Cancer Cluster FAQ
Contents
What is a cancer cluster?
A cancer cluster is defined as a greater than expected number of
cancer cases that occurs within a group of people, in a geographic area,
or over a period of time. A person may suspect that a cancer cluster
exists when several loved ones, neighbors, or coworkers are diagnosed
with cancer. However, what appears to be a cluster may actually reflect
the expected number of cancer cases within the group or area. When
considering the possible existence of a cancer cluster in your area, it
is important to remember a few key facts: 1) cancer is a common disease,
affecting about one in four people in their lifetime; 2) the term cancer
refers not to a single disease, but instead to a group of related yet
different diseases; 3) a cancer cluster may be due to chance alone, like
the clustering of balls on a pool table; and 4) an apparent cancer
cluster is more likely to be genuine if the cases consist of one type of
cancer, a rare type of cancer, or a type of cancer that is not usually
found in an age group.
How do I report a suspected cancer
cluster or obtain information on cancer statistics or trends for my
area?
Contact your local or state health department or state cancer
registry. These agencies provide the first level of response and have
the most current local data. Contact your local or state health
department through
http://www.cdc.gov/other.htm#states. Contact your state cancer
registry through
http://www.cdc.gov/cancer/npcr/statecon.htm#list.
Who responds to inquiries about a
suspected cancer cluster?
Local or state health departments, along with cancer registries,
provide the first level of response and have the most current local data
for the area. If needed, these agencies can request assistance from
federal agencies, including
When people contact CDC with concerns about a suspected cancer
cluster, CDC provides information and refers them to the appropriate
local or state health department or cancer registry.
How are suspected cancer clusters
investigated?
State and local health departments respond to cancer cluster reports
and inquiries about suspected clusters. A CDC survey (http://www.cdc.gov/nceh/clusters/cluster_status.htm)
revealed that most state health departments’ strategies for cluster
response are based on CDC’s “Guidelines for Investigating Clusters of
Health Events” (http://www.cdc.gov/mmwr/preview/mmwrhtml/00001797.htm)
with some modifications. Usually, a local or state health department
starts by gathering information about the suspected cancer cluster
including expected cancer rate, types of cancer, number of cases, and
the age, sex, race, address, occupation, and age at diagnosis of the
individuals with cancer. Information may be verified by contacting
patients and relatives or by obtaining medical records. This information
is then compared to census data and state cancer registry data to
determine if there is a higher than expected number of cases. Most
investigations do not proceed beyond evaluation of the gathered
information; however the local or state health department may perform a
more intensive assessment or comprehensive epidemiological study. The
decision to proceed to a more intensive investigation is usually based
on a set of rules developed by the health department.
What challenges regarding suspected
cancer clusters do investigators face?
Cancer cluster investigations are complex and difficult for several
reasons. Although any cancer case is one too many, suspected cancer
clusters often do not contain enough cases for investigators to do a
meaningful statistical analysis or reach a conclusion. Investigators
must choose the appropriate comparison population and decide how to
handle cases that move in or out of the area. Determining the cause of
cancer is complicated because exposure to cancer-causing agents may have
occurred many years before diagnosis. Therefore, assessing the amount
and type of cancer-causing agents an individual has been exposed to is
difficult. Unfortunately, cancer is often the result of a combination of
agents and risk factors that interact in a way that science does not yet
fully understand.
How do I find out if a suspected cancer
cluster is being investigated in my area? How do I find information on
an investigation in my area?
Contact your state cancer registry or your local or state health
department. Contact your state cancer registry through
http://www.cdc.gov/cancer/npcr/statecon.htm#list or your local or
state health department through
http://www.cdc.gov/other.htm#states. For information about public
health assessments conducted by ATSDR, search by state at
http://www.atsdr.cdc.gov/HAC/PHA/. For information on CDC
investigations, go to
http://www.cdc.gov/nceh/clusters/cluster_activities.htm.
What can I do to reduce my risk of
developing cancer?
Adopt a healthy lifestyle that includes avoiding tobacco use,
excessive alcohol consumption, and sun exposure. Increasing physical
activity, maintaining a recommended body weight, eating a healthful and
nutritious diet, and taking advantage of cancer screening also will
reduce your risk.
For more information about preventing cancer, visit
Where can I find more information about
cancer clusters?
For links to resources about cancer clusters in general, as well as
information about cancer registries and publications on cancer clusters,
visit
http://www.cdc.gov/nceh/clusters/resources.htm.
For an extensive overview of cancer clusters, including facts about
cancer, the environment, and heredity; methods used in investigating
suspected cancer clusters; guidelines for reporting suspected cancer
clusters; and a list of additional resources, visit the NCI’s Cancer
Cluster Web site at
http://cis.nci.nih.gov/fact/3_58.htm.
NCI has also collaborated with the National Institute for
Environmental Health Sciences to publish
Cancer and the Environment: What You Need to Know, What You Can Do.
This booklet addresses concerns about the connection between cancer and
exposure to toxic substances in the environment. It contains information
about which types of substances are either known to cause or likely to
cause cancer, and what can be done to reduce exposures to them. It also
explains how scientists discover which substances are likely to cause
cancer. The booklet provides an extensive overview of environmental
causes of or risk factors for cancer including lifestyle factors such as
diet and physical inactivity, certain medical drugs, hormones,
radiation, viruses, bacteria, and environmental chemicals that may be
present in the air, water, food, and workplace.
|
