What are purposes of biopsy of metastatic tumors?

➢ Histological diagnosis of the lesion (lymphoma? Sarcoma? Adenocarcinoma? ...); ➢ Orientation towards a primary neoplasia when it is not known or found; ➢ Possible identification of therapeutic targets (RH, HER-2, search for molecular anomalies predictive of response or non-response to socalled "targeted" treatments). ➢ Histological evidence (diagnostic certainty) is necessary because: ✓ Treatments are potentially toxic; ✓ Treatments depend on histological types and primary cancer; ✓ Some treatments are "targeted" In about 10% of cases primitive neoplasm is not found : They are generally so-called “metastasis from unknown primary” adenocarcinomas and they have a poor prognosis