Surgery is used to diagnose cancer, determine its stage, and to treat cancer. One common type of surgery that may be used to help with diagnosing cancer is a biopsy. A biopsy involves taking a tissue sample from the suspected cancer for examination by a specialist in a laboratory. A biopsy is often performed in the physician’s office or in an outpatient surgery center. A positive biopsy indicates the presence of cancer; a negative biopsy may indicate that no cancer is present in the sample.