Dear Dr. Roach: I read your recent column on prostate cancer treatments, and I must disagree on the differences between intensity-modulated radiation therapy and proton radiation therapy. IMRT or X-rays can cause secondary aggressive cancers of the bowels or bladder. I know of an individual who died from this type of cancer after IMRT. Proton radiation therapy does not cause secondary cancers because of the way protons work.
Secondary cancers due to IMRT occur in about eight per cent of patients. This may be acceptable odds for radiation oncologists, but not to patients who develop them. Also, many doctors own the IMRT machinery and will send patients there for financial reward, which is what happened with my former urologist. When I found this out, I terminated my relationship with him.
I hope this explains why I consider any treatment other than proton radiation therapy for prostate cancer to be archaic medicine and not to be used.
M.D.
I always appreciate hearing differing opinions from my own, and here is why I disagree.
The lifetime risk of a second malignancy after IMRT (now considered standard radiation treatment) for prostate cancer has been estimated to be about one person in 220 in all patients, but as high as one person in 70 (about 1.5 per cent) among those who are followed over 10 years — 1.5 per cent is much less than the eight per cent you quote.
Proton therapy should have a decreased risk of secondary malignancy, but that is unproven. While early reports suggest that the risk of secondary malignancy in proton therapy may be about half the risk seen in traditional IMRT, proton therapy clearly does have an increased risk of secondary malignancy. Given a lack of proof of improved efficacy of proton therapy in survival in prostate cancer, and increased gastrointestinal toxicity among proton-beam-treated patients, I reaffirm my recommendation that there is not yet a compelling reason to choose proton treatment over IMRT. That may change as further data accrue and as we learn how best to use proton treatments, which in theory could have less risk to surrounding tissues.
In the U.S., if you have proof that your urologist was benefiting financially from sending you to IMRT, you should report it to Medicare or Medicaid, as appropriate. That is a violation of the Stark Law and/or anti-kickback statutes, and it is both illegal and unethical for a physician to do. Interestingly, I had several readers tell me that they felt their physician sent them for one treatment or another based on financial incentives (including IMRT, proton therapy and high intensity focused ultrasound, which is not yet considered a standard therapy for prostate cancer in the U.S. despite favourable data in Europe). Physicians know they are not allowed to refer to an entity that they or a family member has a financial stake in.
I also must point out that choosing between surgical treatment for prostate cancer and radiation treatment is not simple, and the right decision for any individual man depends on his medical condition, the size and aggressiveness of the cancer, and his personal preferences. I hope that the information in this column can enhance the discussion between a man with his doctor about the right treatment for them.
Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to [email protected].
