Microscopic deposits of cancer cells may be left behind following breast cancer surgery which over time may grow and become evident as a LOCAL RECURRENCE. This occurs more commonly after a lumpectomy than a mastectomy and is the basis behind why radiation therapy is often recommended after surgery. This is why yearly surveillance is critical and why self-examination should continue even after a double-mastectomy.
These cancer deposits typically grow adjacent to the scar or attached to the chest wall muscle. If an implant is present, this will typically occur in front of the implant. Less commonly, a NEW CANCER may develop after a mastectomy in residual normal breast tissue that was left behind. This is especially pertinent in women who have a hereditary predisposition and is why the preventive surgery is called a risk-reducing operation rather than a risk-removing one.