One thing we heard from both the Oncologist and from the Surgeon when my Wife was going though her bout with cancer was be very careful what you read or take from the internet...there are several locations (American cancer society, Mayo Clinic, etc) that will carefully give some information but every case of cancer is very different and one on one diagnosis will give the best result.
One more thing...with breast cancer the "food for the cancer" is estrogen..not sugar or other things...when estrogen is removed from the picture the cancer loses it's ability to feed...that is the main target of breast cancer after a lump removal or mastectomy...so a blanket statement about sugar, etc may have no bearing on the type of cancer involved..
We almost drove each other and the doctors nuts by looking at the internet babble and listening to self professed experts that were neither doctors nor directly involved as a cancer patient.
An aside...I have a close friend that has glaucoma and is losing his eyesight..his pressures are way up and it's going to cost him his eyesight....he is a "homeopathic guru" and has ignored the doctor's advice to use eye drops to relieve the pressures on the optic nerve...he's taking massive doses of green and blue algae as a home remedy...his eye sight is getting worse and the doctor has shown him the proof positive of what is occurring but he's locked in to the algae treatment that some "expert" on the internet has professed is the best treatment.
Not my eyesight and not my family but it's not working and the outlook is not good..lots of that same kind of thing in all diseases...