Answer:
Yes. As with any type or form of cancer, the cancerous cells can re-appear in that area or in another area at any time. A friend of mine had breast cancer at a young age, had a double-mastectomy and was cancer-free for about a year and a half. Then, the cancer came back. There are lymph nodes under your arms and your breast tissue goes into your chest wall.
Even with a mastectomy, if they get the whole tumor out and treat with chemo or radiation, then find no signs of cancer for a year or 2 or more, unfortunately, the cancer can come back at any time.
So rock those pink ribbons and donate to Susan G. Komen!!