The following is from today's JHU Health Bulletin.
Jim
Proton Beam Therapy:
Does Newer and Costlier Mean Better?
Men diagnosed with prostate cancer are faced with an array of treatment options. Proton beam therapy -- a form of external beam radiation therapy -- is one choice that's growing in popularity. But proton beam therapy is a controversial option, with some critics suggesting that its popularity may be driven by advertising rather than sound scientific evidence of benefit over other therapies.
Proton beam therapy is a variation on conventional, or conformal, radiation therapy for prostate cancer treatment. Conventional radiation therapy uses x-rays (also called photons) to destroy tumors. Proton beam therapy uses protons to irradiate, or kill, cancer cells. Protons (positively charged atoms) have certain unique qualities that set them apart from x-rays and allow doctors to target proton beams with greater precision.
In theory, this pinpoint-targeting ability should make proton beam therapy less likely than conventional radiation treatments to damage healthy tissue in the vicinity of a tumor.
But here's the rub: Few prostate cancer patients receive conventional radiation treatments these days. Over the last decade, a more refined version of conventional radiation known as intensity-modulated radiation therapy (IMRT) has become by far the most common method for using x-rays to eradicate prostate tumors.
IMRT uses computers to produce three-dimensional images of tumors. Doctors then use these images to irradiate a tumor from many different angles. Like proton beam therapy, IMRT was designed to limit damage to healthy neighboring tissues.
Studies have shown that when it comes to eliminating tumors and treating prostate cancer, proton beam therapy works about as well as IMRT. However, relatively little research comparing the safety profiles of proton beam therapy and IMRT has been conducted.
One recent study, reported in the Journal of the American Medical Association (JAMA), is helping to provide much needed clarity. Overall, the investigators reported that there was no significant difference between proton beam therapy and IMRT -- with one major exception. Men treated with IMRT were 34 percent less likely than those who had proton beam therapy to develop gastrointestinal problems after their treatments.
IMRT vs. proton beam therapy: the cost factor. Proton beam therapy is significantly more expensive to perform than IMRT. One study found that treating a prostate cancer patient in his 60s or 70s with proton beam therapy costs about $64,000 on average, compared with $39,000 for IMRT.
But the JAMA findings raise an important question: All else being equal, if proton beam therapy is more likely than IMRT to produce adverse gastrointestinal effects, why pay the additional cost?
Patients aren't the only ones with a vested interest. Insurers (including Medicare) and hospital administrators have a stake as well. Setting up a proton beam clinic requires a major investment of space and money -- as much as $180 million. While proton beam therapy has a role in treating many different forms of cancer, many hospitals assume that a good number of the patients to be treated will be men with prostate cancer. If that assumption is wrong, will they be able to recoup their costs? And if proton beam therapy offers no advantage over a less expensive prostate cancer therapy, why should insurers pay for it?