Transcript Cancer Concerns

Cancer Concerns
MONICA BROWN, PHD
CANCER EPIDEMIOLOGIST
THE CALIFORNIA CANCER REGISTRY
CANCER EPIDEMIOLOGY (EPI-272)
JANUARY 21, 2011
UCD, DEPT OF PUBLIC HEALTH
What Drives the Public’s Concern of the Clustering
of Cancers in Communities and Workplaces?
 There is considerable public concern that environmental
exposures cause an excess in cancers in some communities.
 The public believes environmental pollutants/toxins increase
risk of cancer - although, there’s no evidence that there is
increased risk to the general population in amounts that are
typically present in the air, soil or drinking water.
 Cancer clusters may be suspected when people notice that
several family members, friends, neighbors or co-workers
have been diagnosed with cancer, when the distribution of
cancers may be “normal” given the age, sex, race/ethnic and
lifestyle of that group.
… continued
 Other phenomena that may drive suspicion of
environmental cancer clusters are...

Media reports sensationalized cancer clusters

Distrust of government, manufacturing and business

Fear that we’ve created an environment filled with hazards
that is causes us and our families harm
The perceived inability to control cancer risk and
environmental hazards
Ever changing and varied Public Health (PH) messages


What We know
 Cancers are common!
 Cancer incidence varies by age, sex, race/ethnicity & risk
factors
 Cancers are complex diseases - PH has oversimplified
cancer


Use of the singular – “cancer” instead of “cancers”
Lumping all non-clinical risk factors as “environmental”
 Communities members are often similar - age, SES,
race/ethnicity & lifestyles – these factors contribute more
to cancer incidence than shared environment
 Knowledge of cancer causes, its distribution and
prevention varies greatly in the general public –

PH has done a poor job educating the public about cancer;
therefore the public has many misconceptions about cancer &
cancer clusters
Common Misconceptions about Cancer
Cancer is uncommon
Cancer is too common - 1 in 5 Californians
will have a cancer in their lifetime
Cancer is one disease
Cancer is a general term for many diseases – most
with different etiologies
Scientist understand cancer
development
The etiology of many cancers is unknown
Young people shouldn't get cancer
Cancers can be found in every age group
All cancers can be caused by a single
factor
Cancers are thought to be caused by a combination
of factors
Exposure to a known carcinogen and
the onset of cancer is certain and
immediate
Exposure to a carcinogen and the onset of cancer is
not certain, other factors, some known, may be
required. When cancer does develop, the onset can
be decades from exposure
Environmental exposures are the
primary cause of cancer
Lifestyle has been associated with 68% of the most
prevalent cancers
Causes of Cancer
Family History/Genetics
•Family History 5%
•Prenatal Factors/Growth 5%
•Reproductive Factors 3%
Family
History/Genetics
13%
Environment/
Occupation
19%
Lifestyle
68%
Environmental/Occupation
•Occupation 5%
•Viruses/other biologics 5%
•SES 3%
•Pollution 2%
•Radiation 2%
•Other 2%
Lifestyle
•Tobacco Use 30%
•Diet 10%
•Physical Inactivity 5%
•Alcohol Use 3%
•Other 20%
Source: Harvard Report on Cancer Prevention, 1996
Age-Specific Incidence Rate (ASIR) for most
prevalent cancers
90
80
70
ASIR per 100,000
60
50
40
30
20
10
0
<5
5-9
Female Breast
10-14
15-19
20-24
Prostate
25-29
30-34
35-39
Female Lung
40-44
45-49
50-54
Age at Diagnosis
Male Lung
55-59
60-64
65-69
70-74
Female Colorectal
75-79
80-84
85+
Male Colorectal
Common Misconceptions about
Cancer Clusters
Clustering is uncommon
Clustering of health events is
common - some random (1%) some
not. Shared social-demographic
characteristics and/or similar
lifestyles explains some health
event clustering.
Several cancer cases make a single
cause cluster
We expect a certain number & certain
types of cancers in every
neighborhood/workplace.
If there are several cases of cancers in
a community, of different types, they
must come from the same source.
If there are several different types of
cancers in a community, there are likely
several different causes.
Examples of Documented Cancer Clusters
Cluster
Adenocarcinoma of vagina
among young women
Angiosarcoma of the liver
among factory workers
Mesothelioma among Native
American silversmiths
Kaposis sarcoma among
young men
Characteristic Agent
Rare
DiethylIncr dz freq
stilbestrol
Vinyl
Chloride
Rare
Rare
Incr dz freq
unique pop
asbestos
HIV
The California Cancer Registry
 The California Cancer Registry (CCR) is
administered by the California Department of
Public Health (CDPH).
 The CCR is a true population-based registry.

