Frequently Asked Questions


Q: Why are you looking at women’s shopping habits?

A: When we conceived the idea for the pilot project in 2015 and later further supported by self-reported evidence from previously diagnosed patients, it was apparent that women might manage their symptoms prior to diagnosis using over-counter medication or by gradually changing their health related behaviours. The Cancer Loyalty Card Study (CLOCS) aims to understand how women are managing changes in their bodies before they recognise their symptoms as something that might require medical attention. Subsequently, CLOCS aims to validate whether shopping habits recorded in loyalty card data can be used as a tool to support early diagnosis.


Q: What is the advantage of diagnosing ovarian cancer earlier?

A: Unfortunately, many women get diagnosed late, with stage three or stage four ovarian cancer. The five year survival rate for stage two cancer is 68% and drops down to only 27% at stage three and 13% at stage four. Many women are also diagnosed at emergency services once their symptoms had become debilitating, and are often too unwell to even undergo standard treatment. Therefore, if women tend to manage their symptoms based on their previous experience, information about how often and what products women may purchase to self-manage potential early symptoms could help identify ovarian cancer those crucial few weeks earlier, and hopefully diagnosed at an earlier stage. Finding ovarian cancer even just a few weeks earlier could make all the difference in outcome.


Q: Why are there currently delays in ovarian cancer diagnosis?

A: Currently, there is no diagnostic test with high accuracy for symptomatic women or an organised national ovarian cancer screening programme that can be used to help detect ovarian cancer early among asymptomatic women. These are still being widely investigated, and trialled. Equally, the ovarian cancer symptoms and their presentation are often vague and inconsistent. This is usually the main issue for earlier diagnosis of ovarian cancer for health care professionals.  Likewise women may delay seeking help from health professionals because they might have felt that the symptoms were manageable using home remedies or using over-the-counter medication such as pain killers or indigestion tablets. Furthermore, women who had experienced a symptom or symptoms associated with ovarian cancer had reported that "not wanting to waste GPs' time", lack of concern, normalising symptoms and competing time demands hinder seeing a health professional in a timely manner. While there has been efforts to reduce delays in help-seeking with public health campaigns, evidence shows that greater knowledge of symptoms of ovarian cancer alone do not always facilitate earlier presentation in primary care.


Q: How common is ovarian cancer?

A: There are around 7,400 new ovarian cancer cases in the UK every year, that's 20 every day.


Q: What are the symptoms?

A: Symptoms of ovarian cancer are vague and can be associated with other much more common illnesses and some can be alleviated by over-the-counter medications. However, if experienced as frequently as 12 or more times a month, the following symptoms could be related to ovarian cancer:

  • Feeling full more quickly
  • Decrease in appetite
  • Persistent bloating
  • Weeing more often
  • Pain in your tummy (abdomen)

 If you are concerned about symptoms you are experiencing, please seek help and advice from health professionals.


Q: Why now and what it the benefit of this research? 

Following this study it will be essential to validate if commercial data can be used for health research purposes and ovarian cancer is a good case study for this due to its nature. Once we understand the data better using individual data, there will be opportunities to explore this data further for other cancers, obesity, and other health conditions. We are in the process of developing the CLOCS Prospective Cohort Study that would be the most appropriate scientific method to validate our results. 


Q: How will you inform the public if you identify that increased purchases of certain products could be a warning sign?
It will be important to identify how to communicate potential risk back to individuals if our study shows a pattern that could indicate ovarian cancer. We don’t know what would be acceptable to the public yet. It can be an individual feedback via a trusted source or a public health campaign. This feedback method would be informed by the research evidence and designed with the public opinion. Future projects can test if the feedback method can reduce delays in presentation in primary care and facilitate earlier diagnosis using randomised controlled trials.


Q: Will you be diagnosing women with cancer? 
A: It is important to note that CLOCS is not offering a method to detect cancer or diagnose patients. We are investigating a dataset that may be useful to understand how women may manage symptoms of ovarian cancer objectively rather than using subjective self-reports. If there is a significant pattern identified in women with cancer compared to those without, we would still need to test this prospectively in a population who have yet to be diagnosed with ovarian cancer. This combined with health communication strategies may help reducing delays in diagnosis


Q: How has COVID affected the CLOCS project?

A: CLOCS has adapted new strategies during the height of the pandemic to ensure that recruitment can be continued once NHS sites are reopened for research. This include remote data collection for those who are shielding by the research nurses. We have also paused recruitment online when it was necessary to support researchers who are investigating impact of COVID-19 on the public. We added a new question to the questionnaire to be able to adjust for increasing use of online shopping during the lockdown as well as being able to adjust for potential purchases relating to COVID-19 status. We have a blog on our website regarding these changes (


Q: Will retailers know if loyalty card holders have cancer?

A: The retailers will never be made aware of the health status of CLOCS participants or have access to the data.   


Q: Why do you need ID verification documents from me?

A: To be able to request your data on your behalf from the retailers, we are required to confirm your identification and match the name on the consent forms using a proof of address and a copy of ID. We cannot request data without this process. This is in line with your right to data portability rights under GDPR, and to protect your data in case someone else took part in this study on behalf of you.


Q: How will my ID verification documents be stored? 

A: Your ID verification documents will be encrypted and stored in Imperial College London’s ISO27001 certified secure environment – the “Secure Enclave" – with access limited to the research team.  A member of the CLOCS research team will review your name and address on the documents you provided, confirm they match those on your consent form, and then they will be permanently deleted after we have received your purchase history from the retailers. You can read more about this and data security on our website under About Your Data.


Q: Why are you working with these retailers and not others?

A: We would very much like to work with other retailers on this project to increase the depth of the data for each individual, as people may use other retailers available at the time to buy certain products. We are currently also asking our participants which other loyalty cards they have, and the reason we have not requested consent for these is that we have not been able to establish a relationship with other retailers. If any other retailer would like to collaborate and support this project, please contact us via


Q: How do you deal with people who don’t use their loyalty card all the time, and those that are buying for others in the household?

A: The CLOCS questionnaire asks participants about how often they use their loyalty card when shopping so this can be taken into account in analysis.  CLOCS will also ask participants about the number of individuals in their household in order to take into account the likelihood that purchases are for the participant or for others in the household.