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Neoplasia is a disease process that results in over 100 different
malignant diseases that share a common biology and natural history.
Any cell in the body that can undergo mitosis or cell division can
be affected. Cancer has links to other disease processes. Some
infections cause cancer: e.g. schistosomiasis associated with
bladder cancer and the liver fluke, Clonorchis sinensis, which
causes cancer of the gall bladder. There are also toxic causes:
e.g. mesothelioma, a tumor arising in the pleura which lines the
thoracic cavity resulting from exposure to asbestos (asbestosis).
Despite popular opinion, however, it is unlikely that local trauma
is a cause of cancer.
As a fundamental disorder of cellular growth and
differentiation or development, cancer is essentially a genetic
disorder at the cellular level. Most tumors are encapsulated and
benign in behavior. Occasionally they may create symptoms from
cosmetic or mass effects. In using the generic word “cancer”,
however, we are concerned here with malignant tumors that are
morphologically abnormal under the microscope. They show
uncontrolled growth leading to local invasion with disruption of
tissues, and later metastasis or spread to loco-regional lymphatics
and later the blood stream. Cancer kills mostly through blood-borne
metastasis.
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