Treatment is given as a daily fractions (Monday to Friday a total of 5 fractions per week).The treatment lasts for 3-7 weeks, depending on the fractionation and whether there is indication for a boost.
An average cardiac dose of maximally 2 Gy is striven for. If this is not achieved the target volume should be reevaluated (change of CTV to an adjusted dosage volume if this is clinically acceptable) and/or risk/benefit ratio especially considered.
- For pT1-2 lymph node positive breast cancer is usually given 25 fractions of 2 Gy (2 Gy x 25) towards the chest wall and 23 fractions (2 Gy x 23) towards regional lymph nodes. For clinically suspicion of remaining macroscopic tumor in the axilla 2 Gy x 25 should also be given towards the regional lymph nodes. For breast conserving surgery boost irradiation, 2 Gy x 8, is given towards the tumor bed, in women below 50 years of age. It is recommended that maximally 35 % of the lung should receive a dosage of 20 Gy (V20 < 35 %).
- After breast conservation for infiltrating cancer without lymph node metastases is either given 2.67 Gy x 15 (usually) or 2 Gy x 25 towards the breast. Additionally boost radiation 2 Gy x 8 is given towads the tumor bed in women < 50 years of age. Hypofractionated irradiation for left sided cancer is performed by gatting (respiratory synchronization of the irradiation). This aims at maintaining the heart outside the field limits with an average maximal radiation dose of 2 Gy. During radiation with 2 Gy x 25 towards the breast only, less than 15% of the lung should receive a maximal dosage of 20 Gy or more. For hypofractionated irradiation with 2.67 Gy x 15 this is equivalent to V18 Gy < 15%.
- Subsequently to breast conservation surgery for DCIS 2 Gy x 25 is given towards the breast. Usually less than 15% of the ipsilateral lung should receive a maximal dosage of 20 Gy or more.
- After mastectomy with tumor in the resection margin and without involvement of regional lymph nodes 2 Gy x 25 is given towards the chest wall.
- For massively non-free resection margins or remaining macroscopic tumor after mastectomy.
Radiation treatment with locally advanced/invasive breast cancer T3-4N0-3, T1-2N2-3
- After radical surgery, the radiation treatment plan is often equivalent to radiation treatment in pT1-2pN1-3 disease. 50 Gy is given toward the thoracic wall and 46 Gy toward regional lymph node stations (applies also to N0 disease). The axilla (level I and II) is not radiated if ≥ 10 lymph nodes are removed, as long as there is no known extranodal infiltration (> 2 mm) or tumor islands in the fat tissue.
To achieve optimal dosage in the skin after mastectomy a bolus should be individually considered. After breast conservation surgery (less frequently) indication for boost should be considered.