Radiotherapy for breast cancer: What to expect

Posted by Sara Liyanage on 10 February 2023

Radiotherapy can sound daunting so here are our top ten pointers for what to expect. We’ve written this article from our experience as patients and we encourage you to speak to your medical team about your personal situation.

Radiotherapy is a bit of a mopping up treatment– it aims to destroy any cancer cells that may be hanging around the breast/lymph node areas. Patients can have radiotherapy after chemo or straight after surgery, this depends on the stage of cancer. Some people also have radiotherapy to their neck area to treat any lymph nodes that may have cancerous cells found in them.

It can be quite a quick process. You arrive, take everything off your top half, hop on a table, get put into position by the Therapeutic Radiographers, have your chest area and armpits zapped (whichever ones were your problem ones), hop off the table, get dressed and off you go. You may be offered a gown to wear or a specially designed breast dignity gown but some patients also choose to wear their own vest top which they can roll down while on the bed instead – whatever you’re most comfortable with. The whole process only takes around 15 minutes which is good because the room is chilly (to keep the machines at a low temperature). You can ask for a blanket or put an item of clothing over your legs. The zapping itself only takes seconds.

The zapping is done by some big machines which move around you whilst you are lying completely still on a table with your arms above your head. It is not like a CT or MRI machine at all and you rarely get close to the machine. The Therapeutic Radiographers are not in the room with you whilst the zapping is done, but they are just outside the room, can see you on the CCTV cameras and speak to you through a two-way intercom.

The zapping process itself does not hurt as there is nothing to feel, see or hear during radiotherapy.

There are different methods of zapping your boobs. You’ll be told which type you will be having by either the oncologist or a Therapeutic Radiographer at an introduction appointment. Some types of radiotherapy require you to hold your breath so that the chest wall moves away from the heart and lungs – this helps reduce their radiation dose. This is usually given when you have radiotherapy to your left breast.

You usually have to have radiotherapy every day apart from the weekend but never more than 5 treatments in a week. Although there are some hospitals that do give radiotherapy treatment at weekends.

Your oncologist determines the number of days for which you will have radiotherapy and it can be different for everyone although it is usually around 1 – 4 weeks.

Make sure you know what to expect of your radiotherapy by asking to visit the radiotherapy unit and asking questions before you start your treatment.

You will have a planning appointment at which you have a CT scan and the Therapeutic Radiographers measure you and mark some pinpoint tattoos on your chest (they look like tiny, inconspicuous, black freckles – almost as if you have just marked yourself with the tip of a black biro. The tattoos are permanent but they can fade later). These are to help the Therapeutic Radiographers to get you in the correct position when you go for your radiotherapy treatments.

Side effects tend to kick in after about a week or two of having radiotherapy, and they can peak around 10-14 days after the treatment has ended. You may get pink/red discolouration to the skin area which is zapped. This area gets very dry and itchy so needs to be moisturised (see The Do’s and Don’t’s of Rads: Top Ten Pointers). Sometimes the area can get sore or the skin damaged to a greater extent than just dryness, if this happens the Treatment Review team will help manage this for you. You will also get tired and possibly a bit achy. Some people may notice that their skin issues and tiredness continue for a number of months after radiotherapy ends.


Breast Cancer Now has a booklet on radiotherapy which you can download or order here.

If you would like to read up on some of the more scientific-y technical aspects of radiotherapy then take a look at the Cancer Research UK blog on radiotherapy.

What I’d Wish I’d Known Before Radiotherapy – a Shine article. – a website for patients who have been referred for radiotherapy to the breast or chest wall following a breast cancer diagnosis. In particular, the aim of the resources is to help patients who have been diagnosed with cancer in their breast for whom it may be beneficial to learn how to hold their breath for a short time during radiotherapy.

Radiotherapy UK – this is a charity dedicated to improving radiotherapy treatment, the aim of which is to support radiotherapy research and development and support radiotherapy professionals by providing online tools to enhance collaboration. Their website provides so informative resources for those going through radiotherapy.

Future Dreams hold a range of support groups, classes, workshops and events to help you and your carers during your breast cancer diagnosis. These are held both online and in person at the London-based Future Dreams House. To see what’s on offer and to book your place, see here.

To return to the homepage of our Information Hub, click here where you can access helpful information, practical advice, personal stories and more.

Reviewed February 2023

The information and content provided on this page has been written from a patient’s perspective then reviewed by Naman Julka-Anderson, Senior Therapeutic Radiographer (Macmillan Treatment Review Radiographer) and member of Radiotherapy UK, and also by a breast care nurse. It is intended for information and educational purposes only. It is not intended to substitute for professional medical advice. Please contact your medical team for advice on anything covered in this article. The links and/or recommendations in this article to third-party resources are for your information and we take no responsibility for the content contained in those third-party resources.


Sylvie Henry and Danielle Leslie founders of Future Dreams breast cancer support
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Sylvie and Danielle began Future Dreams with just £100 in 2008. They believed nobody should face breast cancer alone.  Their legacy lives on in Future Dreams House.  We couldn’t continue to fund support services for those touched by breast cancer, raise awareness of breast cancer and promote early diagnosis and advance research into secondary breast cancer without your help. Please consider partnering with us or making a donation.

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