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Dr Brian Nicholson and colleagues analyse data from primary care to delve into this non-specific cancer symptom.

One ambition of the NHS Long Term plan is that by 2028, 75% of cancers will be diagnosed at stages 1 and 2. General practitioners (GPs) play a key role in this drive for earlier diagnosis by recognising the symptoms of cancer and referring patients exhibiting these symptoms to secondary care diagnostic pathways. In general, each pathway focusses on a relatively narrow range of cancer types, and specific localising symptoms displayed by the patient will influence which cancer pathway they are referred to. However, half of patients with cancer present with non-specific cancer symptoms and wider-ranging investigations are required before the cancer site is determined. This can introduce delays to the diagnosis, which may impact on survival.

Unexplained weight loss is one such non-specific symptom. If more could be understood about the most common cancers associated with unexplained weight loss, and the time to cancer diagnosis, this could inform diagnostic guidelines with the aim of diagnosing these cancers earlier. To achieve this, Brian Nicholson and colleagues from the Nuffield Department of Primary Care Health Sciences and the University of Exeter studied 63,973 patients with unexplained weight loss from the UK’s Clinical Practice Research Datalink (CPRD).

Published in the British Journal of Cancer, the study found that, compared to people without unexpected weight loss, unexpected weight loss was associated with an increased likelihood of pancreatic, gastro-oesophageal, lymphoma, hepatobiliary (liver, gallbladder, biliary tree), lung, bowel and renal tract (renal, bladder) cancers, and cancer of unknown primary. However, this elevated risk was time-limited: 3 months after the initial record of unexpected weight loss, the risk of cancer diagnosis became and remained lower than in those without unexpected weight loss for the rest of the two year study period. This information could help guide the required period of increased vigilance by GPs following presentation of unexplained weight loss if initial investigations do not identify a cancer.

Importantly, following recorded unexpected weight loss, cancers of both early and late-stage were found. One avenue to help diagnose patients displaying non-specific cancer symptoms earlier is through multidisciplinary diagnostic centres, such as the SCAN pathway in Oxfordshire led by Brian Nicholson and Fergus Gleeson (Radiology, Oxford University Hospitals NHS Trust and Department of Oncology). In the SCAN pathway, patients undergo a series of disease site agnostic investigations such as blood and urine tests, and a low dose computed tomography (CT) scan of the thorax, abdomen and pelvis to try to detect the cancer (or other serious condition) responsible for the symptoms.

This study also highlighted that most people with unexplained weight loss don’t have cancer. To avoid unnecessary medical intervention in those with unexpected weight loss but without cancer, future work is needed to identify additional combinatorial risk factors to better discriminate those who warrant further investigation.

Also see the editorial in the British Journal of Cancer on this article.