Metastatic Cancer of Unknown Primary

Cancer Care Alberta

Cancer of unknown primary (CUP) is a heterogeneous group of tumours that present initially with metastasis, and in which a properly standardized diagnostic work-up cannot identify the original site of the malignancy. CUP accounts for:

• 2-9% of cancer diagnoses
• is the 8th most frequent cancer diagnosis
• occurs most commonly between the ages of 60 and 75 years

A review of 884 patients reported the most common underlying occult primary tumours are of lung, pancreas, and hepatobiliary tree origin.

Prognosis is favourable (15-20% of cases) where tumours are:

• chemosensitive
• poorly differentiated midline carcinomas
• peritoneal papillary adenocarcinomas in women
• metastatic adenocarcinoma involving the axillary lymph nodes only
• metastatic squamous cell carcinoma in the cervical lymph nodes
• single-node metastases
• poorly differentiated neuroendocrine carcinoma
• resectable tumours
• germ cell tumours

Prognosis is poor (a median survival approximately 4 month) where patients have:

• impaired performance status
• elevated serum LDH level

The initial clinical assessment of patients should be directed at identifying the extent of the disease and tumour subtypes in which a specific therapy may improve the patient’s symptoms and prognosis.

The following resources are available to help you navigate potential concerns around cancer suspicion, diagnosis, referral pathways and other important information.

ON THIS PAGE:
Quick Reference|Referrals|Patient Resources