Radiation therapy (radiotherapy) is the use of ionising radiation in the form of high energy X- ray beams to kill or control the growth of malignant cancer cells. It does this by disrupting the DNA (genetic code) within these cells. It’s a localised treatment affecting only the area which is specifically targeted. Although some healthy tissue may be in the treatment area, it has the ability to repair itself, unlike cancer cells.
In early breast cancer, radiation therapy is used with the aim of eradicating any malignant or pre-cancerous cells remaining in the breast following partial mastectomy or lumpectomy. It can also be used to treat the chest wall after mastectomy if the cancer has high risk features. The regional lymph nodes in the axilla ( underarm), supraclavicular fossa (above the collar bone) or internal mammary chain (close to the breast bone) may also be treated. In these settings, large international trials have demonstrated that radiation therapy reduces the incidence of local breast cancer recurrence.
Radiation therapy is usually given after surgery, once the wounds have been able to heal. For people needing chemotherapy, radiation is given after that treatment has been completed.
External beam radiation therapy.
The commonest way of delivering radiation to the breast is with a treatment machine called a linear accelerator which delivers radiation beams from outside the body, targeting the whole breast or chest wall. The patient is positioned on a bed and the head of the linear accelerator is lined up to focus the radiation to the targeted area. At each treatment appointment additional time is taken to ensure the correct positioning of the patient prior to treatment delivery. Once correctly positioned, the treatment takes only a few minutes to deliver. The head of the linear accelerator moves around the patient, delivering the beams but patients do not feel the treatment being delivered. Although the radiation therapists leave the room while the treatment is being given, they monitor the patients on closed circuit television and through microphones in the treatment room.
What to expect:
Before treatment starts you will meet with a radiation oncologist, a cancer specialist who will plan and oversee your treatment. At this appointment, the benefits and risks of the treatment will be discussed with you so that you are able to make an informed decision about undergoing the treatment.
The next step is a planning or simulation appointment at the Radiotherapy Department. You will meet the staff involved in your care. This may include other doctors such as registrars and house surgeons, specialist oncology nurses, medical physicists, radiation therapists and support staff.
CT scans will be performed, with you in the position for treatment, to provide information about the structure of your breast and chest area so that an appropriate radiation plan can be calculated. This ensures that the most effective radiation dosage can be delivered to the targeted site while sparing unaffected tissues as much as possible.
To ensure that you are correctly positioned for treatment each day, at the time of CT simulation a variety of immobilisation devices may be used, such as lying on a headrest and breast board,that will also be used during your treatment. In addition, small ink marks or tattoos will be placed on your skin to ensure that the radiation will be focussed on the correct area each day. (These marks are very small but can be removed at a later date if you prefer)
A typical course of radiation therapy is given daily (5 days a week, excluding weekends, to allow the healthy cells to recover) for 3 to 6 weeks. The total radiation dose is divided into smaller daily doses, known as fractions, to reduce harm to healthy tissues
Intraoperative Radiation Therapy ( IORT)
A recent development in targeted breast radiation therapy is the use of INTRABEAM intraoperative radiation therapy.
This method is approved for use and covered by some insurance companies, but not yet publicly funded in NZ. It is a single fraction treatment, using an applicator to deliver a concentrated dose of radiation to the site of the removed tumour at the time of surgery. Studies show that when breast cancers recur, they mostly do so around the site of the original tumour and IORT delivers treatment to that area while sparing the rest of the breast tissue. This also reduces radiation exposure to other organs such as the skin, heart and lungs.
IORT is delivered by accredited surgeons and radiation oncologists in some private hospitals and takes about 30 minutes. Once the treatment has been delivered the surgeon continues with the operation and closes the cavity and the skin.
This may be a treatment option for carefully selected women who are having breast conserving surgery ( lumpectomy) and who fit the following criteria:
- Age 45 years or older
- Tumour size less than 3cm (on imaging)
- Node negative clinically, on imaging and sentinel node biopsy.
- Grade 1 or 2 tumour which is hormone receptor positive
This procedure is NOT suitable for women with:
- Invasive lobular cancer
- Ductal carcinoma in situ
- Multiple tumours in the same breast
- Grade 3 tumour
- Any tumour with lymphovascular invasion
- Previous breast cancer / irradiation to the breast
- BRCA mutation
Depending on the pathology results after surgery, some women may still require external beam radiotherapy to the whole breast, in which case the IORT will act as a cavity “boost” dose.
Read more information about IORT here:
Understanding Interoperative Radiotherapy - A Patients Guide
Possible side effects of radiation therapy:
Skin irritation in the treated area.
This may range from mild “sunburn” to peeling or occasionally blistering. This side effect may not develop until treatment completion. It is usually at its most severe for 1 – 2 weeks and then settles over the following 3 – 4 weeks.
It’s important to try and reduce friction between your skin and clothing to reduce the risk of skin breakdown or blistering. You will be advised how to take care of your skin.
For instance :
- No hot water, soap, lotions or other possible irritants should be placed on the skin in the treatment area.
- Wear loose, light clothing (preferably non-synthetic materials such as cotton)over the area being treated.
- Avoid heat from hair dryers, electric hot pads, hot water bottles and sun in the treatment area.
- No adhesive tapes or sticking plasters should be applied to the skin in the treatment area
Some patients choose to use a transparent, breathable, film dressing applied to the skin in the treatment area to try to reduce the skin reaction. Your radiation oncologist will be able to advise you on these products. Your radiation oncologist will also discuss with you the use of topical creams for the skin, depending on your skin reaction.
Breast heaviness, tenderness, itchiness, and swelling may occur towards the end of radiation therapy and continue for a few weeks after treatment completion.
Many people continue to work during their treatment but variable degrees of tiredness are common and may persist for a few weeks after treatment has been completed. It’s important to plan your days so that you can have periods of rest if needed. Gentle exercise such as regular walking can be beneficial.
Possible late effects:
Radiation therapy may cause the breast to feel firmer and to be slightly smaller in volume. There may be some permanent discolouration of the skin in the treatment area and visible small red blood vessels (“spider veins”) may develop.
Your radiation oncologist will discuss with you the very small risks of long term damage to normal tissues in the treatment area, such as changes in the lungs underlying the chest wall, rib fracture, heart problems if you have a left sided breast cancer, nerve damage causing weakness in the arm, or lymphoedema of the arm or breast. There is an extremely small risk of inducing a second cancer in the treatment area many years after your breast cancer radiotherapy.
It is felt that the benefit of radiation therapy using modern radiation techniques outweighs the potential risks of treatment and your radiation oncologist will discuss this with you.
Deep Inspiration Breath Hold
Fifty percent of breast cancers occur in the left breast and a small area of the heart can be exposed to the radiation field. Depending on the volume of heart treated and the dose delivered to the heart, this can increase the risk of heart disease over time.
Various techniques are used to minimise the exposure of the heart to radiation. One technique is to hold a deep breath whilst radiation is delivered, as this expands the lungs and moves the heart away from the chest wall. To more accurately maintain a deep inspiration breath hold, some centres are using the Elekta Active Breathing Coordinator (ABC) device.
Using the Elekta Breathing Co-ordinator, patients are taught to take a measured deep breath and hold it for up to 20 seconds at a time while the radiation dose is delivered. This may expand the lung sufficiently to move the heart out of the radiation field. Using the Elekta machine, patients can monitor their own breathing and the machine links to the linear accelerator ensuring that the radiation dose is only delivered when optimal breath hold is reached and maintained.
Maria Pearse’s Radiation therapy presentation:
Watch this video made by Cancer Research UK: Having radiotherapy for breast cancer: