Cancer

While more people die of heart disease in the U.S. than cancer, cancer is still one of the most feared diagnoses a person can receive. There are good reasons for this. Cancer's ability to cause pain is notorious and some of the treatments used to fight the disease can themselves make you very sick. Fortunately, not all cancers fall into such extreme categories. And while no cure is in sight, a lot of progress has been made in prevention, treatment and controlling cancer pain as well as the side effects of treatment.

Cancer isn't one disease but many. It occurs when normal cells begin dividing uncontrollably and start pushing beyond their usual boundaries. Treatment depends on where a particular cancer is located in the body, how aggressively it is growing and whether or not it has spread to distant tissues.

Tumors that grow but are incapable of encroaching on nearby tissues are considered benign, and unless they interfere with something important like breathing, or they occur in tight spaces like the brain, are generally left alone. Tumors that have the potential to either invade adjoining tissues or spread farther away (metastasize) are considered malignant.

Most cancers are not hereditary in the same way as, say, your eye color or blood type. But all cancers begin when mistakes start to accumulate in the so-called regulatory genes of a cell. Among other things, these genes control how a cell grows and, just as important, they instruct the cell to self-destruct when it is damaged. Genes may be damaged by tobacco smoke, certain chemicals, direct sunlight or other forms of radiation, hormones, viruses, germs, various compounds in food or even the ordinary process of aging.

For years, cancer researchers thought that damage to the growth genes was the most important reason cancers developed. The idea was that it was like pushing on the accelerator of a car, feeding it more gas so that it could go faster. Gradually, however, it became clear that the genes involved in cell death are important too. Damaging them would be like disabling the brake on a car, allowing it to gain speed—especially if it were already going downhill.

At any rate, when the normal balance between cells that are dividing and those that are dying is disrupted, the body somehow overlooks the danger signs and the cancer begins to grow. Prostate cancer is the most common malignancy (apart from skin cancers) in American men, followed by cancers of the lung, colon and rectum. Breast cancer is most common in women, followed by cancers of the colon, rectum and lung. But lung cancer continues to be the biggest killer among men and women.

There is a silver lining in these grim numbers. Cancer statistics released in 2006 showed that the overall death rate from cancer in the U.S. has fallen 1.1% since the mid-1990s. That may not seem like a lot, but at least the numbers are moving in the right direction. (Death rates from cancer in the U.S. actually increased throughout the 1970s.) Some of the largest decreases are in breast cancer (a drop of 3.1% in the death rate since the late 1990s) and colon cancer (a drop of 1.9% in the death rate among women and 1.3% in the death rate among men).

The Importance of Early Detection.

Most cancers take many years to develop, so catching them at an early stage—before they have invaded surrounding tissue or, worse, have begun to spread to the farthest reaches of the body—is vital. Unfortunately, tumors in the early stage of malignancy generally don't cause any symptoms. They can be difficult to detect.

One of the reasons why the death rate from cervical cancer has fallen so dramatically in the developed countries of the world since the 1940s is because doctors can easily detect (through a Pap smear) and remove (through a biopsy) abnormal cells in the cervix before they even become cancerous. Similarly, the increasing use of colonoscopies to find and remove precancerous intestinal polyps has contributed significantly to the recent decline in the death rate from colon cancer.

Treatment: Current and Future.

For decades doctors have had three main options for treating cancer: surgery, chemotherapy or radiation. The earlier a cancer is found, the greater the chance that surgery alone will suffice. Chemotherapy is used if doctors suspect some cancer cells may have traveled away from the original tumor site or if blood cells—which travel all over the body naturally—have turned cancerous, as in leukemia. Radiation is used to destroy malignant tissue that surgeons either can't get at or might have been missed during the operation.

As scientists have learned more and more about the genetic makeup of various cancers, however, more targeted treatments are being developed. One of the first such therapies was the drug Gleevec, which was approved by the Food and Drug Administration in 2001 and has proven very effective against certain forms of leukemia because it targets the exact chromosomal abnormality that leads to those cancers.

There still aren't any magic bullets that will eradicate all tumors, but it's undeniable that a combination of factors—from the wider availability of screening tests to greater efforts to quit smoking to the combination of traditional and gene-based treatments—have, in the early years of the 21st century, helped decrease the overall death rate from cancer.

—Christine Gorman