Tumor progression involves three stages: hyperplasia, dysplasia, and carcinoma. Mutations in oncogenes and tumor suppressor genes can cause cancer to metastasize, leading to more advanced stages. Different factors determine the stage of cancer, including tumor size, location, and lymph node involvement.
Tumor progression refers to the steps and stages a cancerous tumor goes through as it grows or spreads. The development of a single tumor generally includes three stages: hyperplasia, dysplasia, and carcinoma. Overall cancer progression with malignancies can also undergo four or more separate stages as the cancer metastasizes to other areas of the body.
Abnormal cell growth fuels single tumor progression, and single cell alteration sets the stage for hyperplasia. The causes of the genetic alteration of the cell of origin are often unknown. During hyperplasia, the cell continues to divide uncontrollably, producing an overabundance of itself. These cells have reached the stage of dysplasia when they begin to undergo structural changes that give them an unusual, bumpy appearance. Once the cells cover a large contained area and succumb to functional changes that render them useless in their original functions, carcinoma has occurred.
A carcinoma in situ represents a single tumor. Tumors often appear as hard, firm masses due to the disorganized nature of the cells. They can occur in almost any cell in the body and therefore tumors can be found on any organ. Cancers that occur in the blood or on the skin may take on a different or not clearly visible abnormal appearance. Any malignant tumor can begin the process of metastasis.
Metastasis facilitates tumor progression to other previously unaffected areas of the body. Mutations in two types of genes usually create the conditions for tumor progression: oncogenes and tumor suppressors. Oncogenes are the substances in the body responsible for cell division and cell movement. Sometimes, a change in these genes can cause them to exert too much influence, subsequently causing both rapid cell growth and high protein concentration. At the same time, the mutations can inactivate tumor suppressor genes. These genes are the security guards that stop abnormal cell division; if they are neutralized, the oncogenes carry out their destructive behaviors out of control.
Cancer progression is often divided into stages that characterize the promotion or progression of the initial tumor and the degree of metastasis. In addition to the aforementioned cellular composition of the cells and the manifestation of the spread, other factors that determine the stage of a cancer include the size of the tumor, the location of the tumor and the particular role of the lymph nodes in the cancer. Different staging systems are used, but one well-known system divides cancer and tumor progression into four stages. More advanced stage three or four cancers generally include larger tumors and cancer cells that have reached the lymph nodes. In more severe late-stage tumors, metastases to surrounding organs have also occurred.
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