Trial Comparing Cisplatin With or Without Gemcitabine in Patients With Carcinoma of Unknown Primary

Inclusion Criteria: * Patients older than 18 years * Evidence of CUP based on histologic examination * Negative search for the primary tumor site using recommended guidelines * Disease classified as good prognosis according to the French classification criteria: \*performance status \>2 and \*normal serum LDH * No prior chemotherapy * No previous carcinoma, except basal-cell carcinoma of the skin * Adequate renal function: measured or calculated creatinine clearance \> 60 ml/min * Absolute granulocyte count ≥ 1,500/mm3; platelets ≥ 100,000 mm3; bilirubin ≤ 1.5 fold the upper normal value * Signed informed consent Exclusion Criteria: * Patients infected by the Human Immunodeficiency Virus (HIV) * CUP belonging to one of the following subgroups: 1) Axillary lymph node of an adenocarcinoma in a woman; 2) Serous adenocarcinoma of the peritoneum in a woman; 3) Undifferentiated carcinoma of the middle line in a young man; 4)Squamous-cell carcinoma; 5) Neuroendocrine carcinoma; 6) Bone metastases with elevated serum prostate specific antigen (PSA) in a man * Patients who do not fit inclusion criteria.