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.
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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 (T), presence or absence of regional spread to the lymph nodes (N), and metastasis to distant organ sites (M).
PREVENTION AND EARLY DETECTION OF CANCER
You have an essential role in the prevention and early detection of cancer.
As part of your goal related to public education, you need to motivate people to recognize and modify behavior patterns that may negatively impact health, and to encourage awareness and participation in health-promoting behaviors.
DIAGNOSIS of cancer
A diagnostic plan for the person in whom cancer is suspected includes health history, identification of risk factors, physical examination, and specific diagnostic studies (including radiographic and laboratory information).
o Diagnostic studies to be performed will depend on the suspected primary or metastatic site(s) of the cancer.
o Diagnostic studies are used to determine the extent of the disease, tissue of origin, and characteristics that may influence tumor behavior or treatment decisions (e.g., receptor status).
o The biopsy procedure is the only definitive means of diagnosing cancer. Various methods are used to obtain a biopsy depending on the location and size of the suspected tumor.
The goal of cancer treatment is cure, control, or palliation. A number of factors determine the therapeutic approach taken.
o When cure is the goal, treatment is offered that is expected to have the greatest chance of disease eradication and may involve local therapy (i.e., surgery or radiation) alone or in combination with or without periods...