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'Tumor' or 'tumour' (via Old French ''tumour'' from Latin ''tumor'' "swelling") is an abnormal growth or mass of tissue. A tumor can be either malignant or benign. Nearly all tumors are examples of neoplasia, although certain developmental malformations or inflammatory masses may occasionally be referred to as tumors.

Contents

Causes

See also

References

Causes

Neoplastic tumors are caused by mutations in DNA of cells, which interfere with a cell's ability to regulate and limit cell division. An accumulation of mutations is needed for a tumor to emerge. Mutations that activate oncogenes or repress tumor suppressor genes can eventually lead to tumors. Cells have mechanisms that repair DNA and other mechanisms that cause the cell to destroy itself by apoptosis if DNA damage gets too severe. Mutations that repress the genes for these mechanisms can also eventually lead to cancer. A mutation in one oncogene or one tumor repressor gene is usually not enough for a tumor to occur. A combination of a number of mutations is necessary.
More recently, it has emerged that some human cancers, particularly epithelial cancers, are caused by virus infection. One common group of cancer-causing viruses are members of the Herpesvirus family, which can cause cancers such as Kaposi Sarcoma. A recent vaccine for the causative agent of many forms of genital warts, human papillomavirus (HPV), was publicised as a vaccine against cervical cancer, as HPV causes nearly all primary cervical cancers.
DNA microarrays can be used to determine if the expression of oncogenes or tumor repressor genes has been altered. Possibly in the future tumors can be treated better by using DNA microarrays to determine the exact characteristics of the tumor.

See also

★ Tumor antigen

★ Tumor marker

References

★ Robbins Pathologic Basis of Disease, Sixth Edition, Ramzi Cotran, Vinay Kumar, Tucker Collins, , , W.B. Saunders, 1999,