81-year old mom considering treatment

T1c means that the tumor was between 1 and 2 cm - fairly small. N0 and M0 mean that there were no postive nodes or mets. Stage I is the lowest stage. Nottingham scores run from 1 to 9 and are a measure of how different the cancer cells were from regular cells under a microscope. 1 is the lowest score. They get grade from the Nottingham score with scores 1 - 3 being grade 1. It means her cancer probably wasn't very aggressive.

A partial mastectomy I think means a lumpectomy where they took out the cancer and left part of the breast. Recurrence with a lumpectomy without radiation is fairly high - about 40% for 5 year recurrence but I haven't seen data on whether grade affects this. Radiation brings this to about 10%, about the same as having a full mastectomy without radiation. 

Since radiation therapy is pretty short term and usually has little in the way of side effects, it might be reasonable to do that and skip the aromatase given her age and tumor characteristics. If the cancer was on her left side, there is a small risk of heart damage from the radiation so they would probably need to be very careful to keep the radiation away from her heart. A radiation oncologist should be consulted in addtion to her medical oncologist for helping to decide whether that risk is reasonable in her case.