Diagnostic staging is a mainstay of oncology case management. Staging is the process of determining the extent of local disease and the presence or absence of regional or distant metastasis. A thorough evaluation of the patient begins with a comprehensive physical exam and a minimum database, which includes a complete blood count, chemistry panel, and urinalysis. The scope of the diagnostic workup for staging purposes is dependent upon the known behavior of the individual tumor type combined with the owner’s goals, limitations, and expectations for therapy.
Evaluation of local disease starts with the physical exam to determine the size, appearance, and mobility or fixation of the primary tumor to adjacent tissues. If the neoplasia is internal, imaging via ultrasound, radiographs, computed tomography (CT), or MRI may be necessary for assessment of local extent of disease.
Regional tumor assessment involves evaluation of associated lymph nodes. Documentation of metastases to lymph nodes cannot reliably be made by palpation for size and other physical parameters, but requires cytology or histopathology. Because lymph node drainage can be highly variable, sampling of multiple nodes may be necessary for adequate staging. If a lymph node aspirate is non-diagnostic or if the lymph node cannot be accessed for aspiration, it is a candidate for excisional biopsy. For internal lymph nodes, imaging to assess and potentially guide aspiration is recommended. Imaging techniques useful in the detection of abnormal lymph nodesmay include thoracic radiographs, CT, and abdominal ultrasound.
Distant metastasis refers to spread of cancer beyond regional lymph nodes to distant organs. The presence of confirmed metastases generally implies a worse prognosis and may drastically affect therapeutic decisions. Complete staging can vary depending on the particular tumor type, but distant metastasis may be revealed by a thorough physical examination, abdominal and threeview thoracic radiographs, abdominal ultrasound, nuclear scintigraphy, bone scan, CT, positron emission tomography-CT, or MRI.