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New research will help GPs to identify the signs, symptoms, and blood test results they should look for to swiftly diagnose cancer in people with unexpected weight loss. The findings have implications for existing health policy and guidelines.

“We know that there is an increased likelihood of a cancer diagnosis within six months of seeing a GP for unexpected weight loss, so it is very important that we identify which patients should be prioritised for cancer investigation.” Said Brian Nicholson, lead author of the research, a practising GP and clinical lecturer at the University of Oxford. “However, there are many non-cancer reasons someone might unexpectedly find their weight dropping, such as recent lifestyle choices and changes, mental ill health, or socioeconomic factors. So, it’s important we priorities the right patients for further investigation.”

Writing in the BMJ, the researchers from the University of Oxford and University of Exeter Medical School examined the patient records of 63,973 adults who visited their GP with unexpected weight loss over a two-year period. They then linked these records with a national cancer registry to work out how many went on to be diagnosed with a cancer and what type.

The researchers looked for additional clinical features in patient records, such as recent blood test results or changes in bowel habit, that might be positive or negative indicators for cancer when combined with unexpected weight loss.

The team found that, of the almost 64,000 people, 908 (1.4%) received a cancer diagnosis within six months of reporting unexpected weight loss. Several symptoms, signs and tests when combined with unexpected weight loss increased the risk of a cancer further and could be used by GPs to identify different cancer types for priority investigation with further tests.

The study highlights where guidelines focussed on investigating individual cancers have the potential to miss other types of cancer. For example, guidelines suggest that patients with unexpected weight loss and abdominal pain should be investigated for colorectal cancer, however, in this study there were over ten additional cancers with these two symptoms that would be missed by colonoscopy.

Professor Willie Hamilton, of the University of Exeter Medical School, a co-author on the study, said: “This study matters in improving cancer diagnosis: we GPs all know weight loss might be cancer. Now we know what other things to ask about, and which cancers to look for. Patients with weight loss have often had several trips to different specialists before their cancer is found – our research should improve this process and detect more cancers at an earlier stage.”

Symptoms that were associated with a cancer diagnosis in patients with unexpected weight loss included abdominal pain, appetite loss, iron deficiency anaemia, jaundice and enlarged lymph nodes. The team were also able to distinguish symptoms that were more important in men, such as difficulties in swallowing (dysphagia) or non-heart related chest pain, and women, such as back pain and indigestion (dyspepsia), that were associated with cancer.

“GPs face a dilemma when faced with a patient who may have cancer but whose symptoms are not enough to justify further investigation immediately and which don’t point to a specific type of cancer,” said Professor Paul Aveyard, practising GP and professor of Behavioural Medicine at the University of Oxford. “This study lets us define some key signs and symptoms to help GP’s home in on the right course of action much quicker – which should improve patient outcomes.”


Prioritising primary care patients with unexpected weight loss for cancer investigation: diagnostic accuracy study 
DOI: 10.1136/bmj.m2651  

Citation: BMJ 2020;370:m2651

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