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Higher Cure Rates and Fewer Side Effects Than Traditional X-ray Photon Radiotherapy
Proton therapy has been hailed as a revolutionary cancer treatment, with higher cure rates and fewer side effects than traditional X-ray photon radiotherapy. Proton therapy is the modality of choice for treating certain small tumors of the eye, head, head or neck. It is also safer -- especially for young children -- because it exposes less of the tissue surrounding a tumor to the dosage, proton therapy lowers the risk of secondary cancers later in life.

• Dr. Eric Klein of Washington University in St. Louis will begin the symposium with a session that presents the state-of-the-art in understanding and creating therapeutic beam of protons. In theory, a thin beam of protons can destroy a tumor with less damage to surrounding tissues than the broader cone of X-ray photons. This is because the protons penetrate a specific distance into the body and release most of their energy at the very end of this track and the effect is due to reverse Braggs peak.
• The largest session, chaired by Dr. Christopher Rose of the Valley Radiotherapy Associates Medical Group in California, will take a look the latest clinical studies that test these theoretical advantages in the treatment of cancers of the lungs, skull, and prostate. The technology has proven particularly promising for treating small, shallow cancers near the eyes and spine, and for tumors in children, whose developing organs could be damaged by collateral damage.
• Speakers in a sister session will argue for a lack of clinical evidence supporting some uses of proton therapy. Evidence that it is superior to older technologies is murky for prostate cancer, for example, a controversy that nevertheless has failed to deter the large number of people currently being treated for prostate cancer.
• "On paper, proton therapy undoubtedly has theoretical advantages … but there are many uncertainties involved when we deliver the radiation to the patient," says Dr. Jatinder Palta of University of Florida Health Science Center in Gainesville, who will chair a session considering these difficulties. While better imaging technologies have improved the aiming of proton beams, irregularities in body or the movements of internal organs can still throw off this targeting, causing unintended damage. The consequences of this damage and new schemes to avoid it will be considered.
• The process of creating proton beams also generates a large number of neutrons -- which may cause secondary cancers. Studies of survivors of the Hiroshima bomb, who received large doses of neutrons, will be presented to assess this risk.
• Members of the public health community will join in an evidence-based cost-benefit analysis of the treatment, which can costs two to three times more than traditional therapies. Five clinics with cyclotrons in the United States currently offer the treatment, with four more under construction and a tenth in development. When is the cost justified? What are the ethical issues involved? How can the planning of proton treatments be improved? These and other questions will be addressed both for the benefit of those in the field and for members of the press and public.

About AAPM
The AAPM is a scientific, educational, and professional nonprofit organization whose mission is to advance the application physics to the diagnosis and treatment of human disease. The Association encourages innovative research and development, helps disseminate scientific and technical information, fosters the education and professional development of medical physicists, and promotes the highest quality medical services for patients.

Source: AAPM