After breast conserving surgery (lumpectomy), the usual course of radiation treats only the breast, although you may need to have nearby lymph node areas treated as well. The radiation beam comes from a machine called a linear accelerator or linac. The radiation beam is painless and treatment itself lasts only a few minutes. Treatment is delivered every day, five days a week, Monday through Friday. The full course of treatment is usually delivered over three to seven weeks.
Before beginning treatment, you will be scheduled for a planning session to map out the area your radiation oncologist wishes to treat. This procedure is called a simulation. Simulation involves having X-rays and/or a CT scan. You may also receive tiny marks on your skin, like a permanent tattoo, to help the radiation therapist precisely position you for daily treatment.
Typically, radiation therapy is done with high energy X-rays, or photons, for the bulk of the treatment. When there is a reason to focus the radiation where the lump was taken out, sometimes a "boost" will be given with electrons to treat with a less penetrating, more focused beam instead of photons.
Different techniques can be used to give radiation therapy for breast cancer. Three-dimensional conformal radiotherapy (or 3-D CRT) combines multiple radiation treatment fields to deliver very precise doses of radiation to the breast and chest wall while sparing nearby normal tissue. Intensity modulated radiation therapy (IMRT) is a form of 3-D CRT that further modifies the radiation by varying the intensity of each radiation beam. Doctors are still studying IMRT for the treatment of some types of breast cancer. Talk to your radiation oncologist for more information about the details of your treatment plan.
Recent clinical trials suggest that treatment with whole breast radiation may be shortened by treating with higher daily doses to finish in less time. Ask your doctor for details about the right dose and schedule for your case.
Additional research suggests women aged 70 or older with hormone receptor positive early stage breast cancer benefit from radiation in terms of lowering their risk of getting breast cancer again in the treated breast. This local control benefit, however, has not been shown to affect their long term survival. Because the risks and benefits of radiation differ based not only upon age but other health factors and personal preferences, discuss with your doctor whether radiation is necessary.