Surgery

 In theory, cancers can be cured if entirely removed by surgery, but this is not always possible. When the cancer has metastasized to other sites in the body prior to surgery, complete surgical excision is usually impossible.

 Examples of surgical procedures for cancer include mastectomy for breast cancer. The goal of the surgery can be either the removal of only the tumor, or the entire organ. A single cancer cell is invisible to the naked eye but can regrow into a new tumor, a process called recurrence. For this reason, the pathologist will examine the surgical specimen to determine if a margin of healthy tissue is present, thus decreasing the chance that microscopic cancer cells are left in the patient.

 In addition to removal of the primary tumor, surgery is often necessary for determining the extent of the disease and whether it has metastasized to regional lymph nodes. This is a major determinant of prognosis and in establishing the adjuvant therapy.

 Occasionally, surgery is necessary to control symptoms, such as spinal cord compression or bowel obstruction. This is referred to as palliative treatment.