Radiotherapy for rectal cancer or cancer of the anal canal

Radiotherapy is the controlled and precise use of high energy x-rays to treat cancer.

What is radiotherapy?

Radiotherapy is the controlled and precise use of high energy x-rays to treat cancer.

External beam radiotherapy is delivered using a machine called a linear accelerator (linac). It can be used in combination with surgery and chemotherapy. Treatment is usually divided up in to daily treatments of small doses (called fractions) to allow time for healthy tissues to recover from the radiation. Your doctor will discuss the type and length of your specific treatment with you.

The treatment is painless and only takes a few minutes. You will not be radioactive.

If you have any questions about treatment before you attend the department, please do not hesitate to contact us.

Important: Radiation can harm an unborn baby, it is important to let the staff know as soon as possible if you think you might be pregnant.

Preparing for radiotherapy

How you prepare for radiotherapy will vary depending on the area of your body that you are receiving treatment to. It is important that you are well hydrated; we recommend aiming to drink 1.5 to 2 litres of water each day both prior and during your course of radiotherapy treatment. Eating well and staying active is also important. Gentle exercise can help lift your mood and help prevent and alleviate fatigue.

If you currently smoke we would also recommend stopping before your radiotherapy treatment starts. Smoking can worsen side effects from radiotherapy and reduce how effective the treatment can be. Please contact the department, your GP, or local pharmacy if you would like support in stopping smoking.

Your first appointment for radiotherapy will be a planning session; this usually involves having a CT scan. The scan allows us to plan exactly where you will have your treatment and the best position for you to lie in. Sometimes we may want to do an intravenous (IV) contrast scan, this usually depends on the area being treated and will be requested by your consultant if appropriate. You may also be asked to do some bowel preparation or drink some water prior to your scan. This may be explained in your letter but the staff working in the CT scanner will explain the procedure for your scan when you arrive.

If you are worried that you will have problems with the process, please contact the department prior to your appointment.

Following your planning appointment there may be a number of weeks before you come back to start your treatment. The planning of treatment is a complicated process that takes this time to ensure the best treatment for you.

Side effects

Radiotherapy affects people in different ways and even when receiving similar treatment, people can experience different side effects. Radiotherapy is a localised treatment, which means it will only affect the specific area being treated. Its effect is also cumulative, so you are unlikely to notice any side effects straight away and any side effects will likely continue for a few weeks after the treatment has finished.


You may develop a skin reaction over the area being treated. This can vary from a mild darkening/reddening of the skin, to skin that is quite sore and can become broken. Your skin may feel tight and/or itchy and small blisters may appear.

We recommend treating your skin gently when washing/drying and regularly applying a moisturiser in the treatment area. You can use your normal deodorant and bathing products. Avoid hair removal in the treatment area if possible. Keep the area covered in direct sunlight, wherever possible, as it will be more sensitive to the sun following radiotherapy.

You will be given some cream and further information on your first day of treatment. The cream is called Flamigel. We advise you use this every day during your course of treatment even if your skin is feeling normal. It helps to prevent and delay a skin reaction from the treatment.

If you notice changes to your skin during treatment, please speak to a member of staff as soon as possible as we may give you different advice or products to use.


You may feel tired or lethargic during your radiotherapy treatment and for a number of weeks afterwards. Keeping up with your daily activities can help and a gentle daily walk can be beneficial. It is important to listen to your body; fatigue can also affect how you feel mentally. Please speak to staff if you want support with managing fatigue.


Radiotherapy can sometimes make you feel sick. If you notice this, you can try natural remedies such as food and drink that contain ginger or peppermint. If you feel that your appetite is affected, we suggest avoiding large meals and trying to eat small meals/snacks more frequently. If nausea persists or you vomit at all please contact the department as soon as possible.

Bladder problems

If you are receiving treatment to your pelvis area, then your bladder will likely receive some radiation. This can cause irritation known as radiation cystitis. Symptoms include discomfort, increased urinary frequency and urinary urgency. Please tell a member of staff if you are experiencing any of these symptoms.

Bowel problems

Again, if you are receiving treatment to your pelvis area it is likely that your bowel will receive some radiation too. This may cause loose stools and/or diarrhoea. It may also cause some abdominal discomfort. You may also experience irritation to your rectum (back passage) caused by inflammation from the radiotherapy. This can cause some discomfort when you are passing stools and a symptom called tenesmus. This is the urge to pass a motion when there is not anything there and is often confused with constipation. It is important that you try and resist straining. You may notice some rectal discharge and even some bleeding. Please ask to speak to one of the review team if you are experiencing any of these symptoms.


Radiotherapy to the pelvis will affect fertility in both men and women. Please take precautions to ensure you do not become pregnant during your treatment. Your consultant will be able to discuss any fertility concerns with you prior to treatment.


Cancer and its treatment can affect your body image and your sexuality. Your feelings may change as a result of the emotional impact and physical effects from treatment. We recognise that this can be difficult or embarrassing to talk about these feelings but please know that staff are there to support you and welcome any questions or concerns you have.

Potential late side effects

Radiotherapy can sometimes cause long-term side effects that can occur months or years after your treatment. When we plan your treatment, we do all we can to reduce the risk of these but there can sometimes be permanent changes. Your consent form will include more detail specific to your type of treatment.

Getting to the department

Please see the ULHT website for the most up to date travel and parking information

Patients undergoing treatment for cancer are entitled to free parking. You will be asked to enter your registration plate number into a screen at the oncology reception desk.

If you will have problems travelling from home each day we may be able to book hospital transport for you. Please note that if you use this service, you will likely be away from home for at least half of the day. Transport is for the benefit of patients only and escorts may only be booked in very restricted circumstances.

Useful contacts

Trust website:

Radiotherapy: 01522 572236 or 01522 572268

Oncology Assessment Unit: 01522 307841

Out of hours (Waddington Unit): 01522 307198

Colorectal specialist nurses: 01476 464822

Macmillan Information and Support Service:
Lincoln: 01522 573799; Boston 01205 446392; Grantham 01476 464978

Radiotherapy instagram: @radiotherapylincoln

Radiotherapy X: @ULH_RadTherapy

Cancer Research UK:

Macmillan:  or 0808 808 00 00