Loss Of Weight as a predictor of CANcer in primary care (LOWCAN)
The overall aim is to provide the evidence necessary to allow GPs to more effectively implement the NICE cancer guidance on the management of unexplained weight loss.
Why this is important:
Existing research suggests that weight loss is a "low-risk, but not no-risk" symptom, estimating that between 1 in 200 and 1 in 30 patients with unexplained weight loss go on to develop cancer.
However, it is not clear how "weight loss" should be interpreted by general practitioners - how much weight loss is important and over what time-period? Should they routinely measure and monitor patients weight or wait for the symptom to be volunteered? And is its diagnostic value independent of other symptoms? It is also unclear whether weight loss is a useful symptom for diagnosing cancer at an early and potentially curable stage.
Without clarification of these points, GPs may adopt too high a risk threshold for referral (choosing to watch and wait inappropriately and potentially missing cancer cases) or too low a threshold (overburdening resources in secondary care and exposing patients to unnecessary investigation).
- Systematic review: We will conduct a systematic literature review to identify, assess the quality of, and synthesise all the previous research on the diagnostic value of weight loss as an indication of cancer.
- Core research study: The core study involves new analysis of two groups of patients to examine the extent to which weight loss indicates cancer in patients presenting to general practice .Weight loss is recorded as a symptom in the UK national Clinical Practice Research Datalink (CPRD) database (which covers 15 million patients and is linked to cancer data). It will be analysed using a cohort approach - patients with and without weight loss will be followed up in the database to examine the number that turn out to have cancer within 18 months of reporting weight loss. However, weight is not routinely measured at primary care attendance in the UK and so to discover the diagnostic value of measured weight loss (rather weight loss as a symptom reported by patients) it is necessary to use data from another country. A similar analysis will be carried out on a primary care database from the US (Group Health).
- Feasibility study: The feasibility study will enable further work if it reveals that weight loss is important but existing data is inadequate to answer all of the questions. Dr Brian Nicholson will work with primary care software developers and a scale manufacturer to create a system that can automatically put patients' weights into the medical record and test how feasible and acceptable this is to staff and patients in 5 general practices. In principle, this is acceptable to patients in cultures similar to our own, e.g. the US, but issues of system, workload and priority will dominate whether it will work in the UK.
How could this benefit patients?
By substantially strengthening the evidence base underpinning the current NICE guidelines, and thereby providing clearer and more pragmatic advice to GPs on the investigation and referral of patients with unexpected weight loss, it is hoped that the diagnostic delay which characterises cancer diagnosis in UK primary care will be reduced.