M Numerical Suffix Assignment
The metastatic status is signified by the letter "M" with subscripts O or 1 to indicate absence or presence of metastatic disease. "M1" signifies presence of metastasis in one or more distant organs.
Common Metastatic Sites
Lung cancer may metastasize to any distant site, the more common being:
Actually, only about 1 percent of patients have complaints related to liver metastasis on initial presentation, but as many as 35 percent of lung cancer patients are found to have hepatic involvement at autopsy. This is usually appreciated clinically as increased liver span and/or nodularity to palpations. Liver enzymes would also be abnormal.
CNS Metastatic Status
The current standard for brain evaluation for mets is as follows. A careful history and detailed neurological is sufficient screen for CNS metastasis. If Hx and Px are negative, we do not have to routinely perform CAT scans of head. Neurologic signs and symptoms of metastases can be quite varied and may be due to other diseases or to systemic manifestations of localized tumors. Additional tests should be undertaken to evaluate these patients.
Bone
Studies have shown that approximately 22% of patients complain of bone pain of initial presentation. However, autopsy studies suggest that only a quarter of patients with bronchogenic carcinoma eventually develop bone metastasis in the course of the disease. The resulting clinical manifestations range from mild pain to pathologic fracture depending on the site, rate of growth, etc. Extension of vertebral metastases may cause epidural compression or vertebral collapse with resulting neurologic complaints. Sciatica has been reported as a presenting complaint, ultimately found to be due to vertebral metastasis. Bone lesions due to lung cancer are far more frequently "lytic" than "blastic."
A rare presentation of skeletal metastasis (monarticular arthritis") is due to involvement of juxta-articular bone or synovial tissue. It presents as inflammation and effusion of the joint. It is most common with the knee, followed by the hip.
Metastasis, distal to the knee or elbow, is rare in any from of cancer. However, at all such metastasis, the primary tumor is almost always found to be bronchogenic. A rare pattern of lytic lesions in the distal phalanges has been identified in cases of lung carcinoma.
Bony involvement in the thorax may take on many clinical pictures depending on location of the pathology. It may occur as direct extension or as bony metastasis which will be addressed shortly. Pain is the most common compliant, with neuralgia, radiculopathy, or even frank paraplegia resulting from vertebral involvement or collapse.
Adrenal Metastatic Status
Review of symptoms or physical exam directed towards evaluation of adrenal glands for metastasis is usually noncontributary. While electrolyte abnormalities secondary to elevated levels of cortisol and ACTH are frequent, they are secondary to a distant manifestation and not due to metastasis. Adrenal insufficiency secondary to metastasis is a rare phenomenon.
CT scan has made it possible for us to evaluate the anatomical features of adrenal gland with ease and accuracy. Bilateral adrenal gland hyperplasia secondary to ACTH production of tumor is a common phenomenon. When masses are seen, CT guided needle aspiration biopsy helps confirm mets, if clinically indicated.