![]() Understanding the enigma of cancer cell spread to distant sites, which accounts for over 90% of cancer-related deaths, necessitates comprehensive investigation. Some new hypotheses were suggested as well, i.e., under the effect of particular biochemical and/or physical stressors, cancer cells can undergo nuclear expulsion with subsequent macrophage engulfment and fusion, with the formation of cancer fusion cells (CFCs). Ĭurrently, three main theories have been proposed to explain the metastatic pathway of cancer: the epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) hypothesis (1), the cancer stem cell hypothesis (2), and the macrophage–cancer cell fusion hybrid hypothesis (3). The most common sites of metastases are the lungs, liver, brain, and the bones. The spread of metastasis may occur via the blood or the lymphatics or through both routes. Metastatic tumors are very common in the late stages of cancer. When the organ gets a metastatic disease it begins to shrink until its lymph nodes burst, or undergo lysis. Some patients, however, do not show any symptoms. Brain metastasis: neurological symptoms such as headaches, seizures, and vertigo Īlthough advanced cancer may cause pain, it is often not the first symptom.Bone metastasis: bone pain, fracture of affected bones.Liver metastasis: hepatomegaly (enlarged liver), nausea and jaundice.Lung metastasis: cough, hemoptysis and dyspnea (shortness of breath).In lymph node metastasis, a common symptom is lymphadenopathy.The lungs, liver, brain, and bones are the most common metastasis locations from solid tumors. Initially, nearby lymph nodes are struck early. Signs and symptoms Cut surface of a liver showing multiple paler metastatic nodules originating from pancreatic cancer The possibilities of curative treatment are greatly reduced, or often entirely removed when a cancer has metastasized. In overall stage grouping, metastasis places a cancer in Stage IV. ![]() Metastasis is a key element in cancer staging systems such as the TNM staging system, where it represents the "M". The tumor in the lung is then called metastatic breast cancer, not lung cancer. This means that if breast cancer metastasizes to the lungs, the secondary tumor is made up of abnormal breast cells, not of abnormal lung cells. When tumor cells metastasize, the new tumor is called a secondary or metastatic tumor, and its cells are similar to those in the original or primary tumor. Basal cell carcinoma for example rarely metastasizes. Most cancers can metastasize, although in varying degrees. Metastasis is one of the hallmarks of cancer, distinguishing it from benign tumors. This new tumor is known as a metastatic (or secondary) tumor. After the tumor cells come to rest at another site, they re-penetrate the vessel or walls and continue to multiply, eventually forming another clinically detectable tumor. This process is known (respectively) as lymphatic or hematogenous spread. Some cancer cells known as circulating tumor cells acquire the ability to penetrate the walls of lymphatic or blood vessels, after which they are able to circulate through the bloodstream to other sites and tissues in the body. This malignancy allows for invasion into the circulation, followed by invasion to a second site for tumorigenesis. The cells which constitute the tumor eventually undergo metaplasia, followed by dysplasia then anaplasia, resulting in a malignant phenotype. This uncontrolled proliferation by mitosis produces a primary heterogeneic tumour. Ĭancer occurs after cells are genetically altered to proliferate rapidly and indefinitely. It is generally distinguished from cancer invasion, which is the direct extension and penetration by cancer cells into neighboring tissues. The newly pathological sites, then, are metastases ( mets). Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body the term is typically used when referring to metastasis by a cancerous tumor. Metastasis /mᵻˈtastəsɪs/ metastases / m ə ˈ t æ s t ə s iː z/.
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