C ancer has always figured uniquely in the diseases of mankind. For centuries people spoke of it only in whispers, or not at all, as if the disease were not only dreadful but somehow shameful as well. Today, the picture is changing rapidly. More than half of those diagnosed with cancer will reach the important five-year survival landmark. (The five-year survival rate is a common measure of progress in the early detection and treatment of cancer.) Also, much of the mystery that cloaked the disease has been dissipated.

Of course, cancer remains a formidable enemy. Cancer is the second leading cause of death in the United States; it causes one in four deaths. Some 1.2 million new cases of cancer are diagnosed annually in the United States, and an estimated 560,000 people die of it each year. The National Institutes of Health estimate that cancer costs society more than $100 billion annually, in terms of direct medical costs and loss of productivity.

But in context, the picture is not as bleak as it might seem. At the beginning of the twentieth century, survival from cancer was relatively rare. At the end of the 1930s, the five-year survival rate was one in five or fewer. Ten years later it had shot up to one in four, and in the mid-fifties to one in three. The survival rate for some of the more widespread cancers has leveled off despite the best efforts of physicians to devise better forms of treatment. For such cancers, which include those of the breast, colon, and rectum, improvements will come through earlier detection and even prevention. Dr. Richard S. Doll, Professor of Medicine at Oxford University, has said that we could prevent 40 percent of men's cancer deaths and 10 percent of women's simply by applying what we already know. For example, according to the American Cancer Society, the risk of death from lung cancer is 15 to 20 times greater among men who smoke cigarettes than among men who have never smoked. The relative risk of lung cancer among women smokers is five times that of women who have never smoked.

Considerable progress is being made on many fronts in the war against cancer. It ranges from advances in early detection to breakthroughs in treatment. Between 1955 and 1992, for example, the death rate from cervical cancer—which used to be one of the most common causes of death in American women—declined by 74 percent, mostly because of the widespread use of the Pap test, which can detect the disease at an early stage. At the same time, children with acute lymphocytic leukemia, which used to be invariably fatal in weeks or months, have benefited from new therapies. The probability of an extended remission or cure was more than 75 percent in the mid-1990s; it was just 5 percent in 1960. Similar advances in the treatment of a cancer of the lymph system called Hodgkin's disease have improved the five-year survival rate from 25 percent at the end of World War II to about 81 percent today.

Major Forms of Cancer

T he following material includes discussions of the major forms of cancer with the exception of those cancers that affect women only. For additional information on many kinds of tumors for which surgery may be indicated, see also Ch. 20, Surgery .

Cancer's Seven Warning Signals*

1. 1. Change in bowel or bladder habits
2. 2. A sore that does not heal
3. 3. Unusual bleeding or discharge
4. 4. Thickening or lump in breast or elsewhere
5. 5. Indigestion or difficulty in swallowing
6. 6. Obvious change in wart or mole
7. 7. Nagging cough or hoarseness

If you have a warning signal, see your doctor without delay.

*from the American Cancer Society

Detection

X rays of the stomach and examination of the stomach interior by gastroscopy usually locate and define the cancerous area; they may also reveal another cause of the symptoms, such as a peptic ulcer. During the physical examination, the physician may find a tissue mass and tenderness in the stomach area. The laboratory report usually will show signs of anemia from blood loss, the presence of blood in a stool sample, and the level of hydrochloric acid in the stomach; a lack of hydrochloric acid is found in more than half the stomach cancer patients. A biopsy study of the suspected tissue usually completes the diagnosis.

Therapy

Unfortunately, because of the insidious nature of stomach cancer, the disease becomes easier to diagnose as it progresses. By the time cancer has been confirmed, the most expedient form of treatment is surgery to remove the affected area of the stomach. If the cancer is small and has not spread by metastasis to lymph nodes in the region, the chances are relatively good that the patient will survive five years or more; the odds against surviving five years without surgery are, by comparison, about 50 to 1 at best. Chemotherapy treatments may be used in cases where surgery is not feasible, but the use of medicines instead of surgery for stomach cancer is not a routine procedure and generally is not recommended.

Occasionally, a stomach tumor is found to be noncancerous. The tumor may be a polyp, a leiomyoma (a growth consisting of smooth muscle tissue), or a pseudotumor (false tumor), such as an inflammatory fibroid growth. Such benign tumors produce symptoms ranging from gastric upset to internal bleeding and should be removed by surgery.

Causes

Many possible factors have been suggested as causes of stomach cancer. Dietary factors include hot food and beverages, as well as fish and smoked foods. Food additives have been implicated despite the fact that the incidence of stomach cancer has been declining during the period in which the use of additives has been increasing. Cured meats and cheeses, preserved with nitrites to retard spoilage, reportedly foster the development of carcinogenic chemical compounds in the digestive tract.

On the other hand, the widespread use of refrigeration has been offered as an explanation for the declining incidence of stomach cancer, since refrigeration reduces the need for chemical food preservatives.

Beyond the influence of diet, medical epidemiologists have found that genetic factors may play a role in the development of stomach cancer. Statistical analysis of large population studies of stomach cancer shows a tendency for the disease to occur in persons with blood type A, or with below-normal levels of hydrochloric acid in the stomach, or with inherited variations in the stomach lining. There also seems to be a good possibility that stomach cancers evolve from noncancerous changes in the stomach lining, as from polyps or peptic ulcers.