Cancer reporting is mandated for hospitals and physicians.
 Data collected by the registry are used:
 To monitor incidence and mortality.
 For research into the causes, cures and prevention of
cancer;
 To produce reports including the state and regional annual
reports and the American Cancer Society’s Cancer Facts
and Figures; and
 The evaluation of community cancer concerns.
When a Californian has a Cancer Concern: the
Role of the CCR
 The CCR and it’s regional cancer registries
respond to numerous requests for evaluation of
community and workplace cancer concerns.
 The registry’s role is to statistically assess whether
the number of cases of targeted cancers observed
in a community or workplace are significantly
greater than what would be expected.
 If there is a statistically significant excess of cases,
report to the Environmental Health
Investigations Branch (EHIB) of CDPH who will
investigate.
The Role of the CCR, continued
 The CCR does not:
 Conduct epidemiologic “outbreak”, clinical or laboratory
investigations.
 On-site surveys of residents or employees to assess risk.
 Direct others in exposure assessments.
 Coordinate the efforts of other state and county agencies
in their investigations.
We define a Cancer Cluster as…
AN AGGREGATION OF CANCER CASES THAT
HAS BEEN DETERMINED TO BE UNUSUAL
WHEN COMPARED TO THE CANCERS THAT
WOULD BE EXPECTED IF THE GROUP OF
LOCATION IN QUESTION HAD THE SAME
CANCER RATES AS THE UNDERLYING
POPULATION.
THE CLUSTER MUST DIFFER SUBSTANTIALLY
FROM THE EXPECTED PATTERN IN NUMBER,
TYPE, OR THE AGE OF CASES.
The CDC defines a Cluster as …
AN UNUSUAL AGGREGATION, REAL OR
PERCEIVED, OF HEALTH EVENTS THAT
ARE GROUPED TOGETHER IN TIME OR
SPACE AND THAT ARE REPORTED TO A
HEALTH AGENCY*
* Guidelines for Investigating Clusters of
Health Events, 1990,
Centers for Disease Control and Prevention
Procedures
1.
2.
3.
4.
5.
6.
7.
Obtain Information from Informant
Provide Cancer Education and Information
Assess Cancer Concern - Determine if Further
Analysis is Needed
Explain Procedures, Limitations of Methods and
Provide a Timeline
Consult and Notify Relevant Officials
Perform Assessment
Communicate the Results of Assessment
Step One:
Obtain
Information
 Caller’s name & address;
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
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
affiliation (community member)
Number of specific cases observed
Cancer type(s) observed
Age, sex, race/ethnicity of cases
Geographic area or group
Time period of concern
Method of observation – how did
the caller learn of the cases
Step Two:
Provide
Cancer
Education &
Information
 Education
 The frequency of specified cancers in their
community or County
 Risk factors for specified cancers
 If knowledgably, discuss agent and/or
exposure
 Information
 American Cancer Society (ACS)
 Centers for Disease Control and Prevention
(CDC)
 The National Institutes of Health (NIH)
 Agency for Toxic Substances and Disease
Registry (ATSDR)
Note: Do not assume that everyone has access to or
can use the internet
Step Three: Determine if Further Analysis is Needed
Indications for
Statistical Evaluation
Other Considerations
 Are cancers unusual in number,
 Is the request coming from a
type or age of patients?
 Has a potential carcinogenic
agent been identified?
another State agency or from a
County Health Department?
 Is informant representing a
community or workplace action
group?
 Are children involved?
 Is this perceived cancer cluster
“political” or is it already being
followed by the press?

If a specific exposure is
suspected – test 1st – call County
Environmental Health,
Environmental Protection
Agency (EPA) or if workplace,
Occupational Safety and Health
Agency (OSHA)
 Is there a plausible exposure
pathway?
Step Three: Determine if Further Analysis is Needed
Unusual
Cancers
Carcinogenic
Agent
or
+
Increased
Cancer
Frequency
Biologic
Plausibility
or
Occurrence
in Unique
Population
+
CCR
Documented
Cases
Further Action Warranted
Step Four:
Explain
Procedure,
Limitations &
Provide
Timeline
 Procedure
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We use registry data to confirm case information &
determine clinical characteristics of cancers
We use census data for denominators (population
at risk)
Perform calculations, write report to county &
state.
In the event of a statistically significant excess of
cancers, we refer case to EHIB for investigation
 Limitations
 CCR will not contain most recently diagnosed
cases
 Only a substantial increase in risk is likely to be
detected
 We lack information on length of residence
and risk factors that may contribute to
developing cancer
 Timeline
 1-3 months
Workplace Cancer Concerns: Barriers to Evaluations
 Obtaining appropriate information on ill & well
(population at risk) employees from employers is difficult
to impossible.
 If necessary, must obtain permission from employees to
access their medical records.
 Assessing biologic plausibility: Is the suspected agent at
work associated with increased risk of reported cancers?
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Does workplace exposure have an impact? direct vs. indirect; length of
exposure (workday/year(s)); mode of exposure (eat/drink, inhale etc.)
What other risk factors could increase risk of developing reported
cancers – smoking, drinking & diet – that cannot be assessed?
 Separating endemic cancers from those reported: what
cancers would be “normal” for this employee group.
 Are there behaviors that are common in this employee
group?
Step Five:
Consult and
Notify
Relevant
Officials of
Report
 Management hierarchy of CDPH
 County Health Officer
 Workplace management
Step Six:
Perform
Assessment
 Define geographic area by census tract
 Review observed cases
 Generate expected number of cancers
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
5-year type-, age-, sex- and race-specific rates
for the state or region
U.S. Census Bureau year 2000 population
data for the census tract(s)
 Compare cases observed and
expected, calculate 99% confidence
interval
 Determine whether a statistically
significant excess is found
Step Seven:
Communicate
Results
 Write letter or report describing
concern and results of
assessment to the …



