What is cancer?

Cancer is a group of more than 100 different diseases that begin when abnormal cells in the body grow out of control. Normally, cells grow and divide to create new cells as they are needed to keep the body healthy. Sometimes this process of growing new cells does not work properly and cancer forms.

How does cancer start?

Normal cells become cancer cells because of damage to DNA. DNA is in every cell and directs all its actions. In a normal cell, when DNA gets damaged, the cell either repairs the damage or it dies. In cancer cells, the damaged DNA is not fixed, but the cell does not die like it should. Instead, this cell goes on making new cells that the body does not need.

How does cancer grow?

Abnormal cells can grow into a mass, or tumor. Not all tumors are cancerous. Tumors can be either malignant (cancerous) or benign (noncancerous). A malignant tumor, or cancer, can spread to other parts of the body and form other tumors.

Some cancers, like leukemia, rarely form tumors. Instead, these cancer cells are in the blood and blood-forming organs and flow through other tissues, where they grow.

Some cancers grow quickly; others may grow slowly over many years.

How common is cancer?

Cancer is a very common disease. One of every two men and one of every three women will be diagnosed with cancer at some time in their life. In New York State, nearly one in four deaths is due to cancer.

Cancer can occur at any age, but it is most often found in those people middle-aged and older. The number of people diagnosed with cancer has increased over the past 40 years. Most of this is due to an increase in the population and because people are living longer.

The most common cancers found in men, besides skin cancer, are prostate, lung and colon cancer. Breast, lung and colon cancers are the most common cancers found in women.

What causes cancer?

Different cancers have different causes and there are many factors that affect a person's chances of getting different types of cancer. Sometimes there is a family history of cancer. Scientists agree that people can get cancer through repeated long-term contact with carcinogens. These include tobacco, sunlight and indoor tanning devices (beds, booths, sunlamps) x-rays, and certain chemicals that may be found in the air, water, food, drugs and workplace. Our personal habits and lifestyle may also contribute to cancers. Scientists believe that about 30% of cancer deaths are due to tobacco use and between 25-30% of cancer deaths may be due to inadequate physical activity, obesity and an unhealthy diet.

How soon after exposure to a carcinogen does cancer appear?

Most cancers develop slowly in people. They usually appear between five to 40 years after exposure to a carcinogen. For example, lung cancer may not occur until 30 years after a person starts smoking. This long latency period is one of the reasons it is difficult to determine what causes cancer in humans.

What does it mean when something "is associated with" cancer?

It means that there is a link between the two, but there is no proof of cause and effect. More research needs to be done before we know for certain.