PATIENTS WITH METASTATIC CANCER OF UNKNOWN PRIMARY SITE: DIAGNOSTIC WORKUP AND THERAPEUTIC MANAGEMENT

Metastatic Cancer of Unknown Primary site (CUP) accounts for about 4% of all cancer patients and is therefore one of the 10 most frequent cancer diagnoses in man. It is defined as biopsyconfirmed malignancy for which the site of origin is not identified by routine workup. It is believed that CUP represents a heterogeneous group of malignancies that have a presumably, specific biology with clinical characteristics of rapid progression and random atypical metastases. The diagnostic work-up could be variable. Certain clinicopathological CUP entities are considered as favorable subsets responding to systemic platinum-based chemotherapy or managed by locoregional treatment. These subsets have a better prognosis than the average median survival time of four months in patients who belong to the non-favorable subsets. Introduction and incidence everal terms have been used to describe the condition of unknown primary tumours: these includes: Cancer of Unknown Primary (CUP) site, Unknown Primary Tumours (UPTs), Occult Primary Tumours, Carcinoma of Unknown Primary, Tumour of Unknown (Unidentified) Origin, and Metastases of Unknown (Tumours) Origin. The most widely used terms are the CUP and UPTs 1,2 . CUP is the seventh to eighth most frequently occurring cancer in the world and the fourth commonest cause of cancer death in both males and females 1,3 . The routine workup usually includes a complete history and physical examination, basic laboratory studies, chest x-ray, digital rectal examination and test for stool occult blood. Women should undergo breast and pelvic Correspondence and Requests to Majeed H ALWAN, FRCSEd FACS. 75 A Rotherham Terrace, Miramar, WELLINGTON 6022, NEW ZEALAND E-mail: majeed_h_alwan@yahoo.com Fax: 64-4-388 3442 examination, and men should have a complete prostate and testicular examination. The scenario of CUP poses diagnostic and therapeutic problems, which could cause an unsettling situation to both the patient and relatives from one side and the treating doctor from the other side. It is difficult to determine the appropriate treatment without knowing the primary, because current cancer treatment has been based on the identification of the primary tumour. Also it remains controversial whether the prognosis in CUP improves when the primary tumour is identified by intensive diagnostic search 2 . In 30% of all patients no primary tumour is identified. The primary site becomes obvious in only 25% of patients during their lifetime. The primary lesion can be identified in only 30% to 82% of cases at autopsy 4 . The most common sites of origin are the lung (30%) and the pancreas (20%). Furthermore, primary tumours are S