– A cellular malignancy in which the affected cell displays unregulated growth and division and lack of differentiation as it invades adjacent tissues and proliferates. The altered cells, which form solid or diffuse tumors, are classified by the tissue from which they arise and are described according to a histogenetic system.
Causes and Incidence
The transformation of normal cells into cancer cells (carcinogenesis) appears to be a multistep process involving many factors. Thus far, no single theory of causation has satisfactorily explained this process. Causative agents have been identified for some forms of cancer, and others are being investigated. Cancer is the second leading cause of death in the United States. Each year, more than 525,000 people die of cancer and 1.17 million new cases are diagnosed. Although various forms of cancer strike various societal subgroups, cancer is a universal disease seen across cultural, racial, gender, age, and socioeconomic groups.
Cancer occurs when certain cells proliferate without organization and with little or no differentiation. It has been theorized that certain stimuli, as yet to be definitively identified, initiate this proliferation by overpowering the normal mechanisms controlling growth. The result is uninhibited growth, uncontrolled function, and rapid motility, permitting spread of the cancerous cells to other parts of the body through invasion of adjacent tissue or migration via the blood or lymph system. The migration process is commonly called metastasis. The primary site of a malignancy (cancer cell growth) is the site of original growth; a secondary site is created when cells migrate to and colonize an additional body site.
The American Cancer Society lists seven warning signs of cancer that require immediate attention from a physician: (1) a change in bowel or bladder habits; (2) a sore that does not heal; (3) unusual bleeding or discharge; (4) a thickening or lump in the breast or elsewhere; (5) indigestion or difficulty swallowing; (6) an obvious change in a wart or mole; and (7) a nagging cough or hoarseness.
The prognosis generally declines as the disease stage advances (with evidence of lymph node involvement or metastasis). If the condition goes untreated, the cancer cells continue to proliferate, and eventually death results. Cardiac tamponade, pleural effusion, and paraneoplastic syndromes, which are all complications that can occur with various malignancies, are oncologic emergencies.
Cancer screening is an important tool in the early detection and diagnosis of cancer. The following chart summarizes the American Cancer Society’s screening recommendations for asymptomatic individuals of average risk.
Stool blood test
Digital rectal examination
Prostate examination and prostatespecific antigen test
Pap smear and pelvic examination
Sexually active or by age 18
Endometrial tissue sample
Menopause or high-risk individual*
Clinical breast examination
Every 3 years Annually
1-2 years Annually
Health counseling and cancer check-up ;
Every 3 years Annually
*History of infertility, obesity, failure to ovulate, abnormal uterine bleeding, or estrogen therapy.
Counseling on use of tobacco, sun exposure, diet, risk factors, sexual practices, and environmental and occupational exposures.
If screening techniques and the clinical examination indicate the possibility of cancer, a definitive diagnosis is made through histopathologic examination of tissue obtained by aspiration cytologic techniques or by excisional, endoscopic, or bone marrow biopsy. If an unequivocal diagnosis is made, staging is done for prognostic information and to guide treatment decisions. A comprehensive system known as the TNM system was developed. It involves assessment of three basic components: the size of the primary tumor (T); whether regional lymph nodes (N) are involved; and whether distant metastases (M) are present.
Removal of primary tumor with or without lymph nodes and adjacent structures; palliative procedures to relieve symptoms.
Chemotherapeutic agents, hormones to reduce size of tumor and induce remission; immunotherapy or biologic response modifiers to strengthen immune function.
Radiation therapy to reduce size of tumor and check metastasis; bone marrow transplant.