What is cancer?
What are the risk factors for cancer?
How long do cancers take to develop?
What are cancer clusters?
How are an excessive number of cases determined?
What about exposures to contaminants in the area being studied in a cancer cluster investigation?
Who should people contact if a cancer cluster is suspected?

What is cancer?

Cancer is an uncontrolled growth and spread of abnormal cells any place in the body.  There are many types of cancer with a variety of causes. Cancer in general is common.  It is the second leading cause of death in Florida as well as the United States.  The American Cancer Society says one in three people will get cancer during their lifetime.

What are the risk factors for cancer?

The risk for most types of cancer goes up with age.  Therefore, it is important to consider age when trying to see what may be the cause of cancer.  Other risk factors can add to the chance of getting cancer.  These risk factors include where someone lives, their family's health history, and personal health habits, such as eating a healthy diet and getting enough exercise.  It is important to be aware of these factors when trying to understand why and how often cancer occurs in an area.

Cancers in different parts of the body are often caused by different risk factors.  For example, asbestos is known to be a risk factor for lung cancer.  However, asbestos is not a risk factor for breast cancer.  Exposure to radiation or benzene is a risk factor for certain types of leukemia (blood cancer).  They are not, though, for colon cancer.  What you eat and how active you keep yourself are factors for colon cancer.  How much exposure to sunlight you get is a risk factor for skin cancer.  Yet for most other cancers, exposure to sunlight is not a risk.  In addition, the level and duration of exposure plays a part in the development of cancer. For instance years of exposure to low levels of arsenic is a risk factor for kidney cancer while a one time low level exposure to arsenic is not.

Cancer is often not caused by only one factor.  Each type of cancer is almost always caused by a mix of factors.  For most types of cancer, how well the body responds goes down as people grow older.  Therefore, most types of cancer are far more common in older people.

Because of new, better ways to treat cancer, there is now more hope for a cure when someone finds out they have cancer.  With many types of cancer, cases can be cured when caught early.  Some of these types are cancer of the breast, cervix and colon.  Making sure you get the right kind of screening tests can possibly help detect and treat the disease sooner and help you have a life free from cancer.

How long do cancers take to develop?

The development of cancer is often very slow.  The time between exposure to one or more cancer-causing agents till the onset of cancer, often depends on the type of cancer.  However, in general, it takes approximately 10 to 30 years for the disease to be detectable.

Cancers that are diagnosed now are usually related to many years of certain habits (such as smoking) or exposures to cancer-causing agents many years ago.

What are cancer clusters?

When people learn that several friends, family members or neighbors have found out they have cancer, cancer clusters are often suspected.  Cancer clusters are also sometimes suspected when people get cancer that work at the same place or who have some other factors in common.  Cancer clusters are higher numbers of the same type of cancer cases than expected within a period of time and area.

An excess of cancer is more likely to be a cluster if it occurs in a group of people where these cancers are not likely to occur.  For example, we would not expect to find many cancer cases among children in a small geographic area.  We also would not expect to find lung cancer in nonsmokers or breast cancer in men.  These cases are simply not expected for those kinds of groups. Cancer cases are also more likely to be a cluster if they involve a single type of cancer or a rare type of cancer.

Because all cancers are not caused by the same factors, what was thought to be a cancer cluster usually is found to have occurred by chance.  The cases rarely are found to relate to factors in the environment.

How are an excessive number of cases determined?

Someone who is studying a suspected cluster must know how many people there are in a community. They must also know about the people's age, race, and sex. The investigator then computes the number of cancers that would be expected in that certain age, race or sex group. In true cancer clusters the number of cases found will be higher than the expected number by more than can be explained by chance. These are also called "meaningful" clusters. Other factors must be considered to decide if a cancer cluster truly exists. Possible cancer causes must also be considered to see if there is a link with the air, soil or water, or not.

What about exposures to contaminants in the area being studied in a cancer cluster investigation?

A cancer cluster investigation must show the following; (a) if possible chemicals are known to be in the environment or not, and if so, (b) if there is a way for people to come into contact with the chemicals, if so, (c) where people come into contact with chemicals (d) how long any contact occurred, (e) how much of a chemical people came into contact with, and (f) whether or not people live there who are more likely to be affected (such as children, old people, or someone who was sick before).

When an excessive number of cancer cases are found to exist in an area, the cluster investigation will look at records to answer these kinds of questions.  When there are no records, the investigation will recommend ways to keep track of this data in the future and steps to take to protect people.

Who should people contact if a cancer cluster is suspected?

If a cancer cluster is thought to exist, the first call should be made to the local county health department.  The county health department will follow the required Department of Health protocol or set of rules for further study.