Synopsis
Recognise metastatic malignancy without an identified origin, stabilise urgent complications, perform a focused high-yield diagnostic work-up, and avoid burdensome testing that cannot change treatment or goals.
- Malignancy of undefined primary describes metastatic cancer before a full initial assessment; confirmed cancer of unknown primary remains after appropriate investigation fails to identify origin.
- First confirm malignancy and lineage with adequate tissue; poorly planned broad imaging or tumour markers cannot substitute for pathology.
- History, full examination, basic blood tests and contrast CT chest, abdomen and pelvis form the initial diagnostic core under NICE guidance.
Key red flags
Neurological deficit, obstruction, severe pain, pathological fracture or metabolic deterioration requires emergency treatment before the primary is found.
Investigation priorities
Confirm malignancy, lineage and a plausible organ profile while preserving tissue.
Management branches
The patient has neurological, obstructive, metabolic, haemorrhagic or infective compromise.
- Use ABCDE assessment and activate acute oncology plus the organ-specific emergency team before completing primary-site investigation.
- Obtain the targeted urgent imaging and begin indicated rescue, analgesia and thrombosis or infection management without awaiting every pathology addendum.
Metastatic malignancy is suspected and the patient is stable enough for investigation.