I have been lurking for about a week now.  Had to respond with a case study.
 Patient had a tumor removed from left breast several years ago; pregnant
with first child.  Saw LC for prenatal visit.  LC wasn't sure that patient
would be able to exclusively breastfeed but encouraged trying.  At last
visit, baby girl, Katie, was still exclusively breastfeeding at five months.
 Mom reports less milk from left breast and Katie prefers/nurses better on
right.  So, to anyone who questions, we use this mom and baby as an example.
 Exclusive breastfeeding may not be possible in all cases.  Prenatal visit
and education of mom seem to be key.
FYI--I am breastfeeding coordinator for state WIC program here in Arkansas
and administrator for Office of Breastfeeding Services. We do variety of
things, including clinic 2 days per week and supply all state WIC office with
breastfeeding materials.  .