Biopsy

 A cancer may be suspected for a variety of reasons, but the definitive diagnosis of most cancers must be confirmed by histological examination of the cancerous cells by a pathologist. Tissue can be obtained from a biopsy or surgery. Many biopsies (such as those of the skin, breast or liver) can be done in a doctor's office. Biopsies of other organs are performed under anesthesia and require surgery in an operating room.

 The tissue diagnosis indicates the type of cell that is proliferating, its histological grade and other features of the tumor. Together, this information is useful to evaluate the prognosis of this patient and choose the best treatment. Cytogenetics and immunohistochemistry may present information about future behavior of the cancer (prognosis) and best treatment.