hematology and oncology
Cancer Diagnosis
Staging
Once a histologic diagnosis is made, staging (ie, determination of the extent of disease) helps in treatment decision-making and influences prognosis. Clinical staging uses data from the history, physical examination, imaging tests, laboratory tests, and biopsy of bone marrow, lymph nodes, or other sites of suspected disease. For staging of specific neoplasms, see details in the organ-relevant discussion. Imaging tests, especially CT, PET, and MRI, can detect metastases to brain, lungs, or abdomen, including the adrenal glands, retroperitoneal lymph nodes, liver, and spleen. MRI (with gadolinium contrast) is the procedure of choice for recognition and evaluation of brain cancers, primary and metastatic. PET scanning is increasingly being used to determine the metabolic activity of a suspect lymph node, lung nodule, or other mass. Integrated PET–CT can be valuable, especially in lung, head and neck, and breast cancer and in lymphoma. Ultrasonography can be used to study breast, ovarian, orbital, thyroid, cardiac, pericardial, hepatic, pancreatic, renal, testicular, and retroperitoneal masses. It may help guide percutaneous biopsies and differentiate fluid-filled cysts from solid masses. Nuclear scans can identify several types of metastases (eg, thyroid cancer). Bone scans identify abnormal bonegrowth(ie, osteoblastic activity) before it is visible on plain x-ray. Thus, bone scans are useless in neoplasms that are purely lytic (eg, multiple myeloma); routine bone x-rays are the study of choice in such diseases. Serum chemistry and enzyme measurements may help staging. Elevated liver enzyme (alkaline phosphatase, lactate dehydrogenase, alanine aminotransferase) levels and elevated bilirubin levels suggest liver metastases. Elevated serum alkaline phosphatase and calcium may be the first evidence of bone metastases. Elevated bloodureanitrogen or creatinine levels may indicate cancer involvement of the kidney, collecting system, or bladder. Elevated uric acid levels often occur in patients with rapidly proliferating cancers and in those with myeloproliferative and lymphoproliferative disorders. However, most people with an increased uric acid level do not have cancer. Mediastinoscopy and Mediastinotomy is especially valuable in the staging of non–small cell lung cancer. When mediastinal lymph node involvement is found, patients may benefit from pre-surgery chemotherapy and/or radiation therapy. Bone marrow aspiration and biopsy are especially useful in detecting involvement by leukemias, lymphomas, and plasma cell myeloma (multiple myeloma) and metastases from small cell lung, breast, and prostate cancers. Bone marrow biopsy may be informative in patients with unexplained hematologic abnormalities (ie, anemia, thrombocytopenia, pancytopenia). Biopsy of sentinel regional lymph nodes is part of the evaluation of many cancers, such as breast, thyroid, gastric, lung, and colon cancers and melanoma. Removal of a sentinel lymph node (as defined by uptake of contrast or radioactivity injected into the cancer) may allow limited but definitive lymph node sampling in patients with these cancers. 