Question: What is the difference between local and systemic therapy?
Answer: Local and systemic therapy in essence address two separate problems that are faced for patients with cancer. Local therapy is designed to prevent a local recurrence of the cancer.
That is to say, getting sufficiently wide margins around the cancer so that one has a reasonable certainty that the cancer will not re-grow locally.
Systemic therapy involves therapy that's designed to kill cancer cells that have fled the breast by way of blood vessels to organs elsewhere in the body.
Patients with breast cancer don't die of cancer in the breast, they die of cancer outside the breast, in organs such as lungs, liver or bone.
For patients where we suspect systematic dissemination of the cancer, in essence microscopic spread to other organs, we frequently will give the patient a therapy that's designed to kill off those microscopic cancer cells before they can grow large enough to threaten the patient's life.