Loss Of Weight as predictor of CANcer in primary care (LOWCAN)

AIMS:

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).

METHODS:

• Systematic review: 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 studies: Analyses of two groups of patients will examine the extent to which weight loss indicates cancer in patients presenting to general practice.
• UK cohort: weight loss is recorded as a symptom in the UK national Clinical Practice Research Datalink (CPRD) database. Parralell cohorts of patients with and without weight loss will be followed up to examine the number that turn out to have cancer within 24 months of reporting weight loss.
• US cohort: as weight is not routinely measured at primary care attendance in the UK, 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 (Kaiser Permanente Washington Research Institute).

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.