Superiority of proton beam unproven

Dear Dr. Roach: I recently have been diagnosed with early prostate cancer. My Gleason score is 7. My urologist has informed me that he doesn’t think I am a good candidate for surgery, due to having atrial fibrillation. My radiation oncologist has recommended traditional radiation therapy. However, I am worried about the possible side effects. I am 72.

I am considering proton therapy and wonder if you have any thoughts.

R.O.B.

Answer: You have intermediate-risk prostate cancer, based on your Gleason score. Most experts would recommend radiation or surgery. Atrial fibrillation itself is not necessarily a reason NOT to get surgery; however, the side effects probably are less with radiation compared with surgery.

Radiation may be delivered from the outside, either with X-rays or protons, or from the inside via internal radiation “seeds” implanted surgically, called brachytherapy. Side effects of radiation include urinary complaints and rectal bleeding, pain and urgency. Sexual function also may be affected; however, modern X-ray radiation techniques (called intensity-modulated radiation therapy) are much better at avoiding the structures that can lead to these complications.

The research data has shown that there is not a survival difference comparing radiation and surgery. When comparing IMRT and proton beam treatment, there is no convincing evidence that proton beam therapy is more effective, but there is weak-to-moderate evidence of MORE side effects with proton beam, especially more GI symptoms (34 percent higher in the proton beam group). A head-to-head trial would be needed for definitive data. Proton beam is much more expensive. Brachytherapy, on the other hand, seems to have similar side effects and at least as good outcomes.

All three options (Xray, proton beam and brachytherapy) are reasonable, have similar effectiveness and relatively low side effect rates in the bladder and bowel, and higher in sexual function. However, I don’t see a reason to prefer proton treatment at the present time over IMRT.

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