Monica Brown PhD Cancer Epidemiologist the California Cancer Registry Cancer Biology BIO183 Dr Hao Nguyen February 21 2011 Sacramento State University Dept of Biological Sciences ID: 1040942
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1. Community Cancer ClustersMonica Brown, PhDCancer Epidemiologist, the California Cancer RegistryCancer Biology (BIO-183), Dr. Hao NguyenFebruary 21, 2011Sacramento State University, Dept of Biological Sciences
2. What Drives the Public’s Concern of the Clustering of Cancers in Communities & 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.Cancer clusters may be suspected when people notice that several family members, friends, neighbors or co-workers have been diagnosed with cancer.Although the distribution of cancers may be “normal” given the age, sex, race/ethnic and lifestyle of that group.
3. … continuedOther phenomena that may drive suspicion of environmental cancer clusters are...Media reports sensationalized cancer clustersDistrust of government, manufacturing & businessFear that we’ve created an environment filled with hazards that is causes us & our families harmThe perceived inability to control cancer risk & environmental hazardsEver changing & varied Public Health (PH) messages
4. What We knowCancers are common! 1 in 5 Californians will have a cancer in their lifetimeCancers are complex diseases! Cancer is a general term for many diseases – most with different etiologies; many of which are unknownCancer incidence varies predictably by age, sex, race/ethnicity & risk factors.Community members can be similar in age, SES, race/ethnicity & lifestyles – these factors contribute more to cancer incidence than shared environment
5. What We know, continuedThere’s no evidence that carcinogens in amounts typically present in the air, soil or drinking water increases the risk of developing cancer in the general populationExposure 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.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
6. Causes of CancerLifestyle68%Environment/Occupation19%Family History/Genetics13%LifestyleTobacco Use 30%Diet 10%Physical Inactivity 5%Alcohol Use 3%Other 20%Environmental/OccupationOccupation 5%Viruses/other biologics 5%SES 3%Pollution 2%Radiation 2%Other 2%Family History/GeneticsFamily History 5%Prenatal Factors/Growth 5%Reproductive Factors 3%Source: Harvard Report on Cancer Prevention, 1996
7. Common Misconceptions about Cancer ClustersClustering is uncommonClustering 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 clusterWe 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.
8. Examples of Documented Cancer Clusters
9. Cancer Clusters in California
10. The California Cancer RegistryThe 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 & physicians.Every case diagnosed among residents reported since 1988Data collected by the registry are used:To monitor incidence & mortality.For research into the causes, cures & prevention of cancer; To produce reports including the state & regional reports; the American Cancer Society’s Cancer Facts & FiguresThe evaluation of community cancer concerns.
11. The CCR defines 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.
12. When a Californian has a Cancer Concern: the Role of the CCRThe 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.
13. 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.
14. CCR Procedures for Evaluation of a Reported Cancer Cluster
15. Step One: Obtain Information from InformantCaller’s name & address; affiliation (community member)Number of specific cases observedCancer type(s) observedAge, sex, race/ethnicity of casesGeographic area or groupTime period of concernMethod of observation – how did the caller learn of the cases
16. Step Two: Provide Cancer Education & Information to Informant EducationThe frequency of specified cancers in their community or CountyRisk factors for specified cancersIf knowledgably, discuss agent and/or exposure InformationAmerican 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
17. Indications for Statistical EvaluationOther ConsiderationsAre 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 an Evaluation is Needed
18. Further Action is Warranted
19. Step Four: Explain Procedure, Limitations & Provide Timeline to InformantProcedureWe use registry data to confirm case information & determine clinical characteristics of cancersWe 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 investigationLimitationsCCR will not contain most recently diagnosed casesOnly a substantial increase in risk is likely to be detectedWe lack information on length of residence and risk factors that may contribute to developing cancerTimeline: 1-3 months
20. Workplace Cancer Concerns: Barriers to EvaluationsObtaining appropriate information on ill & well (population at risk) employees from employers is difficult to impossible.Sometimes we must obtain permission from employees to access their medical records.Assessing biologic plausibility: Does the suspected workplace agent associated with increased risk of the reported cancers?Does workplace exposure have an impact? direct vs. indirectlength of exposure (workday/year(s))mode of exposure (eat/drink, inhale etc.) What other risk factors could increase risk of developing reported cancers, that cannot be assessed?smoking, drinking & dietWhat cancers would be “normal” for this employee population – given age, sex, race/ethnicity & lifestyleAre there behaviors that are common in this employee group?
21. Step Five: Consult and Notify Relevant Officials of ReportManagement hierarchy of CDPHCounty Health OfficerWorkplace management
22. Step Six: Conduct Assessment
23. Step Seven: Communicate ResultsReport results of evaluation to the …InformantCounty Health OfficerCSRB management hierarchyIf results show a statistically significant excess in cases, include …EHIBCDPH public affairs office
24. Challenges & Conclusions
25. Greatest Challenge: Communicating Results to the PublicScienceScientific evidence is inconclusive, contradictory and ever-changingCurrent 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 chanceNo 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.
26. Communicating Results to the Public, continuedEpi & Stat ConceptsOften 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.
27. Communicating Results to the Public, continuedEpidemiologists & Statisticians (us)Objectiveness viewed as lack of empathy.Expertise viewed as “Ivory Tower’ism”We are not good at saying we don’t know
28. In ConclusionCancer 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 clusterFrom exposure to diagnosis can be 20 – 50 years, depending on carcinogenMost prevalent cancers are not strictly caused by environmental exposures – i.e., lung or prostate cancerIgnorance: what we think is harmless today, tomorrow we may learn is dangerous.We must take responsibility and precautions to safeguard our health.
29. For More Information on Cancer ClustersACS: 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
30. Calculating Disease RiskHarvard School of Public Health, Disease Risk Profile: http://www.diseaseriskindex.harvard.edu/update/hccpquiz.pl?lang=english&func=home&page=cancer_index
31. Thank You!