Cancer (medical term: malignant neoplasm) is a group of diseases in which a group of cells display the traits of uncontrolled growth (growth and division beyond the normal limits), invasion (intrusion on and destruction of adjacent tissues), and sometimes metastasis (spread to other locations in the body via lymph or blood). These three malignant properties of cancers distinguish them from benign tumors, which are self-limited, do not invade or metastasize. Mainly cancers form a tumor but some, like leukemia, do not.
Almost all cancers are caused by abnormalities in the genetic material of the transformed cells. These abnormalities may be cause due to the effects of carcinogens, such as tobacco smoke, radiation, chemicals, or infectious agents. Other cancer-promoting genetic abnormalities may be accidentally acquired through errors in DNA replication, or are inherited, and thus present in all cells from birth. Complex interactions between carcinogens and the host genome may clarify why only some develop cancer after exposure to a known carcinogen. New aspects of the genetics of cancer pathogenesis, such as DNA methylation, and microRNAs are gradually more being recognized as important.
Almost all cancers are caused by abnormalities in the genetic material of the transformed cells. These abnormalities may be cause due to the effects of carcinogens, such as tobacco smoke, radiation, chemicals, or infectious agents. Other cancer-promoting genetic abnormalities may be accidentally acquired through errors in DNA replication, or are inherited, and thus present in all cells from birth. Complex interactions between carcinogens and the host genome may clarify why only some develop cancer after exposure to a known carcinogen. New aspects of the genetics of cancer pathogenesis, such as DNA methylation, and microRNAs are gradually more being recognized as important.
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