A warning to men considering a pricey new treatment for prostate cancer called proton therapy: Research suggests it might have more side effects than traditional radiation does.
A study of Medicare records found that men treated with proton beams later had one-third more bowel problems, such as bleeding and blockages, than similar men given conventional radiation.
This is an observational study so it is not definitive, but it is one of the largest to compare these treatments. Proton therapy is rapidly growing in use — Medicare covers it — even though no rigorous studies have tested whether it is as safe or effective as usual care.
It costs around $48,000 — at least twice as much as other prostate radiation treatments. Hospitals are rushing to build proton centers, and nine are operating now — sites include the University of Florida Proton Therapy Institute in Jacksonville. Promoters often claim it is less likely to cause complications.
Proton therapy uses proton particles instead of X-rays. In theory, it targets radiation more directly to tumors and spares healthy tissue, which should lead to fewer side effects. Its value is established for treating eye and certain pediatric tumors. But it often is marketed for prostate cancer.
Researchers checked Medicare records on more than 12,000 men treated for early-stage prostate cancers from 2002 through 2007. First they compared an older version of external beam radiation to a newer form that now dominates the field — intensity-modulated radiation therapy, or IMRT. It, too, targets radiation more precisely to the prostate, and this is the first large study to show it was better than the older method — even though it came into use a decade ago.
The study also compared 684 men with proton therapy to a group treated with IMRT. There were 18 cases of bowel problems for every 100 proton therapy patients per each year of follow-up versus 12 such problems for those treated with IMRT.
The federal Agency for Healthcare Research and Quality paid for the study, which included researchers from the National Cancer Institute. The government also is funding a definitive study to compare proton therapy to other types.