Key points
- Radiation therapy is an adjuvant, localised therapy treatment used to reduce the risk of breast cancer recurrence.
- It can be used in early and advanced breast cancer, as well as in the treatment of ductal carcinoma in situ (DCIS).
Radiation therapy
Radiation therapy is a localised treatment that uses high-energy x-rays to disrupt the DNA in cancer cells, to destroy or inhibit their growth. This treatment is typically used after surgery and chemotherapy to reduce the risk of local recurrence within the breast or axilla.
International clinical trials have shown that breast-conserving surgery (BCS) and radiation therapy together is as good as mastectomy in reducing risk of local recurrence.
Following a mastectomy, radiation may still be required to treat the axilla, supraclavicular fossa, internal mammary chain or the chest wall, if the cancer has high-risk features.
For ductal carcinoma in situ (DCIS), radiation following breast-conserving surgery is recommended to reduce the risk of recurrence.
In advanced breast cancer, radiation therapy is administered to reduce pain, control the growth of metastases or reduce the risk of a bone fracture.
Duration and type of treatment
Radiation therapy is most commonly delivered through external beam radiation, via a linear accelerator.
Radiotherapy treatment is individualised and carefully planned by a Radiation Oncologist. Treatments are usually 5 days per week (Monday to Friday) for up to five weeks. With this regimen, a boost (extra dose) may be applied to the tumour bed for some high-risk patients; the aim is to reduce recurrence at the tumour site.
More recently, some early low-risk breast cancer patients are offered a hyper-fractionated treatment course over five days. This short course radiation for low risk patients is as effective as current standard therapy in reducing local recurrence rate, side effects and cosmesis.
Patients eligible for this treatment protocol need to meet the following criteria:
• Invasive breast cancer (not DCIS)
• Grade 1 or 2
• No lymph node involvement
• ER+ and HER2- breast cancer
• Age: >50 years in some centres, >60 years in others.
Alternative forms of radiation therapy
APBI
Accelerated partial breast irradiation (APBI) delivers radiation therapy to a smaller area of the breast, over a few days. Advantages can include:
- reduced side effects due to lower radiation dose
- increased likelihood of breast preservation if local recurrence
- decreased treatment duration
- reduced travel time.
However, there may be an increased risk of breast recurrence with APBI, and specialised equipment and operator experience means there is limited availability. APBI techniques include brachytherapy (currently available as a public hospital treatment in Wellington) and INTRABEAM intraoperative radiation therapy (IORT), a single fraction treatment delivering a concentrated dose of radiation to the tumour removal site during surgery (not currently available in New Zealand).
Planning for radiation therapy
After an initial appointment with a Radiation Oncologist, patients will have a simulation appointment at the radiotherapy department to plan treatment. CT scans will be performed with the patient in position for treatment, to provide information about the structure of their breast and chest area to calculate an appropriate radiation plan. Immobilisation devices, such as lying on a headrest or breast-board, may be used during the simulation process to ensure the patient is correctly positioned for treatment.
Dots will be tattooed on the patient’s skin to ensure radiation is delivered to the correct area during treatment. These are small and can be removed later.
