Download - Cancer Concerns
MONICA BROWN, PHDCANCER EPIDEMIOLOGIST
THE CALIFORNIA CANCER REGISTRY
Cancer Concerns
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 factorsCancers 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 uncommonCancer 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
Lifestyle68%
Environment/Occupation
19%
Family History/Genetics
13%
Lifestyle•Tobacco Use 30%•Diet 10%•Physical Inactivity 5%•Alcohol Use 3%•Other 20%
Environmental/Occupation•Occupation 5%•Viruses/other biologics 5%•SES 3%•Pollution 2%•Radiation 2%•Other 2%
Family History/Genetics•Family History 5%•Prenatal Factors/Growth 5%•Reproductive Factors 3%
Source: Harvard Report on Cancer Prevention, 1996
0
10
20
30
40
50
60
70
80
90
<5 5-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 80-84 85+
Age at Diagnosis
ASIR
per
100
,000
Female Breast Prostate Female Lung Male Lung Female Colorectal Male Colorectal
Age-Specific Incidence Rate (ASIR) for most prevalent cancers
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 Characteristic AgentRare
Incr dz freqAngiosarcoma of the liver among factory workers Rare
Vinyl Chloride
Mesothelioma among Native American silversmiths Rare asbestos
Incr dz frequnique pop
Diethyl-stilbestrol
Adenocarcinoma of vagina among young women
Kaposis sarcoma among young men 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.
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.
We define a Cancer 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*
The CDC defines a Cluster as …
* Guidelines for Investigating Clusters of Health Events, 1990, Centers for Disease Control and Prevention
Procedures
1. Obtain Information from Informant2. Provide Cancer Education and Information 3. Assess Cancer Concern - Determine if
Further Analysis is Needed4. Explain Procedures, Limitations of Methods
and Provide a Timeline5. Consult and Notify Relevant Officials6. Perform Assessment7. Communicate the Results of Assessment
Step One: Obtain Information
Caller’s name & address; affiliation (community member)
Number of specific cases observed
Cancer type(s) observedAge, sex, race/ethnicity of casesGeographic area or groupTime period of concernMethod 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
Indications for Statistical Evaluation Other Considerations Are cancers unusual in
number, type or age of patients?
Has a potential carcinogenic agent been identified? 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?
Is the request coming from a 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?
Step Three: Determine if Further Analysis is Needed
Step Three: Determine if Further Analysis is Needed
Unusual Cancers
IncreasedCancer
Frequency
Occurrencein UniquePopulation
or or
+CCR
Documented
Cases
BiologicPlausibility
Further Action Warranted
+Carcinogenic Agent
Step Four: Explain Procedure, Limitations & Provide Timeline
Procedure 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? 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 OfficerWorkplace management
Step Six: Perform Assessment
Define geographic area by census tract
Review observed casesGenerate expected number of
cancers 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 … 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 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) Objectiveness viewed as lack of empathy. Expertise viewed as “Ivory Tower’ism” We are not good at saying we don’t know
Rules
1. Accept and involve the public as a partner.
2. Plan carefully and evaluate your efforts.
3. Listen to the public's specific concerns.
4. Be honest, frank, and open.5. Work with other credible
sources.6. Meet the needs of the
media.7. Speak clearly and with
compassion.
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.
The Seven Cardinal Rules of Risk Communication
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.
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/OtherCarcinogens/GeneralInformationaboutCarcinogens/cancer-clusters
NIH: http://www.cancer.gov/cancertopics/factsheet/Risk/clusters
CDC: http://www.cdc.gov/nceh/clusters/ ATSDR:
http://www.atsdr.cdc.gov/csem/cluster/docs/clusters.pdf
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!