Understanding Cancer

The term cancer comes from the Latin word meaning crab. Cancer was characterized as a crablike disease by the Greek physician Hippocrates, who observed that cancers spread throughout the body, eventually cutting off life. Now cancer generally is defined as the unregulated growth of specific cells in the body. The word cancer actually refers to over 100 different diseases, but in all cases, certain body cells multiply in an abnormal, unregulated manner.

Normally, the growth and reproduction of every cell in the body are regulated. This regulation, in turn, determines the size and functions of tissues and organs. If a normal body cell begins to grow abnormally and reproduces too rapidly, a mass of abnormal cells eventually develops called a tumor. A tumor generally contains millions of genetically identical abnormal cells before it can be detected or felt.

Types of Tumors

If the cells of the tumor remain localized at the site of origin in the body and if they multiply relatively slowly, the tumor is said to be benign. Benign tumors, such as cysts, warts, moles, and polyps, do not spread to other parts of the body. Benign tumors usually can be removed surgically and generally are not a threat to life. In fact, benign tumors weighing several hundred pounds have been surgically removed from persons who then recovered fully. Benign tumors cannot re-grow if all of the abnormal cells are removed by surgical excision of the tumor.

Malignant tumors are composed of cells that grow rapidly, have other abnormal properties that distinguish them from normal cells, and invade other normal tissues. In particular, malignant cells may have altered shapes and cell-surface characteristics that contribute to their rapid proliferation. Many malignant cells also have abnormal chromosomes or altered genes, and they manufacture abnormal proteins. The numerous altered properties of malignant cells enable a pathologist, who is a physician who specializes in the causes of diseases, to determine whether the cells removed from a tumor are abnormal and to what degree.

What is Metastasis?

The cells of most malignant tumors also may undergo metastasis, a process in which cells detach from the original tumor, enter the lymphatic system and bloodstream, and are carried to other organs. Once the malignant cells spread to other organs, they develop into new tumors that often grow more rapidly than cells in the original tumor. Metastases and the growth of new tumors in many organs of the body eventually disrupt a vital body function, which is the cause of death. Learn more about bone metastases.

How is Cancer Classified?

Cancers are medically classified according to the organ or kind of tissue in which the tumor originates. The four major categories of cancers are carcinomas, sarcomas, leukemias, and lymphomas. Within these major categories are numerous subgroups that generally describe the organ in which the cancer originates, such as adenocarcinoma of the stomach or oat cell carcinoma of the lung. About half of all human cancers originate in one of four organs: the lung, breast, prostate, or colon, which is why so much research is devoted to these particular forms.

How Cancers Start

Cancer does not develop all at once in a cell. Several changes must occur in the genetic information (i.e., DNA) carried in a single cell before it can become a cancer cell and multiply into a tumor. Cells change their abnormal growth properties one step at a time; each genetic change pushes the cell further along the spectrum of abnormal growth. Not all cells acquire the same genetic changes nor can anyone predict when the changes will occur. That explains to some extent why some cancers develop and grow rapidly and cause death in months; other cancers may grow so slowly that the person eventually dies from a cause other than cancer.

What are the Stages of Cancer?

• In stage I, cancer cells can be distinguished from normal cells. The cancer cells are still localized (usually referred to as cancer in situ) and surgical removal of the tumor usually results in a cure.
• In stage II, tumor size is increased. The cancer cells may or may not have spread to the lymph nodes, and begun encroaching on nearby tissue.
• By stage III, the cancer cells have continued to grow and extend into the area around the tumor.
• In stage IV, tumors have spread to other parts of the body.

Symptoms Suspicious of Cancer

In its early stages, cancer typically does not have any symptoms. However, here are some important body signals that might indicate the presence of cancer and should be brought to the attention of your doctor:

• Any changes in bowel habits. If you've always had normal bowel movements but suddenly develop constipation that continues for two weeks or more, especially if it's accompanied by intermittent attacks of diarrhea. Cancer of the bowel often presents itself in this way. Blood in the stool, even if attributed it to hemorrhoids, should also be checked out because hemorrhoids can coexist with more serious colon problems. Finally, if normally bulky stool has become thin and ribbonlike, the reduced caliber may be due to a growth that's narrowing a portion of the colon.
• An open sore or a persistent rash that does not clear up may reflect skin cancer.
• Blood or discharge from any body orifice-vomited, coughed up, in the urine, from the vagina, or in the stool.
• Any persistent bump or lump anywhere you find it-in the breast, on the skin, in the testicle, under the arms, neck, groin, or abdomen.
• Pain in the stomach, either when you're hungry or after eating, indigestion, or difficulty swallowing.
• A chronic, nagging cough, with or without sputum and especially (but not necessarily) accompanied by any amount of blood, however small, is a sign—especially in smokers. So is persistent hoarseness.
• A low-grade fever without an obvious cause (doctors called it FUO—fever of unknown origin) that continues for longer than a week or two warrants a visit to your doctor. It may be due to something as innocuous as an infection behind a tooth, but it may also reflect a serious process such as a diseased heart valve, an abscess somewhere in the body—or a hidden malignancy.
• Weight loss for no apparent reason. The problem may be due to a medication, an overactive thyroid, an undiagnosed infection—or, again, a hidden cancer.

Although these signs may be symptoms of other conditions, they should not be ignored because they are not causing any pain—at the moment. Cancers often don't hurt in the early stages.

 

‹ previous section | next section ›