When should unexpected weight loss warrant further investigation to exclude cancer?

### What you need to know Unexpected weight loss presents a diagnostic challenge in primary care. It is associated with a wide range of benign and serious conditions (box 1).1 Box 1 ### Differential diagnosis for patients with unexpected weight loss1RETURN TO TEXT Weight loss may be missed or misattributed because of several factors (see box 2). Once it is detected, the uncertainty for clinicians is not about whether unexpected weight loss is a symptom of concern, it is about who should be investigated further and who can be spared unnecessary investigation. Specifically, how much weight loss, over how much time, in combination with what other clinical features makes cancer sufficiently likely to warrant urgent investigation? Box 2 ### Challenges in detecting weight loss in primary care #### Physiological factorsRETURN TO TEXT