This is a european randomised, phase III, multi-centric study comparing a diagnostic and therapeutic strategy based on molecular analysis followed by suspected primary cancer tailored specific therapy, to an empiric strategy in patients with carcinoma of unknown primary. The purpose of this trial is to determine whether or not a strategy based on molecular analysis is effective in improving the progression free survival rates of patients with carcinoma of unknown primary (CUP).

Inclusion Criteria:

1. Patients presenting with carcinoma of unknown primary, confirmed by histopathological analysis (including an immunohistochemical analysis) and corresponding to one of the following histologic types : moderately or well-differentiated adenocarcinoma, poorly-differentiated adenocarcinoma, undifferentiated carcinoma, squamous-cell carcinoma
2. Diagnostic work-up in keeping with Standard Options Recommandations des CAPI (Lesimple et al., 2003),
3. Age > 18 years,
4. Performance Status 0, 1 or 2 according to ECOG
5. Good or poor prognosis CUP classified according to the GEFCAPI classification
6. CUP with at least one measurable lesion
7. Tumour sample available for molecular analysis
8. CUP not belonging to a subgroup requiring a specific treatment,
9. Satisfactory haematological, renal and hepatic function
10. Cardiac, respiratory and neurological function compatible with the administration of cisplatin chemotherapy,
11. No previous chemotherapy for a CUP
12. Previous radiotherapy is acceptable, but it should be completed at least 4 weeks before the start of systemic treatment. Randomization can be performed during this time frame.
13. All patients with reproductive potential must practice an effective method of birth control throughout the study. Female patients with childbearing potential must have a negative pregnancy test within 7 days before study treatment
14. Information delivered to patient and informed consent form signed by the patient or legal representative.

Exclusion Criteria:

1. Patients in whom the diagnosis has not been histologically confirmed (a cytological analysis alone does not permit patient entry onto the trial),
2. Patients with known HIV infection
3. Patients with symptomatic brain metastases,
4. Associated disease likely to prevent the patient from receiving the treatment,
5. Previous history of cancer (excepted skin basocellular epithelioma or epithelioma in situ of the uterine cervix) during the 5 years before study entry,
6. Patients already included in another clinical trial with an experimental therapy,
7. Pregnant woman or woman who are breastfeeding,
8. Compliance with trial medical follow-up impossible due to geographic, social or psychological reasons.