Prostate cancer treatment an individualized process

DEAR DR. ROACH: I read your recent column on prostate cancer treatments, and I must disagree on the differences between IMRT 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 consider any treatment other than proton radiation therapy for prostate cancer to be archaic medicine and not to be used. — M.D.

ANSWER: I 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 percent is much less than the eight percent 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 GI toxicity among proton-beam treated patients, I reaffirm my recommendation that there is not yet a compelling reason to choose proton treatment over IMRT.

If you have proof your urologist was benefitting financially from sending you to IMRT, you should report it. Several readers told me they felt their physician sent them for one treatment or another based on financial incentives (including high-intensity focused ultrasound, which is not standard therapy in the U.S. despite favourable data in Europe).

Choosing between surgical and radiation treatment for prostate cancer is not simple. The decision for any man depends on his medical condition, the size and aggressiveness of the cancer, and personal preferences.