The uncontrolled growth of abnormal cells which have mutated from normal tissues. Cancer can kill when these cells prevent normal function of affected vital organs or spread throughout the body to damage other key systems. There are at least 200 different kinds of cancers, which can develop in almost any organ.

Alternative Names

Carcinoma; Malignant tumor

Causes, incidence, and risk factors

In general, cancer appears to be caused by abnormal regulation of cell growth. Typically, the growth of cells in the body is strictly controlled -- new cells are made as needed to replace older ones or to perform needed functions. If the balance of cell growth and death is disturbed, cancer may occur. Problems in the regulation of cell growth can be caused by abnormalities of the immune system, which normally would detect and stop aberrant growth. Other potential causes of cancer include radiation, sunlight, tobacco, certain viruses, benzene, certain poisonous mushrooms, and aflatoxins amongst many others. The three most common cancers in men are prostate cancer, colon cancer and lung cancer. While in women, the three most frequently occurring cancers are breast cancer, colon cancer and lung cancer. Certain cancers are more common in particular geographic regions. For example in Japan, there are many cases of gastric (stomach) cancer while in the U.S. this type of cancer is relatively rare. Dietary differences may account for the variance. Another tumor that is much more prevalent in other parts of the world compared with the U.S. is liver cancer. This cancer is often caused by viral infections with Hepatitis B and C, and is also linked with exposure to aflatoxins, which can be found in certain contaminated foods.

Signs and tests

Like symptoms, the signs of cancer vary based on the type and location of the tumor. Most cancer is diagnosed by biopsy. Depending on the location of the tumor, the biopsy may be a simple procedure or a serious operation. Most patients with cancer undergo CT scans to determine the exact location of the tumor or tumors. Common tests include:

Treatment

Treatment also varies based on the type of cancer and its stage. The stage of a cancer refers to whether or not the tumor has spread from its original location. If the cancer is confined to one location and has not spread, the goal for treatment would be surgery and cure. This is often the case with skin cancers. If the tumor has spread to local lymph nodes only, sometimes these can also be removed. If all of the cancer cannot be removed with surgery, the options for treatment include radiation, chemotherapy, or both. Some cancers require a combination of surgery, radiation and chemotherapy.

Support groups

The diagnosis of cancer often causes a lot of anxiety and can affect one's entire life. There are numerous support groups for cancer patients which can be found by searching the Internet or calling the American Cancer Society. Research has found that breast cancer patients who participate in support groups survive longer than those who do not and this may be true for other cancers as well.

Expectations (prognosis)

Prognosis varies widely among different types of cancer. Even amongst people with one particular type of cancer, the outcome varies depending on the stage of the tumor at diagnosis. Some cancers can be cured, some that are not curable can still be treated well and some patients can live for many years with the cancer. Other tumors are rapidly fatal.

Complications

Spread of the cancer and death.

Calling your health care provider

You should contact your doctor if you develop signs or symptoms of cancer.

Prevention

Avoiding smoking or quitting smoking if you do smoke is one of the best ways to prevent cancer. Many cancers can be prevented by avoiding other risk factors such as excessive exposure to sunlight and heavy drinking. In addition, some cancers can be prevented by eating a healthy diet which is low in fat and high in fiber.