A study looking at how people manage symptoms that could be cancer (CLOCS-2)

Cancer type:

Bladder cancer
Bowel (colorectal) cancer
Liver cancer
Oesophageal cancer
Ovarian cancer
Pancreatic cancer
Stomach cancer
Vulval cancer
Womb (uterine or endometrial) cancer





This study is looking at the products people buy to help with vague symptoms that could be cancer. These symptoms might include pain, indigestion or feeling full. 

It is open to people with certain types of cancer. See 'who can enter' to find out who can join.

The team are also looking for people who don’t have cancer to take part. 

This study is supported by Cancer Research UK.

More about this trial

Some cancers are diagnosed late when the cancer has already spread. Cancer that is diagnosed at a later stage can be more difficult to treat. Researchers are looking at ways to help spot these cancers earlier.

People often choose to take over the counter medications to manage their symptoms. They buy these products rather than see their GP. This is because the symptoms of these cancers are often vague and similar to other common conditions. This is particularly the case when these cancers are in the early stages. 

In this study, researchers are looking at the painkillers, digestive products and natural remedies that people buy. They are also looking at how often they buy them. To do this the researchers are using the information found on store loyalty cards.

Store loyalty cards record the items people buy. Researchers can track what people have bought. They think the information about what people are buying to treat early cancer symptoms is useful. It might help identify these cancers a few important weeks or months earlier. This could prompt people to seek help sooner from their doctor. 

There are 2 groups in this study. One group is for people with cancer. The other group is for people who don’t have cancer.

The main aims of the study are to:

  • compare the 2 groups of people and see if there is a difference in the products they buy
  • see if it is possible to use the information on the cards to develop a way to help diagnose cancer earlier

Who can enter

The following bullet points are a summary of the entry conditions for this study. Talk to your doctor or the study team if you are unsure about any of these. They will be able to advise you. 

Who can take part

For those who have cancer 
You may be able to join this study if you have one of the following types of cancer:

As well as the above, the following must also apply. You:

  • were diagnosed with cancer within 2 years of joining this study and someone in your household has a loyalty store card at Tescos or Boots 
  • live in the UK
  • are at least 18 years old

For those who don’t have cancer
You may be able to join this study if all the following apply. You:

  • or someone in your household has a store loyalty card at Tesco or Boots
  • live in the UK 
  • have not been diagnosed with cancer within 2 years
  • are at least 18 years old

Trial design

This study is taking place in the UK. The researchers need 1,500 people to take part:

  • 750 who have cancer
  • 750 who don’t have cancer 

All the study information and questionnaires are available in English, Punjabi, Gujrati and Tamilian.

People with cancer
You can volunteer to take part in this study by contacting the study team. 

The study team or your GP will send you a link to the CLOCS-2 study survey. Once you click the link, you will be directed to the information sheet. This describes the study in detail.  

If you decide to take part, you will complete a consent form Open a glossary item and a short questionnaire online.  This is all done online.

The survey asks you a wide range of questions regarding your health, including the following:

  • if you have had children or not (this only applies to women)
  • about your cancer history 
  • about any medical conditions you have
  • about your diet and how physically fit you are 
  • if you smoke 
  • about your loyalty card use

People who don’t have cancer
You can volunteer to take part in this study by contacting the study team. 

Your GP can also invite you to take part by sending you a text message. If you decide to take part, you will complete a consent form and the online questionnaire as described above. The only difference is that your questionnaire won’t include questions about a cancer diagnosis. 

Store loyalty cards (both groups)
The study team ask the store for the data from your loyalty card. This includes information about the types of medicines, such as paracetamol, that you buy. They also look at when and where you bought it.

The study team requests this information for up to the past 6 years. 

This doesn’t include information on NHS prescriptions or any information that can identify who you are.

Hospital visits

You don’t have any hospital visits if you take part in this study. 

Side effects

Some people might find it upsetting to think about some of the issues in the questionnaire. 

Please talk to a healthcare professional if you are worried about any symptoms you have.



Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Dr James Flanagan

Supported by

Cancer Research UK (Early Detection Primer Award)
Imperial College London

Other information

You can contact the CLOCS-2 study team by email to volunteer to take part in the study. The email address is clocs@imperial.ac.uk.

If you have questions about the trial please contact our cancer information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:


Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Last reviewed:

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