Cancer Loyalty Card Study 2 (CLOCS-2)

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.

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.