In patients who undergo a mastectomy, radiotherapy is recommended in certain higher risk patients. The role of radiotherapy to the chest wall after a mastectomy was established in a large study. This study showed that there was significant local control benefit, especially for patients with more than 3 positive lymph nodes. However, these studies were conducted many years ago when chemotherapy and targeted therapy were less effective than today’s drugs. Recent years, more studies have been done to find out if radiotherapy not just to the chest wall, but to the surrounding lymph nodes is effective. The MA 20 and EORTC 22922 trials showed that there was a small benefit in regional nodal irradiation, and the benefit was more evident in patients with higher risk disease. Hence, patients with positive lymph nodes should discuss this option with their radiation oncologist.

Regional nodal irradiation (RNI) is a component of breast cancer treatment that involves delivering radiation therapy to the regional lymph nodes in addition to the primary tumor site in the breast. This approach is typically considered for certain breast cancer patients, especially those at higher risk of regional nodal involvement. The decision to include regional nodal irradiation in the treatment plan is often based on factors such as the extent of lymph node involvement, tumor characteristics, and the overall risk profile of the patient.

Fields of Radiation:

• The radiation fields for RNI typically encompass the regional lymph nodes, which may include the axillary, supraclavicular, and internal mammary lymph nodes.
• The fields are carefully planned to ensure that the radiation targets the at-risk lymph nodes while minimizing exposure to surrounding healthy tissues.

In a large recent meta-analysis published in November 2023, of more than 10 thousand women with breast cancer requiring adjuvant radiotherapy, radiotherapy significantly reduced breast cancer mortality. Regional nodal irradiation ( RNI) benefitted patients with >3 axillary nodes the most. With today’s improved technologies, e.g. Volumetric Modulated Arc Therapy, and breath-holding set-up; radiotherapy is safe as it allows the heart dose to be lower and hence a more comprehensive coverage of the internal mammary nodes.

Talk to your radiation oncologist about regional nodal irradiation. If you have certain risk factors, comprehensive nodal irradiation is beneficial. Also, find out about techniques available at your center to maximize nodal coverage and minimize cardiac doses.