Cancer (medicine)

D

Colorectal Cancer

Colorectal cancer, cancer of the large intestine, is the fourth most common cancer in North America. Many cases of colorectal cancer are associated with low levels of physical activity and with diets that are low in fruits and vegetables. Individuals with a family history of the disease have a higher risk. High rates of colorectal cancer are also found in people who have colorectal polyps, fleshy growths on the inside lining of the large intestine, and in those who have inflammatory bowel disease, a condition causing pain and inflammation of the small intestine or the colon.

Colorectal cancer usually develops slowly and may not produce noticeable symptoms in its early stages. Some individuals with undiagnosed colorectal cancer may detect blood in their feces. They may also experience persistent constipation or diarrhea, abdominal pain, or unexplained weight loss. Eventually the tumor may grow so large that it obstructs the intestine or causes it to rupture. Screening tests can detect precancerous intestinal polyps and colorectal cancer in an early, and easily treatable, stage.

E

Lymphoma

Lymphoma encompasses a group of related cancers that arise in the lymphatic system, organs and cells of the body involved in fighting infection. Lymphomas are classified as non-Hodgkin's lyphoma or as Hodgkin’s disease, a cancer named after British physician Thomas Hodgkin who first described it in 1832. Non-Hodgkins lymphomas generally develop in white blood cells known as lymphocytes that are critical to the functioning of the immune system. Lymphocytes travel throughout the body and thus can spread lymphoma to other organs where they destroy healthy tissue.

The most common symptom of lymphoma is a painless swelling in the lymph nodes in the neck, underarm, or groin. Other symptoms include fevers, night sweats, tiredness, weight loss, itching, and reddened patches on the skin. Sometimes there is nausea, vomiting, or abdominal pain.

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Lymphoma risk increases with age and with decreasing immune function, such as that caused by acquired immunodeficiency syndrome (AIDS) or exposure to certain infectious agents. Organ transplant recipients are at increased risk of lymphoma because they take drugs that weaken the immune system as part of the transplantation process (see Medical Transplantation).

Although the symptoms of Hodgkin’s disease are similar to symptoms of other lymphomas, the cancer cells of the two look different under a microscope, and they grow and spread in different ways. Non-Hodgkin’s lymphoma is more prevalent than Hodgkin’s disease, but Hodgkin’s disease is easier to treat and less severe. The five-year survival rate is more than 80 percent for Hodgkin’s disease and more than the 60 percent for non-Hodgkin’s lymphoma.

F

Bladder Cancer

Bladder cancer affects white Americans at almost twice the rate of African Americans, and men are two to three times more at risk than women. The disease is also more likely to affect smokers than nonsmokers. Occupational exposures also appear to increase risk. People who work in the rubber, leather, and chemical industries are at greater risk, as are hairdressers, machinists, metal workers, printers, painters, and textile workers. Chemicals used in these industries become concentrated in the urine, causing bladder cells to become cancerous.

Bladder tumors may obstruct urine flow into the bladder or interfere with bladder function in other ways. When symptoms are present, they may include blood in the urine and painful or frequent urination. The prognosis is generally excellent when a bladder tumor is detected early.

G

Uterine Cancer

Uterine cancer includes both cervical cancer and endometrial cancer, cancer of the lining of the uterus. The single greatest risk factor for cervical cancer is infection with the human papillomavirus (HPV). The risk increases for women who smoke cigarettes or have many sexual partners. For reasons that are not entirely clear, the disease also seems to be more common in women of low socioeconomic status.

Most cervical cancers develop slowly and may not produce any noticeable symptoms in the early stages. As the cancer progresses, the woman may experience a watery vaginal discharge and painless bleeding. Over time, the bleeding becomes heavier and more frequent, and pain becomes noticeable in the lower abdomen or back. The prognosis for cervical cancer patients in the United States is generally excellent if the cancer is detected early. For unknown reasons, however, black women in the United States are twice as likely to die of the disease as are white women.

The risk of developing endometrial cancer appears to be related to a woman’s exposure to the hormone estrogen. Thus, early onset of menstruation or late menopause increase a woman’s risk, probably by increasing the number of years during which the endometrium is exposed to estrogen. Obesity also increases the risk of endometrial cancer, probably because excess fat can increase estrogen levels in a woman’s body. Tamoxifen, a drug used for preventing breast cancer, acts like estrogen on cells of the endometrium and raises the risk of endometrial cancer.

Endometrial cancer symptoms are similar to those of cervical cancer. Most often, they start with a vaginal discharge that has streaks of blood. The prognosis for endometrial cancer patients is generally excellent if the cancer is caught and treated at an early stage.

H

Skin Cancer

There are three main types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and melanoma. While basal cell and squamous cell carcinomas account for by far the largest percentage of skin cancers, melanoma is the most dangerous type and accounts for almost of the deaths due to skin cancer. The single greatest risk factor is exposure to sunlight, especially during childhood. Melanoma occurs more frequently in people with fair skin and freckles.

Symptoms include any change in the size, shape, color, or texture of a mole or other darkly pigmented area of the skin. Any mole that begins to itch or becomes tender may be a sign of skin cancer. Other signs include sores that do not heal or black spots under a toenail or fingernail that extend beneath the cuticle. Melanoma begins in cells that produce the skin pigment melanin, but it is likely to spread to other parts of the body. Skin cancer is only of the most treatable cancers, with an extremely high survival rate—even for melanoma—if detected early.

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