Sporadic Cancers

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Of all cancers, 90% to 95% are sporadic. In other words, even though all cancers are caused by damage to genetic information, most cancers are not passed on from parent to child. Sporadic cancers develop as people acquire mutations in proto-oncogenes, tumor suppressor genes, and DNA repair genes. These mutations either occur in somatic cells or in germline cells that are not involved in fertilization; therefore, the mutations are not passed on to the next generation. Acquired mutations accumulate over a person's lifetime. They are usually caused by chance events, including exposures to a variety of genetically damaging agents or as a result of errors in DNA replication prior to cell division.

Clinical Example: Todd is a 53-year-old Caucasian male. He is married and has 2 daughters and a son. Todd grew up on the coast of Florida. As a child, he enjoyed many outdoor activities including swimming, canoeing, and fishing. Todd continued to enjoy the warm, sunny climate in Florida as a teenager and young adult. Although Todd has fair skin and freckles, he always liked to maintain as much of a tan as possible and didn't often use sunblock. Recently, Todd noticed a new and unusual-looking mole on his arm, so he made an appointment with his family doctor. The mole looked suspicious to the physician, so he removed it and forwarded a sample to the laboratory for diagnosis. Shortly thereafter, Todd was diagnosed with basal cell carcinoma (the most common form of skin cancer) and was successfully treated. He now uses sunblock and protective clothing when outdoors. Todd's skin cancer was the result of sun damage. It was not a form of skin cancer that is considered to be part of a hereditary skin cancer syndrome.