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2nd September 2025
What You Should Know About Breast Cancer Radiotherapy Treatment: Expert Corner with Dr. Lorraine Walsh
The appearance and feel of your breasts may change at different times throughout the month. Understanding what is normal for you can help you identify any changes early on. If you notice anything unusual, it is important to make an appointment with your GP. They can provide reassurance or arrange further investigations if needed.
Breast screening also plays a key role in early detection. When invited by the National Cancer Screening Service, attending your scheduled screening can help identify any unusual changes before symptoms arise.
Breast cancer is typically diagnosed either through a triple assessment clinic, if you have experienced symptoms, or through the National Cancer Screening Service if you are over the age of 50. During the assessment, you will undergo various diagnostic imaging tests, such as a mammogram and ultrasound, allowing your doctor to examine the breast. If further evaluation of any lump is required, a biopsy will be performed, in which a sample of the lump is taken to determine if it is cancerous.
If you have been diagnosed with breast cancer, radiotherapy is one of the treatment options available to you.
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How is breast cancer treated?
If you are diagnosed with breast cancer, surgery is typically the first step in your treatment journey. Once the cancer has been surgically removed, you will meet with a medical oncologist and a radiation oncologist to discuss additional treatment options aimed at reducing the risk of recurrence.
A medical oncologist focuses on systemic recurrence, which refers to the possibility of cancer returning either in the breast or elsewhere in the body. To address this, they may recommend intravenous (IV) or oral chemotherapy treatments.
A radiation oncologist, on the other hand, delivers a targeted radiotherapy treatment designed to reduce the chance of cancer recurring within the breast itself.
What happens during breast cancer radiotherapy treatment?
Before starting radiotherapy, a computed tomography (CT) scan will be carried out to map the cancer site, allowing for accurate delivery of treatment. This scan allows your radiation oncologist and medical physics team to create an individualised radiotherapy plan for you.
To help guide treatment, tiny tattoo dots are placed on your skin. These ensure the same area is targeted during each session. The radiotherapy itself is delivered using a machine called a linear accelerator, which directs external beam radiation to the affected area. During treatment, you will not feel or see anything.
What are the side effects of breast cancer treatment?
Radiotherapy treatment for breast cancer is generally well tolerated. Side effects can be categorised as acute side effects, which occur during or shortly after treatment, and late side effects, which may develop months or years later.
Acute side effects
Acute side effects are typically temporary and occur during radiotherapy or shortly after treatment ends. Most of these side effects resolve within three months.
- Skin changes: pinkening or reddening of the breast, similar to a sunburn, is common. If you have had a mastectomy, you may notice redness on your chest instead. This typically begins around the second or third week of radiotherapy and becomes most noticeable about a week to 10 days after treatment concludes.
- Fatigue: some individuals experience mild fatigue during radiotherapy, though this is generally not severe. If you have undergone chemotherapy before radiotherapy, you may already be feeling tired, and energy levels may not improve until after all treatment is completed.
Late side effects
Late side effects develop six months or more after treatment and can be permanent. While rare, they will be discussed with you in detail and monitored closely following treatment.
- Effects on the heart and lungs: if you are receiving radiotherapy to the left breast, there is a small risk of heart-related effects. Additionally, minor scarring of the lungs may occur, but both risks are considered very low.
- Skin changes: over time, some individuals notice slight discolouration of the breast or hardening in the area where surgery was performed. This can affect the elasticity of the breast due to the combination of surgery and radiotherapy, leading to a condition called fibrosis.
- Lymphedema: if your lymph nodes were affected by breast cancer, there is a possibility of fluid retention in the arm, known as lymphedema. This risk increases if radiotherapy is required for both the breast and lymph node region.
Being informed about possible side effects allows you to monitor any changes and seek support if needed. If you experience side effects, discuss them with your clinical team, who can guide you on management strategies. Generally, breast radiotherapy is well tolerated with minimal long-term effects.
About the Mid-Western Radiation Oncology Centre
Established in 2005, the Mid-Western Radiation Oncology Centre in Limerick is the only specialist radiotherapy treatment centre in Limerick. Operated by Mater Private Network, our expert team offers a wide range of radiotherapy treatment options. We deliver personalised care, looking after the needs of all our patients.
The above content was reviewed by Dr. Lorraine Walsh, Consultant Radiation Oncologist at Mater Private Network’s Mid-Western Radiation Oncology Centre in Limerick.
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