Both traditional and alternative medicine would recommend removal of the tumor.
As zouzi stated, this is a decision that can only be made in collaboration with your grandmother's doctor(s).
However, it may give you some reassurance to read the following article about another woman, now 81, who was diagnosed with BC and had surgery at age 80:
http://blog.al.com/breaking/2010/10/huntsville_1.html
Best wishes to both you and your grandmother...
Hi,
I am so sorry that your grandmother has been diagnosed with breast cancer.
I am afraid that the answer to your question can only be given by her treating doctors who know all the details in her particular case.
Considering her age and her health status, I am positive that her team of doctors have taken all the necessary steps and precautions to make sure that your grand mother will have a successful surgery and will be treated the best way possible.
Wishing you all the best to you and your grandmother.