Postoperative radiation therapy requires adequate removal of the primary tumors and completed axillary dissections (sentinel node or adequate axillary dissection levels I and II). A ≥ 5 mm tumor-free margin to the sides should be for the goal during surgery. Re-resection is however not necessary if the resection margins are tumor-free in("ink not on tumor"). Thus there are no specific requirements on the resection margins. If there is uncertainty whether the resection margins are free, the patient must be re-operated and have a re-resection or mastectomy. The exception is when the tumor is localized close to the thoracic wall or to the skin, where smaller margins are accepted, if resected to the fascia or to the skin.
Postoperative radiation therapy should not be given simultaneously with adjuvant chemotherapy. Radiation therapy must begin within 3-4 weeks after chemotherapy is finished.
Endocrine treatment and trastuzumab (Herceptin®) can be given simultaneously with radiation therapy.
For infiltrating breast cancer:
- After breast conserving surgery
- For large primary tumor (T > 50 mm)
- For non-radical surgery (after mastectomy)
- For lymph node positive disease (except for involvement of only intra-mammary lymph node without any other lymph node involvement)
- All grade II/III and grade I > 10 mm with BCT
- Non-radical surgery (after mastectomy)
Radiation therapy after breast conservative treatment
DCIS (all grades II/III, grade I > 10 mm)
Radiation treatment is performed as two tangential fields. The entire breast (not the chest wall) is defined as the target volume. The medial field border will be close to the midline. The radiation must include the lateral part of the breast. Upwards, the field will extend to the sternoclavicular joint, and downwards to 1-1.5 cm under the inframammary fold.
Invasive breast cancer pT1-2pNO
Radiation treatment is performed as two tangential fields. The entire breast (not the chest wall) is defined as the target volume. The medial field border will be close to the midline. Upwards, the field will extend to the sternoclavicular joint and downwards to 1-1.5 cm under the inframammary fold.
To minimalize the cardiac radiation hypofractionated radiation towards the left side should be performed with gatting (breath synchronized radiation). This strives to maintain the heart outside the field borders with a maximal average dose of 2 Gy. On this basis it is accepted that during chemotherapy/immunotherapy the patient have synchronous irradiation. (the organ at risk avoids for the combination of chemotherapy and radiation dose).
Invasive breast cancer pT1-2pN1-2
If there is metastasis to one or more axillary lymph nodes and the largest metastasis is > 2mm, radiation therapy should be given toward the mammary gland and regional lymph nodes.
For elderly patients, an individual assessment is made with emphasis on comorbidity, biological age/expected survival time.
The target definition for patients in this group should, in addition to the breast, include the axillae and supraclavicular lymph nodes. In large, medial tumors, the upper parasternal lymph nodes are also included. When 10 or more axillary lymph nodes are removed, level I and II of the axilla should not be irradiated. This is independent of how many lymph nodes are tumor-involved. If the surgeon notes that there is possibility for remaining tumor in the axilla or that the lymph node involvement is very wide-spread, level I and II of the axilla should also be included in the target volume to improve regional control. The same applies if there is evidence of macroscopic extranodal extension (> 2 mm) or tumor islands in the fatty tissue, even if ≥ 10 lymph nodes are removed.
Invasive breast cancer pT1-2pNO or DCIS
The target area includes the chest wall located under the breast and the scar. Radiation treatment is performed as two tangential fields with field borders laterally in the medio-axillary line, medially in the mediosternal line, downwards to 1-1.5 cm under the inframammary fold of the opposite breast and cranially towards the sternoclavicular joint.
Invasive breast cancer pT1-2pN1-2
Radiation therapy after mastectomy is equivalent to what described for breast conservative treatment (largest lymph node metastasis > 2mm) with the following exceptions:
- A boost is not usually given after mastectomy. The target volume is the chest wall located under the breast and the incision scar, axillary and supraclavicular lymph nodes and possibly the upper parasternal lymph nodes.
- For elderly patients, an individual assessment is made with emphasis on comorbidity, biological age/expected survival time.
- To reduce the risk for local and/or regional relapse.
- To increase the survival after both breast conservative treatment and mastectomy.