Anecdotally, I have worked with a mother, via email, many years ago now.
SHe had bilaterally Wilms tumor, I guess, and received radiation therapy for
these.  She survived, but had much difficulty bf.  I have a neighbor who is
a radiation oncologist,..he explained to me that while radiation from an
xray {regular xray, diagnostic for broken leg..dental work, etc.} was like a
water droplet, radiation to treat cancer was like Niagara Falls....The first
will not impact bf ability, but the latter may indeed have impact.

This is anecdotal only. Please check Ruth Lawrence, or maybe you will find
out more here.

Kathleen
Kathleen B. Bruce, BSN, IBCLC co-owner Lactnet,Corgi-L,TLC, Indep. Consultant
http://together.net/~kbruce/kbbhome.html
LACTNET Archives http://library.ummed.edu/lsv/archives/lactnet.html
It is possible for your mind to be so open that your brain falls out.