Radiation therapy is given to breast cancer patients after a lumpectomy or partial mastectomy in order to reduce the likelihood of a local recurrence–to prevent the tumor from growing back in the area where it was removed. Radiation destroys single or very small clusters of cancer cells that may be left after surgery. Radiation therapy involves daily treatment for a few minutes each visit (Except for the first visit, which can last longer). A patient is typically seen 5 days per week for 5-6 weeks.
The common side effects of radiation therapy include:
swelling or a feeling of heaviness on the breast
sunburn-like changes to your skin
Changes in the skin usually disappear within 6 to 12 months, although for some women they will persist longer. Radiation is sometimes associated with the development of lymphedema. The side effects from radiation are cumulative, so you’ll probably not experience many of these difficulties until the third or fourth week of treatment.