These examples are used to illustrate some general aspects of cancer. Additional details are provided in the appropriate chapter dealing with the affected system.
1. Skin Cancer
Skin cancer is visible, easily diagnosed, and treated (by surgery), and develops slowly; therefore most types have an excellent prognosis. Skin cancers have the highest rate of recurrence and usually arise on the head and neck or back, areas exposed to the sun and irritation. They occur more frequently in individuals with fair skin who are over 40 years of age and live in southern climates. The number of cases is increasing, resulting in a public education campaign to reduce sun exposure and tanning practices.
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Basal cell carcinoma is the most common form of skin cancer. The tumor appears as a pearly papule and develops central ulceration, a "rodent ulcer". Significant characteristics of the lesion include lack of pain or pruritus (itching) and persistence-the lesion remains and grows slowly. The tumor is slowly invasive.
2. Ovarian Cancer
Ovarian cancer has a very poor prognosis, ranking high in mortality rates. The tumor is hidden in the peritoneal cavity; it is a "silent" tumor. Although there are many histologic types of ovarian cancer, this section deals only with the basic concepts. Hormonal and genetic factors appear to play a role in the development of this cancer.
Presenting (or first) signs are vague and appear only when the tumor is well advanced and is large enough to cause pressure on the adjacent structures, such as the bladder or the intestine, or when an inflammatory exudate forms in the abdominal cavity. There are no definite tumor markers to assist in early diagnosis. The marker CA125 is elevated in other conditions as well as ovarian cancer but is useful in monitoring the effectiveness of treatment. The first indications are usually altered bowel or bladder function or increased abdominal girth. The tumor spreads easily by means of the lymphatic vessels and by seeding as cancer cells pass along the peritoneal membranes or are sloughed into peritoneal fluid, traveling to the liver and other organs, cancer also invades the uterus and pelvis. Treatment includes surgery, radiation, and chemotherapy.
3. Brain Tumors
Brain tumors may be benign or malignant. Both are space-occupying masses that create pressure inside the skull, and both are serious for this reason. Brain tumors, even when small, can cause death if they are located in the brainstem or cerebellum where they can interfere with vital functions such as respiration. Removal of the mass may be fairly easy if it is located on the brain surface but difficult and dangerous if it is located elsewhere. Brain tumors vary histologically, originating from neurons, neuroglia cells, blood vessels, or connective tissue. They can occur in children as well as adults. Early indications of brain tumors are seizures or signs of pressure such as headache, drowsiness, vomiting, visual problems, or impaired motor function. Malignant brain tumors do not metastasize outside the central nervous system. However, tumors from the breast or lung or bone can metastasize into the brain, forming secondary tumors. Treatment may be surgery, radiation, or chemotherapy and may cause the loss of some additional brain tissue.
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4. BREAST CANCER
W.R., a 32-year-old woman, felt a small, hard, painless lump in her left breast during regular self-examination. The lump did not disappear during the next few days, so she went to her physician for an examination. Tests followed, and a biopsy confirmed the presence of a malignant tumor. The tumor (1.5 cm) was removed, as well as five lymph nodes, two of which contained malignant cells. No other metastases appeared to be present. Courses of radiation and chemotherapy were recommended following a 6-week recovery period, and the prognosis appeared good.
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