Bowel cancer or colorectal cancer: Understanding late effects of radiotherapy
Late side effects may happen a few months or years after treatment. They might happen once, carry on over the long term or come and go. Sometimes they cannot be cured, but it might be possible to manage them.
You might have late effects not listed here, because everyone is different. They may also be caused by a different part of your cancer treatment. It is not possible to predict if you will get them and when they might happen, which can be difficult to come to terms with. Research and support for late effects of radiotherapy is growing.
Joining a support group can be a positive way to share your experiences, feel less alone, and come to terms with the physical and emotional impact of treatment. Ask your clinical team if you need more support or have any late effects at all.
This page looks at late side effects.
How likely am I to get late side effects?
Before treatment you will discuss and sign a consent form with your clinical oncologist or therapeutic radiographer. They will tell you what to expect, and you can ask questions and discuss any concerns you have about late effects.
When you consent to treatment, you are agreeing that you understand you have a chance of getting late side effects. Your team will use words like Expected, Common, Less Common and Rare.
This table shows what these words mean.
| Wording on the consent form | % chance of side or late effect | How many patients will get this? |
|---|---|---|
| Expected | 50 to 100% | Between half and all patients |
| Common | 10 to 50% | Up to half of all patients |
| Less common | Less than 10% | Fewer than one in ten patients |
| Rare | Less than 1% | Fewer than one in 100 patients |
Most people do well for many years after their treatment, but sometimes, there can be side effects (known as late side effects) that happen much later. Here’s what you might need to know:
Possible late side effects
- Cancer-related fatigue: You might find you still have fatigue after your treatment has finished. For some people this can go on for months or years.
- Inability to achieve erections, changes in ejaculation and sperm (reduced amount or dry). Support is available if this happens. See the links below.
- Vaginal changes: Radiation can sometimes make the vagina narrower, shorter and dryer. This can make penetrative sex uncomfortable. Your clinical team can help with treatments for this.
- Fertility: Your reproductive organs (listed below) may be in, or near the treatment area. Be sure to ask if this affects you. If it does, it’s important to discuss any plans or thoughts you have about having children from the outset. Your consultant can provide advice tailored to your situation. This can be a sensitive topic, and you may not have all the answers, but having the conversation early allows you to explore your options and make informed decisions.Reproductive organs include: ovaries, uterus, fallopian tubes, cervix, vagina, penis, testes, scrotum, prostate gland, urethra, and vas deferens
- Early menopause: If your ovaries are in or near the treatment area your periods might stop earlier than usual, and you might go through an early menopause. Your medical team can help with symptoms of early menopause.
Rare and less common late effects
Small bowel problems: These are very rare (less than 1 in 100 people have them) but can include:
- Bleeding. This you may see in your poo.
- Stricture: The intestine might become narrow, making it hard for food to pass.
- Perforation: A hole can develop in the bowel wall.
- Malabsorption: You might have trouble absorbing nutrients from food.
Damage to your rectum: Again, these are rare, but something to be aware of.
- Reduced Capacity: Your rectum might not hold as much so you may need to go to the toilet more often.
- Narrowing of the anal canal – This may also affect your sex life if you receive anal sex. You may be advised to use anal dilators to stretch the anal canal.
- Urgency: You might feel like you need to go to the toilet without much warning from your body or become incontinent, but this is less common and only happens in less than 10% of patients.
- Frequency: You might need to go to the toilet more often.
- Some rectal bleeding can happen because of radiation damage to this area.
- Trouble controlling bowel movements.
- Fistula Formation: An unusual opening in the bowel. Can cause irritation and swelling around the anus, throbbing pain, smelly discharge from near the anus and a fever.
- Skin and Tissue Hardening (Fibrosis): The skin or tissues inside your body might become less stretchy and more firm over time.
- Second Cancer: There is a very small chance that you could develop another type of cancer. This is rare, and depends on lots of different factors like age, area treated and radiation dose.
What can help with these late effects?
- Managing cancer-related fatigue: Food and drink, keeping active, keeping a fatigue diary, medicine like steroids and physiotherapy may all be options for managing fatigue. Speak to your treatment or clinical team for advice.
- Keeping active: Gentle movement can help you feel better, both during and after treatment. Your treatment team can tell you what is safe for you to do.
- Bladder care: Keep drinking water and talk to your doctor if you have trouble with weeing.
- Bowel health: Professional advice on what food and drink to have can help. So can medication. Speak to your treatment team about any bowel changes and watch for any signs of blockage.
- Talk to your clinical team: If you notice anything has changed since your treatment speak to your clinical team. They can help figure out what to do next.
- Specialist care: Depending on what the side effect is, you might need to see a specialist or surgeon who knows how to treat these problems.
- Drinking fluids: Drinking plenty of fluids such as water and squash can help with fatigue and tiredness caused by your treatment. It can also help flush out toxins in your body caused by treatment. You can try diluted juice if you don’t like water.
- Skin care: The skin in the treatment area will always be more sensitive to the sun. Always protect it by covering up and use a high factor sunblock.
- Sexual changes: Help is available if treatment affects your ability to get or keep an erection or ejaculate; or if penetrative sex is difficult. Talk to your medical team and explore the links below for help and support.
- Alcohol use: Please follow the NHS guidelines on safe drinking levels and any instructions you get from your team on what is right for you, your diagnosis and your treatment. If in doubt, please ask your team.
- Stop smoking: If you are looking to stop or reduce smoking, there are services available to help you. Please see the links at the bottom of this page for more information.
Further information
Learn more about side effects and support here:
Women’s Health Concern | Confidential Advice, Reassurance and Education (womens-health-concern.org)
Bottom Line (bottomlinecharity.com)
Learn more about tools and techniques for managing sex after cancer treatment:
The Pelvic People – We’re on a mission to end painful sex
Pelvic Radiation Disease Association
https://www.cancerresearchuk.org/about-cancer/bowel-cancer/living-with/sex-life
Learn more about radiotherapy consent forms here:
https://www.rcr.ac.uk/our-services/management-service-delivery/national-radiotherapy-consent-forms/
Learn more about radiation skin reactions here:
Learn more about managing cancer fatigue:
Managing and treating cancer fatigue | Cancer Research UK
Cancer-related fatigue | NHS inform
Advice and support on reducing alcohol use:
Drink less – Better Health – NHS (www.nhs.uk)
NHS stop smoking services:
