Cancer Loyalty Card Study 2 (CLOCS-2)

Purpose and Design

The Cancer Loyalty Card Study-2 (CLOCS-2) addresses whether or not data already collected by high street retailers can detect significant changes in cancer patients' purchase behaviours before their diagnosis. The aim is to conduct a case-control study of cancer patients matched with participants without these cancer types. 1450 recently diagnosed cancer patients and 1450 participants as controls will be recruited and up to six years of prior purchase data will be collated.

Recruitment

Participants, 18 years or older, with any of the aforementioned cancer forms and having at least one of the participating high street retailer's loyalty cards from Tesco or Boots in their household, will be recruited through the GP invites, NHS cancer clinics and Be Part of Research.

All participants registering in the study and not holding the primary ownership of the loyalty cards from Tesco or Boots must register in the study along with the primary owner of the loyalty card from the same household. All the collected data will be safeguarded in a secure enclave with limited access to the CLOCS-2 team.

Consent

All participants will be given the information sheet and consent form through a REDCap link shared through messages sent by GP, cancer clinics or Be Part of Research. They can take as much time as they need to read through the information sheet. If they choose to participate, they can complete the consent form whenever convenient and fill it out online at REDCap.

Methods

Loyalty card holders with primary ownership of at least one of the participating high street retailers loyalty cards from Tesco or Boots and their family members living in the same household are eligible to participate in CLOCS-2. All participants will be invited to join the study by invites (sent through text messages from GP, cancer clinics or Be Part of Research) and can choose to sign up via a link provided in invites that leads to REDCap. People over 18 years of age and with any form of cancer as listed earlier and who use at least one of the participating high street retailer's loyalty cards in their household will be recruited as cases. Whereas people over 18 years of age, without the diagnosis of these cancer types and using at least one of the participating high street retailer's loyalty cards in their households will be recruited as control participants.

Consenting participants will complete a brief online questionnaire at REDCap about their health, clinical history and lifestyle choices. To adhere to participating high street retailers' policies, only participants whose details cannot be matched to that of the retailers' will need to provide a photo ID and utility bill for ID verification.

The tentative participant recruitment date is 01/11/2025. Once the participants are recruited in the study, their past six years of purchase history will be requested from Tesco/Boots from the recruitment date. This data received from these high street retailers will be non-identifiable pseudonymised data. Participant identity will be linked to the analysis datasets only through a unique barcode assigned when completing the recruitment questionnaire, meaning the data will be pseudonymised. The only identifiable information will be on the consent form and the participant barcode. Retailer and questionnaire data will only be linked via the pseudonymised participant barcode.

If participants consent to be re-contacted by the CLOCS-2 team for future studies or loyalty card detail clarification, they can opt for it in their consent forms. No further action is needed from participants once they complete their consent form and questionnaire (and clarify loyalty card details if necessary). Participants will be provided with the study's website and encouraged to visit the study's website for updates.

Inclusion criteria

(ALL):

• 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.

Exclusion criteria

(ALL):

• 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

Exclusion criteria

(CASES):

• 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).

Exclusion criteria

(Controls):

• 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).