Health On Your Loyalty Card?

Lots of supermarkets/stores operate loyalty card schemes. Such low cost schemes basically enable supermarkets to track (and predict) the likely purchases their customers will make. An Imperial College London team were granted access to the data on the loyalty cards of 300 women. They focused on the purchases of 'over-the-counter' (i.e. non-prescription) medicines, looking for health implications (https://www.theguardian.com/society/2023/jan/26/loyalty-card-data-could-help-spot-ovarian-cancer-cases-sooner). The Imperial College study found that women, who purchased more pain killers and indigestion treatments, had an increased likelihood of being diagnosed with ovarian cancer circa 8 months later. Early diagnosis, of course, greatly improves the chances of successful treatment for this condition. This is an interesting finding but it raises several issues. Rather obviously, this type of analysis raises confidentiality concerns. The 300 women would have consented to the study but others might want to protect their privacy. Another complicating factor is that the loyalty card users may not be purchasing the medications for themselves. Many would have families and aging relatives. There's a possibility that the 300 subjects were more likely to get medical checks because they were part of this study. One of the current UK problems, is the long backlog of screening for a variety of medical conditions. There are also people (like myself) who never use loyalty cards. Are they risking their health?