Cancer treatment consent

Your doctors will not be able to give you any treatment until you have given your consent. You will usually need to sign a form to say that you agree.

Giving your permission (consent)

Doctors need your permission (consent) before you have any treatment. They will give you all the information you need to make your decision. We explain this in our section on talking about your treatment plan.

You can give consent in writing when you sign a form that your doctor gives you, agreeing to a treatment. You can still change your mind after signing the form. Different hospitals have different forms.

Or your consent can be a spoken agreement with your doctor. Your doctor will record this in your medical notes.

First several expert health professionals meet to discuss your situation and the best treatment. This is called a multidisciplinary team (MDT) meeting. They look at treatment guidelines or the latest evidence for the type of cancer you have. If you have any treatment preferences, your doctor will tell them about this.

Booklets and resources

Talking about your treatment

After the multidisciplinary team (MDT) meeting, you usually meet your cancer doctor and specialist nurse to talk over your treatment options.

They should give you as much as information as you need to make your decision. No medical treatment can be given without your consent.

You may want to ask a relative or friend to come with you. They can help you to remember what was said, and discuss it with you afterwards. You need to know as much as possible before you can make any treatment decisions.

You usually make treatment decisions with your cancer doctor or specialist nurse. This is called shared decision-making. You may talk to other healthcare professionals in your MDT.

Before you give your consent, your cancer team should explain:

  • if your treatment aims to cure or control the cancer
  • the type and extent of the treatment
  • the benefits and disadvantages (risks and side effects) of the treatments, especially any significant risks
  • any other treatment that may be available, or any clinical trials that may be suitable for you
  • what is likely to happen if you do not have the treatment.

Cancer treatments can be complex, and it is hard to understand new information when you are anxious. If you do not understand, ask your cancer doctor or specialist nurse to explain it again.

You may need more than 1 meeting with your cancer doctor to decide on your treatment plan. Sometimes treatment needs to start quickly, so there may be less time to make decisions.

If you have more questions, you can arrange to speak to someone from your healthcare team again. You may also find it useful to write a list of questions before your appointment.

Sometimes, your cancer doctor will offer you a choice of treatments that are equally effective. If this happens, they will give you time to decide which treatment you would prefer. Make sure you have enough information about all the treatment options to make your decision. You may be given written information. Or your healthcare team may recommend certain websites or decision-making tools to help you.

If you decide not to have treatment

If you decide that you do not want to have treatment, your decision must be respected. But your cancer doctor needs to make sure you have had all the information you need to make your decision. You need to understand all your treatment options. Your cancer doctor or specialist nurse can explain what may happen if you do not have treatment.

You do not have to explain why you do not want treatment. But it may help your healthcare team understand your concerns and give you the best care.

Mental capacity and treatment

Mental capacity is about being able to make your own decisions. To make treatment decisions you need to have mental capacity.

This means being able to:

  • understand the information you are given to help you make a decision
  • remember that information
  • make decisions based on that information
  • communicate the decision.

Healthcare professionals must not assume you do not have mental capacity just because you:

  • cannot communicate verbally
  • are older
  • have a learning disability
  • have a physical disability, or another health condition, including mental illness or addiction
  • make a decision which they think is the wrong one
  • have beliefs they may not agree with.

If your healthcare team feels you do not have mental capacity to make a decision about treatment, they must act in your best interests. They need to know if you have:

  • made an advance decision or advance directive which explains treatments you do not want
  • a record in writing or have told someone close to you how you would like to be cared for
  • appointed an attorney to make decisions on your behalf.

If you do not have these in place, your team will ask people close to you what they think you would want. The decision about your treatment is usually made by a senior doctor or specialist nurse caring for you. They need to carefully consider what is in your best interests before they make a decision.

We have more information about mental capacity.

Booklets and resources


Healthcare professionals are not allowed to share details of your diagnosis and treatment with your family, friends or carers without your permission. They also have to involve you in any discussion about your care.

Discussions with family or friends can only happen without you if you have given permission.

There are some situations where healthcare professionals are allowed to share information. But there are strict professional guidelines on when they can do this.

About our information

  • References

    Below is a sample of the sources used in our cancer registry information. If you would like more information about the sources we use, please contact us at

    National Institute for Health and Care Excellence. Decision making and mental capacity. NICE; 2020. Available from: Last accessed January 2023.

    General Medical Council (GMC) Ethical guidance - Decision making and consent, November 2020. Available from Decision making and consent - professional standards - GMC ( Last accessed January 2023.

  • This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been approved by members of Macmillan’s Centre of Clinical Expertise.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

  • use plain English
  • explain medical words
  • use short sentences
  • use illustrations to explain text
  • structure the information clearly
  • make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.

Date reviewed

Reviewed: 01 July 2023
Next review: 01 July 2026
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.