Radiation therapy uses a high energy beam to kill cancer cells in a precise, efficient and safe manner. It is indicated in all patients who undergo lumpectomy and some patients who have mastectomy. Radiation therapy is delivered to the specific area through 2 different means:
- External beam – radiation is directed from a machine outside the body
- Internal beam – radioactive material, such as pellets are placed inside the breast, this is also known as partial breast radiation.
External beam radiation is typically given to the whole breast 5 days a week for 6 weeks. A “boost” to the lumpectomy site is given for an additional 5 days. Partial breast radiation is generally given twice a day for 5 days then the catheter or balloon is removed.
Radiation After Lumpectomy
Patients may wonder why radiation is required if the entire cancer tumor has been removed with clean margins during a lumpectomy. Even with perfect surgery, the cancer may come back in the same breast. Radiation therapy significantly reduces this risk of recurrence. Recurrence after radiation is rare and requires mastectomy.
Radiation After Mastectomy
The majority of patients who undergo mastectomy do not require radiation. Some patients with large or multiple tumors, significant lymphovascular invasion (e.g. cancer cells that travel outside of the tumor), and more than 3 positive axillary lymph nodes have a higher rate of recurrence, even after mastectomy. Radiation in these patients dramatically decreases the risk that a new cancer will occur in the same breast.