In the case of a high upper outer quadrant early stage breast cancer without adverse histological factors, would you omit boosting the breast lumpectomy cavity if the treatment area would involve a significant portion of axilla due to risk of lymphedema?   

There is a great thread on when to boost from TheMedNet- so that's a good place to start - to figure out if they need a boost or not. It shouldn't be just histologic factors - age is also important. To paraphrase, what they said - if you'd consider skipping RT altogether, then those patients do...

Agree with @Simul Parikh. I do not consider the location of the cavity as a factor of boosting or not. The priority is to reduce local recurrence with radiation so the breast including the cavity should be well covered. In that case, I am not aware of hard evidence suggesting significantly increased...