Ch 16 Essay

2516 Words Apr 25th, 2015 11 Pages

Biology of Cancer Cancer encompasses a broad range of diseases of multiple causes that can arise in any cell of the body capable of evading regulatory controls of proliferation and differentiation. Two major dysfunctions present in the process of cancer are (1) defective cell proliferation (growth) and (2) defective cell differentiation. Cancer cells usually proliferate at the same rate of the normal cells of the tissue from which they arise. However, cancer cells divide indiscriminately and haphazardly and sometimes produce more than two cells at the time of mitosis. Through differentiation, cells become capable of performing only specific functions. o Proto-oncogenes are normal cell genes that regulate
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Cancer cells may display altered cell surface antigens, called tumor-associated antigens, as a result of malignant transformation. Immunologic surveillance is the response of the immune system to these antigens. The process by which cancer cells evade the immune system is termed immunologic escape. Oncofetal antigens are a type of tumor antigen that can be used as tumor markers that may be clinically useful to monitor the effect of therapy and indicate tumor recurrence.

Classification of Cancer Tumors can be classified according to anatomic site, histologic grading, and extent of disease (staging). In the anatomic classification of tumors, the tumor is identified by the tissue of origin, the anatomic site, and the behavior of the tumor (i.e., benign or malignant). In histologic grading of tumors, the appearance of cells and the degree of differentiation are evaluated pathologically. For many tumor types, four grades are used to evaluate abnormal cells based on the degree to which the cells resemble the tissue of origin. The staging classification system is based on a description of the extent of the disease rather than on cell appearance. Assignment is completed after the diagnostic workup and determines treatment options. o The clinical staging classification system uses five stages, from in situ to metastasis. o The TNM classification system uses three parameters: tumor size and invasiveness

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