She will probably be seeing an oncologist, a medical oncologist, and who is not involved with sugery but the medical (drug) treatment for her cancer, if indicated, and which it sounds it is in yoiur mother in law's case.
No matter if it is true that her lesion will start smelling, or not, she needs to be treated, and surgery may not be the best treatment for her and at this time, or ever. The doctor she has an appointment with may decide to start her on chemotherapy; he may also order a bunch of scans to find out if her cancer has spread to other parts of her body.
If, and when she has surgery, she may be able to avoid general anesthesia as breast surgery is not that painful compared to many other surgeries.
Her treatment may not be clear at this point and we often do not know how things develop, or how we respond to one procedure/medicine, or another. Treatment is often a process. we cannot tell you the answers but you will know more after talking to the doctor, or after your mother in law has more information and tests. It really helps when a new cancer patient has someone to be with her/him as it is very difficult to understand in the first place what you were told, never mind what you remember. A second pair of ears is a wonderful thing to have with you, both for information and also for support.
Best, KATRIN
She is 86 years old and has had the lump for a little over a year, but didn't tell anyone. It started bothering her about a month ago, so she had the doctor, a doctor, look at it. A biopsy was done and came back as maligant. She has several doctors and I am not sure which doctor dignosed her, but her kidney doctor told her not to have the lump removed because she could die on the operating table. She has issues with her kidneys, high blood pressure, heart problems, etc. Then last week another doctor told her that she needed to have it removed because it was going to start smelling. She does not have any type of discharge and that is why I am puzzled at the comment that it will start smelling. She has an appointment with the doctor that told her not to get it removed on Friday. I am sure as to what exactly the doctor told her, but that is what she told us.
Are you sure she has breast cancer? Did she specifically tell you that? Or the doctor her?
Because a smelly lump could also be caused by infection, either bacterial or fungal.
You do not give any history?
Best,
KATRIN