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All too often, the most brutal part of a bout with cancer is radiation therapy. X rays are electromagnetic waves that travel with a constant amount of energy, so although they effectively kill cancer cells, they pass through the skin and healthy tissues on their way to and from the tumor. In doing so, they damage the normal cells in their path. Protons, on the other hand, are particles that have a mass and a charge (they are positive). They can thus be targeted with exquisite specificity only to the tumor site, emitting the bulk of their radiation there and there only and sparing patients the terrible side effects that can accompany therapy with X rays.
For subatomic particles, protons are quite large. They therefore do not scatter to the sides, as X rays do, but stay in a straight beam. During proton therapy, a particle accelerator — much like the Large Hadron Collider in Switzerland currently being used by physicists to explore the nature of the cosmos — is used to endow the protons with a given amount of energy which determines how far into the body the proton beam penetrates. Tumors close to the skin are targeted with lower energy proton beams, while those buried deeper require higher energy beams. The dose of radiation delivered to tissues peaks in a burst just at the end of the protons’ range, which the physicians plan to be at the back of the tumor. So in contrast to X rays, proton radiation does not leave the body and damage tissues on their way out, behind the tumor.
This ability to target the radiation precisely to the tumor by controlling the protons’ energy is the key to allowing physicians to maximize the therapeutic doses of radiation targeting the tumor while curbing the radiation exposure to healthy cells and thus severely limiting the side effects suffered by patients. Treatment is painless, and most patients are able to maintain their work and exercise routines while undergoing it. They are not at any risk of exposing others around them to radiation.
The idea of using protons to target tumors emerged in the late 1940’s, after particle accelerators were built as part of the nuclear research going on in WWII. According to Brian Chon, M.D., a radiation oncologist with Princeton Radiation Oncology in Princeton, New Jersey, and the Medical Director of the brand new ProCure Proton Therapy Center in Somerset, New Jersey, proton therapy is only now becoming more mainstream because:
…building a proton therapy center is a very complex and difficult thing to do. In the last five to ten years, there has been a convergence of technological innovations — notably image guidance systems and the complex computer software required to manage them — that can finally allow us to take advantage of proton therapy. ProCure and other companies have streamlined the process of financing and building these centers.
Proton therapy is best suited to those cancers that are buried deep within the body and therefore difficult to reach by other means, as well as those requiring doses of radiation that are too high to be tolerated by the rest of the body. Its primary benefit is improved quality of life, and its reduced damage to healthy tissues is a particular boon in pediatric cancers.
To date there are only ten proton therapy centers in the country, but “every premiere cancer center in the world either has a proton therapy center or is getting one,” said Dr. Chon.
M.D. Anderson already has a proton therapy center in Texas, and the Mayo Clinic is currently building facilities in both Minnesota and Arizona. ProCure Treatment Centers, Inc — a privately held healthcare company dedicated to improving the lives of patients with cancer by increasing access to proton therapy — just opened their third proton therapy center in the U.S., this one in Somerset, New Jersey . “We are excited to be the first and only proton therapy center in the state of New Jersey and the entire New York metropolitan area,” said Dr. Chon.
The debate over proton therapy
Although proton therapy appears to offer a number of benefits, there are critics of the treatment. In 2009, a systematic review evaluated 243 published articles on proton therapy. Of the 243, only eight randomized and nine nonrandomized clinical trials compared treatment with or without charged particles . The review found no statistically significant or important differences in overall or cancer-specific survival or in total serious adverse events from any of the studies, suggesting that it’s not any safer or more effective than other cancer treatments.
Moreover, a recent Bloomberg article reported that although proton therapy can cost twice as much as traditional radiation therapy, it’s usually covered by Medicare or private insurance . According to Sean Tunis, chief executive officer of the Center for Medical Technology Policy, and a former Medicare official, hospitals are racing to build proton centers because the are “extremely favorably reimbursed” by Medicare and many private payers .
Amitabh Chandra, a health economist at Harvard University’s John F. Kennedy School of Government, said :
Proton-beam therapy is like the death star of American medical technology; nothing so big and complicated has ever been confronted by the system. It’s a metaphor for all the problems we have in American medicine.
The debate is far from over. More studies on the efficacy and rate of side effects (compared to conventional treatment) of proton therapy are coming. When it comes to costs in healthcare — a topic discussed frequently here at Highlight HEALTH — it’s not a matter of saving money but controlling costs and maximizing effectiveness, neither of which is an easy task in medicine today.
- ProCure, CentraState Healthcare System and Princeton Radiation Oncology Celebrate Grand Opening of New Jersey and Metro New York’s First Proton Therapy Center. ProCure. 2012 Mar 20.
Terasawa et al. Systematic review: charged-particle radiation therapy for cancer. Ann Intern Med. 2009 Oct 20;151(8):556-65. Epub 2009 Sep 14.
- Prostate Cancer Therapy Too Good to Be True Explodes Health Cost. Bloomberg. 2012 Mar 26.