Irradiation or radiotherapy will usually be administered after surgery for breast cancer, depending on the type and size of the original tumor. Radiation therapy is a topical treatment that reduces the chance of the tumor returning. The irradiation is done at the level the breast, or in case of mastectomy, at the level of the chest wall. Sometimes an extra dose or boost must be administered on the tumor bed. If the axillary glands are affected, it may be necessary to also irradiate the armpit.

Depending on the proposed treatment schedule, the irradiation session is given either daily or every other day. Where treatment used to last up to 7 weeks, it has now been shortened to a maximum of 2 to 3 weeks. After all, studies have shown that a higher dose can be safely administered at the same time. In addition, the boost can now be done simultaneously with the rest of the irradiation (simultaneously integrated boost), so it no longer needs to be added afterwards.

Due to the improved techniques, side effects such as skin burns are greatly reduced. In less than 10% of the patients, "moist desquamation" or burning is still seen. Moreover, this is often limited to small regions, very different from the extensive burns in the past. General fatigue, redness of the skin and swelling of the chest may still occur. Scarring or fibrosis can occur many years after radiation, causing the breast to feel firmer or to shrink in volume. The skin can also become discolored. Irradiation to the heart and lungs is kept as low as possible, both by radiation techniques and by an adapted radiation position, to avoid damage to these organs.

Just like axillary surgery and chemotherapy, radiation to the armpit can cause lymphedema of the arm. Both for the prevention and treatment of lymphedema you can visit the lymph clinic, a multidisciplinary collaboration between gynecologists, plastic and reconstructive surgeons, vascular surgeons, radiotherapists and physiotherapists.