Informant
County Health Officer
CSRB management hierarchy
 If results show a statistically
significant excess in cases,
include …
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
EHIB
CDPH public affairs office
Challenges in Communicating Results
 Science
 Scientific evidence is inconclusive, contradictory and ever-changing
 Current scientific evidence is not absolute. Therefore, we cannot give
definitive answers.
 Scientific method - descriptions of methodological limitations and
results can sound evasive.
 Complicated scientific Concepts:
 Random events
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
1% of all census tracts would have higher or lower cancer rates simply by
chance
 No one has ever called me and said “… there’s too few cancers in my
neighborhood”.
public seemingly can only grasp concept if discussing the lottery.
… continued
 Epi & Stat Concepts
 Often case and/or population numbers are too small for appropriate
statistical analysis, and we are unable to conduct analysis.
 sometimes viewed as demeaning the current number of cases.
 sometimes viewed as evasive or manipulative.
 For environmentally based cancer concerns, we examine only related
cancers not “all cancers” due to etiologic differences in cancers –
often public thinks all cancers are germane.
 Causality - if cluster confirmed statistically, doesn’t mean cancer is
due to a single causal pathway.
 Epidemiologists & Statisticians (us)


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Objectiveness viewed as lack of empathy.
Expertise viewed as “Ivory Tower’ism”
We are not good at saying we don’t know
The Seven Cardinal Rules of Risk Communication
Rules
1.
2.
3.
4.
5.
6.
7.
Accept and involve the public
as a partner.
Plan carefully and evaluate
your efforts.
Listen to the public's specific
concerns.
Be honest, frank, and open.
Work with other credible
sources.
Meet the needs of the media.
Speak clearly and with
compassion.
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Your primary goal is to produce an informed public,
not to defuse public concerns.
Different goals, audiences, and media require
different actions.
People often care more about trust, credibility,
competence, fairness, and empathy than statistics
and details.
Trust and credibility are difficult to obtain; once
lost, they are almost impossible to regain.
Conflicts and disagreements among organizations
make communication with the public more difficult.
The media are usually more interested in politics
than risk, simplicity than complexity, danger than
safety.
Always acknowledge the tragedy of an illness or
death. People can understand risk information, but
they may still not agree with you; some people will
not be satisfied.
From: The Seven Cardinal Rules of Risk Communications, Covello and Allen 1988
In Conclusion
 Cancer clusters DO occur in communities, but are
difficult to investigate and nearly impossible to prove.

Our tools to investigate are crude and we often lack pertinent
information or time to see the natural history of events.

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Cancer never 1st disease manifestation in true cluster
From exposure to diagnosis can be 20 – 50 years, depending on
carcinogen
Most prevalent cancers are not strictly caused by environmental
exposures – i.e., lung or prostate cancer
Ignorance: what we think is harmless today, tomorrow we may
learn is dangerous.
 We must take responsibility and precautions to
safeguard our health.
For More Information on Cancer Clusters
 ACS:
http://www.cancer.org/Cancer/CancerCauses/OtherCa
rcinogens/GeneralInformationaboutCarcinogens/cance
r-clusters
 NIH:
http://www.cancer.gov/cancertopics/factsheet/Risk/cl
usters
 CDC: http://www.cdc.gov/nceh/clusters/
 ATSDR:
http://www.atsdr.cdc.gov/csem/cluster/docs/clusters.p
df
Harvard School of Public Health, Disease Risk Profile:
http://www.diseaseriskindex.harvard.edu/update/hccpquiz.pl?lang=english&func
=home&page=cancer_index
Thank You!