Proton Beam Therapy and Sexual Side-effects ?

[Guest guest]

I'm looking into proton beam therapy for a friend. The " Ten-Year Study " that's

referenced on the " Proton Bob " website talks about urinary side-effects of

proton beam therapy, but not sexual side-effects.

The Loma website makes this claim:

.. . . " This means a much lower chance of side effects

.. . . such as incontinence or impotence in prostate cancer patients. "

Can anyone point me to _data_ that supports that claim (as regards impotence) ?

Thanks --

PS -- I'm looking for something statistical, not something anecdotal. I'll be

checking YANA next . . .