Cancer Loyalty Card Study 2 (CLOCS-2)
(CLOCS-2)
Cancer Loyalty Card Study 2: a Retrospective Observational Case-Control Study
1 other identifier
observational
2,900
1 country
1
Brief Summary
Cancer is one of the leading causes of mortality worldwide and is responsible for an estimated 9.6 million deaths yearly. Cancer-related deaths can be reduced if patients are diagnosed and treated early. Delay in cancer diagnosis can occur at any point along the diagnostic spectrum, from the first observation of symptoms to the start of treatment. Diagnosing cancer when it is still at an early stage, before it has spread, gives surgery, radiotherapy and other treatments the best chance of working. Therefore, early diagnosis is the most important way to improve cancer outcomes.Most of the cancers usually presents with vague and non-alarming symptoms. Most individuals are diagnosed late when the cancer has already spread, and the prognosis is poor. There are over 200 different types of cancer that can cause many different signs and symptoms. Sometimes symptoms affect specific body areas, such as abdomen or skin. But signs can also be more general, and include weight loss, tiredness (fatigue) or unexplained pain. The type of symptoms varies from person to person. The major reasons for not presenting to the GP with symptoms such as these are "not wanting to waste the GP's time" and normalisation of these symptoms. The persistence of a symptom, social influence and awareness encourage help-seeking behaviours in primary care. However, few believe their symptom(s) might be a sign of cancer. Consequently, people might choose to self-manage their symptoms by using over-the-counter medication, and to seek advice from other sources, (pharmacists, family, internet), rather than a primary care physician. RATIONALE FOR CURRENT STUDY An early cancer diagnosis is essential for receiving treatment as early as possible to have the best chance for successful treatment. Early diagnosis of cancer can be challenging. Sometimes, the cancer symptoms resemble common illnesses and could resolve with the use of over-the-counter medications and other remedies until they become persistent or debilitating. The present study focuses on ten cancer forms: colon, oesophageal, stomach, liver, bladder, uterine, vulval, ovarian, endometrial and pancreatic. Patients diagnosed with the cancers mentioned above often report experiencing vague symptoms (such as abdominal or back pain, indigestion, feeling full etc). They often use over-the-counter medication to manage their symptoms before seeing a doctor. Information about how often and what products participants purchase (e.g. pain killers, digestive products and natural remedies) to care for these symptoms could help identify these cancers a few crucial weeks or months earlier and encourage people to seek help sooner from their doctors.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P75+ for all trials
Started Feb 2026
1 active site
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
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Study Timeline
Key milestones and dates
First Submitted
Initial submission to the registry
June 3, 2024
CompletedFirst Posted
Study publicly available on registry
June 6, 2024
CompletedStudy Start
First participant enrolled
February 4, 2026
CompletedPrimary Completion
Last participant's last visit for primary outcome
February 1, 2027
ExpectedStudy Completion
Last participant's last visit for all outcomes
April 1, 2027
March 25, 2026
March 1, 2026
12 months
June 3, 2024
March 24, 2026
Conditions
Keywords
Outcome Measures
Primary Outcomes (1)
Purchase behaviours (purchase of pain relief medications) assessed by Statistical Model
The primary outcome of the CLOCS-2 will be to define the time by which the cases and controls are statistically significantly (p≤0.05) different in their purchase behaviours leading up to a cancer diagnosis on a population level.
3 years
Secondary Outcomes (3)
Alert about Cancer symptoms assessed by purchase behaviour
3 years
Development of risk profiles for each cancer type
3 years
Development of predictive model to assess utility of purchasing behaviours
3 years
Study Arms (2)
Cases
Participants diagnosed with cancer.
Controls
Participants not diagnosed with cancer.
Interventions
Participants will complete a brief online questionnaire at REDCap about their health, clinical history and lifestyle choices. The participant will only need to provide a photo ID and utility bill for ID verification, if the retailer cannot match participant details. After recruitment the participants purchase history in the past 6 years will be requested from the retailers.
Eligibility Criteria
Adults aged ≥18 years old, who own at least one participating high street retailer loyalty cad in their household. Among these individuals, those who have been diagnosed with any form of cancer as mentioned above (can join the CLOCS-2 as cases, and those who have no prior cancer diagnosis from the list of cancers mentioned above are eligible to join as controls.
You may qualify if:
- Individuals aged \>18 years of age
- Individuals must be residing in the United Kingdom at the time of giving informed consent
- Individuals must be registered with an NHS GP Practice
- Individuals must meet the criteria of ONE of the groups. For example, to be eligible for Group 1 (Cases), individuals must have been diagnosed with one of the following cancer types in the last 24 months: Bladder, colorectal (bowel), endometrial, liver, oesophageal, ovarian, pancreatic, stomach (gastric), uterine, or vulval; whereas for Group 2 (Controls), individuals must not have received a cancer diagnosis of any type in the last 6 years (except where the diagnosis was of non-melanoma skin cancer).
- Individuals must be a primary registered cardholder\* of one of the loyalty cards listed below, and consent to share their loyalty card data with the study team
- Tesco Clubcard
- Boots Advantage Card
- Provision of written informed consent
- Willing and able to comply with all required study activities
- The primary registered card holder, i.e., the person who is named on the loyalty card account, must also enrol into the study, if someone other than the registered primary card holder from the same household, wants to take part in the study.
You may not qualify if:
- Individuals under the age of 18 years
- Non-UK residents, at the time of giving informed consent
- Individuals without an eligible loyalty card, or who have no one in their household who has an eligible loyalty card
- Individuals who are not the primary registered cardholder in their household and where the primary registered loyalty card holder is not willing to join the study, and/or where the primary registered cardholder does not make purchases for or on behalf of the individual
- Individuals will not be able to join as a case if:
- they have been diagnosed with an eligible cancer type more than 24 months ago (except where the diagnosis was non-melanoma skin cancer).
- they have received an ineligible cancer diagnosis within the last 6 years except where the diagnosis was non-melanoma skin cancer).
- Individuals will not be able to join as a control (Group 2) if:
- o they have received any cancer diagnosis in the last six years (except where the diagnosis was non-melanoma skin cancer).
Contact the study team to confirm eligibility.
Sponsors & Collaborators
- Imperial College Londonlead
- University of Birminghamcollaborator
- University of Nottinghamcollaborator
- University of Central Lancashirecollaborator
- Cancer Research UKcollaborator
- Imperial College Healthcare NHS Trustcollaborator
Study Sites (1)
Imperial College Healthcare NHS Trust
London, United Kingdom
MeSH Terms
Conditions
Condition Hierarchy (Ancestors)
Study Officials
- PRINCIPAL INVESTIGATOR
Dr James Flanagan
Imperial College London
Central Study Contacts
Study Design
- Study Type
- observational
- Observational Model
- CASE CONTROL
- Time Perspective
- RETROSPECTIVE
- Sponsor Type
- OTHER
- Responsible Party
- SPONSOR
Study Record Dates
First Submitted
June 3, 2024
First Posted
June 6, 2024
Study Start
February 4, 2026
Primary Completion (Estimated)
February 1, 2027
Study Completion (Estimated)
April 1, 2027
Last Updated
March 25, 2026
Record last verified: 2026-03
Data Sharing
- IPD Sharing
- Will not share
Only aggregated and anonymised survey data will be shared with other researchers after publication. No sensitive individual level data will be shared.