A scoping review of unexpected weight loss and cancer: risk, guidelines, and recommendations for follow-up in primary care.

Background: Cancer diagnoses often begin with consultations with general practitioners (GPs), but the nonspecific nature of symptoms can lead to delayed diagnosis. Unexpected weight loss (UWL) is a common nonspecific symptom linked to undiagnosed cancer, yet guidelines for its diagnostic assessment in general practice lack consistency.

Aim: To synthesise evidence on the association between UWL and cancer diagnosis, and to review clinical guidelines and recommendations for assessing patients with UWL.

Design and settings: Systematic search and analysis of studies conducted in primary care.

Method: Four databases searched for peer-reviewed literature from 2012 to 2023. Two reviewers conducted all the steps. A narrative review was conducted detailing the evidence for UWL as a risk factor for undiagnosed cancer, existing clinical guidance, and recommended diagnostic approach.

Results: We included 25 studies involving 916,092 patients; 92% provided strong evidence of an association between UWL and undiagnosed cancer. The National Institute for Health Care and Excellence Cancer Guideline in the UK was frequently cited. General suggestions encompassed regular weight monitoring, family history, risk factor evaluation, additional signs and symptoms, and a comprehensive physical examination. Commonly recommended pathology tests included C-reactive protein, complete blood count, alkaline phosphatase, and thyroid-stimulating hormone. Immunochemical faecal occult blood test, abdominal ultrasound, and chest X-ray were also prevalent. One large cohort study provided age, sex, and differential diagnosis-specific recommendations.

Conclusion: This evidence review informs recommendations for investigating patients with UWL and will contribute to a computer decision support tool implementation in primary care, enhancing UWL assessment and potentially facilitating earlier cancer diagnosis.