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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; 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 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 Officer Workplace management Step Six: Perform Assessment Define geographic area by census tract Review observed cases Generate 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 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. 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. 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!
