About Breast Cancer Radiotherapy

Once breast cancer is suspected, imaging of the breast tissues with a mammogram, an ultrasound and in some cases an MRI scan is required. A tissue sample is obtained to confirm the type of breast cancer, its grade, which is its aggressiveness, and whether it is a hormone sensitive breast cancer. Molecular features such as Herceptin status is also usually checked for as it can guide treatment options. The extent of the breast cancer is checked in particular if it has spread to glands or nodes in the arm pit, the collar or to a group of nodes within the chest called the internal mammary chain. At the same time, a check is done to see if the breast cancer has already spread or metastasized more widely to regions such as the liver and other sites. The most commonly used scans include a CT scan, a bone scan and a PET CT scan. Do discuss with your doctor any concerning symptoms you may have such as a persistent or new headache as that might require a scan of the brain as well.

After the above tests are done, in most cancer centers, a specialized group of clinicians called a multidisciplinary team or tumour board will review your results and give you a cancer stage. If the breast cancer has been caught early enough and not spread to distant sites, then you have a good chance of being cured. A recommendation will be made on treatment options and sequencing of these.

Surgery can be either breast conserving or complete removal of the breast with a mastectomy and you may have sampling of the nodes in the arm pit or a node dissection which removes more nodes. The tissues removed will be examined by a pathologist and sometimes further surgery may be needed. The results will be reviewed and other treatments considered and sequenced accordingly. This can include chemotherapy, Herceptin infusion, hormone treatments and radiotherapy.

There are a number of different radiotherapy options such intra-operative radiotherapy, partial breast irradiation with brachytherapy and Linac based breast or chest wall radiotherapy. I will discuss the Linac based treatments which is probably the most commonly used way to deliver radiotherapy.

Techniques of field based or 3D conformal are more commonplace but, in some situations, an Intensity Modulated Radiation Therapy (IMRT) or Volumetric Modulated Arc Therapy (VMAT) is used. There are Pros and Cons to the different approaches which the radiotherapy team will usually consider based on your situation. Other techniques such as Deep Inspiratory Breath Hold (DIBH) and Prone breast radiation therapy may be used.

DIBH is used to reduce the dose to the heart for left sided breast cancers. By holding your breath, your lung expansion pushes the chest wall away from the front of the heart which then reduces the dose the heart receives from the left breast or left chest wall radiotherapy. Large breasted women may benefit from having their radiotherapy in the prone position. This is where the treatment is delivered with you lying on your tummy as this separates the breast tissue from the skin and may also reduce the dose to the heart and lungs. Discuss the availability of such techniques at your treatment center.

Most breast cancer treatments are 15 sessions, over 3 weeks but may also be 25 sessions, over 5 weeks. If extra dosing is required to target the surgical bed, a breast boost over a week is also added in. More recently, studies have shown that in select women, compacting the radiotherapy into a 1-week long duration, with 5 sessions is also possible. The areas to be targeted with radiotherapy are the remaining breast tissue or chest wall and at-risk nodal regions in the arm pit, the collar or the internal mammary chain on the affected side.

A radiotherapy planning session is required and, in that session, the breast tissue or chest wall area may be marked out. Special techniques such as DIBH may be used and a CT simulation scan is done. Your radiation oncologist and the radiotherapy team then design and plan your treatment. 

The side effects you experience are dependent on a number of factors such as the treatments you’ve had, previous radiotherapy, underlying medical conditions and function amongst others. It’s best to discuss this with your radiation oncologist. Common side effects can include; fatigue, skin inflammation, peeling, hair loss in the arm pit region, breast/ chest wall discomfort and swelling. Some women may develop a new cough due to pneumonitis as well. Ongoing side effects can include ongoing skin and breast tissue changes. This can include color changes and breast size changes as well as firmness of the tissues. Persistent breathlessness due to scarring of the lungs is an uncommon side effect. Shoulder pains may be experienced by some women as well. If the collar region is targeted, some women may experience a sore throat and swallowing difficulties. There may also be an uncommon risk of injury to the nerves of the arm called the brachial plexus if the collar region is targeted. Left sided breast cancer may have an increased risk of heart disease although the incidence of this is low. Lymphoedema of the arm may occur as an ongoing late side effect and you may need help with compression stockings to minimize the swelling. Rib fractures can occur rarely as can a second cancer, which tends to occur many years later if at all.

There are a number of factors to take into account when guiding the treatments best suited for your breast cancer and radiotherapy is an important aspect to consider as well. More information can be found on the Targeting Cancer website, and the EVIQ website. I hope this information will help you and do recommend you clarify any concerns or further questions you have with your oncologist.

© Ramesh Pandey March 2025