similar survival rates among the three treatment options, but better long-term preservation of vision with proton therapy.4 A second example is pediatric tumors, in which even low radiation doses to normal tissues cause measurable effects on neurocognitive function, muscle and bone growth, endocrine function, etc., so any savings in normal tissue exposure from proton therapy is likely to produce measurable benefits. A third example in this category is early stage prostate cancer where there is room for measurable improvement in disease control, but not at the price of additional toxicity.5 The improved dose distribution achieved with proton therapy was used to the Promise of Proton therapy is two-fold— Less toxicity and higher cure rates than achievable with X-ray therapy