The doctor diagnosed my mother had breast cancer, as she had suspected, and prescribed some medications for her.
Your mother most likely detected a lump in one or both of her breasts. This is normally a sign for your mother to have a mammogram and to make a doctor's appointment for a follow-up to the mammogram. If somthing abnormal has been detected on the mammogram, normally a second mammogram is obtained.
If the 2nd mammogram suggests an abnormality ( cancer?) in the breast, a biopsy is performed by an oncologist and based on the results of tissue examintion, further tests may be undertaken.
Following all of the above, the patient must be under the care of both her PCP and her oncologist as well as others.
In the US, PCP normally do not undertake the Rx-ing of medications for the patient for "cancer". This is usually performed ( + numerous other tests such as blood work) by the oncologist with additional follow- up visits to the PCP.
All to often, many women find a breast lump and immediately jump to the conclusion of "cancer". Many lumps are not cancerous and some breast abnormalities come and go as women age and their hormones fluctuate.