Radiation Therapy of Breast Cancer
Curative radiation therapy usually includes CT-based drawing of target volumes. This drawing is the basis for dose planning and field definition. The adjustment of radiation field is at present only rarely performed manually.
Radiation therapy after breast conservative treatment
After the tumor is removed by breast conservative surgery, there may still be remaining cancer cells in the breast. Therefore, it is recommended that the entire breast is irridiated. To minimize the risk for recurrence, infiltrating tumors should be removed with free resection margins (“ink not on tumor”) before radiation is started. For DCIS in contrast, a 2 mm minimum (rounded to whole mm) distance between DCIS and the resection margin is required. If these criteria are not met, it is recommended to do a re-resection before radiation treatment, both for invasive carcinoma and DCIS. More narrow margins are accepted if a resection is performed to the skin and down to the muscle fascia.
The present results clearly support the basis for equalization of hypofractionated radiation (2.67Gy x 15) and conventional radiation (2 Gy x 25) for pT1-2 pN0 infiltrating breast cancer treated with BCT.
Radiation therapy after mastectomy
Radiation therapy is recommended in the instances where a mastectomy is performed for invasive breast cancer, where microscopic resection margins are uncertain or not tumor-free.
Radiation therapy for metastases to lymph nodes
Radiation therapy to the breast/chest wall and regional lymph nodes is recommended for metastasis > 2mm to an axillary lymph node.
Invasive breast cancer stage III (T3-4N0-3, T1-2N2-3)
This patient group is very heterogeneous. It is important that the individual patient is assessed by both a surgeon and an oncologist before treatment is decided. The patient should be referred to a regional oncology department for assessment of multimodal treatment.
Most often, neoadjuvant chemotherapy is followed by surgery before radiation therapy is relevant. In certain cases, operability is not reached by the neoadjuvant treatment. In these cases, radiation therapy may be performed without previous surgery.
Radiation therapy without previous surgery
Radiation therapy without previous surgery is used occasionally for very large tumors or inflammatory breast cancer, or if the patient refuses operative treatment. This approach may be an alternative if the patient cannot undergo surgery for medical reasons. In these cases, the radiation treatment plan will be individualized.