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Cancer risk perceptions in an urban Mediterranean population
Version of Record online: 4 MAY 2005
Copyright © 2005 Wiley-Liss, Inc.
International Journal of Cancer
Volume 117, Issue 1, pages 132–136, 20 October 2005
How to Cite
García, M., Fernández, E., Borràs, J. M., Nieto, F. J., Schiaffino, A., Peris, M., Pérez, G., La Vecchia, C. and for the Cornellà Health Interview Survey Follow-Up (CHIS.FU) Study Group (2005), Cancer risk perceptions in an urban Mediterranean population. Int. J. Cancer, 117: 132–136. doi: 10.1002/ijc.21091
- Issue online: 2 AUG 2005
- Version of Record online: 4 MAY 2005
- Manuscript Accepted: 5 JAN 2005
- Manuscript Received: 21 OCT 2004
- Fondo de Investigación Sanitaria. Grant Number: PI02/0261
- Cornella de Llobregat City Council
- Instituto de Salud Carlos III, Network for Research in Epidemiology and Public Health (RCESP). Grant Number: C03/09
- Instituto de Salud Carlos III, Network for Research in Cancer (RTICC). Grant Number: C03/10
- risk perception;
- cancer prevention;
- health education
The objective of our study was to analyze the perceived (belief) or adopted (behavior) measures to reduce cancer risk in a Spanish population. We used cross-sectional data from the Cornella Health Interview Survey Follow-up Study (CHIS.FU). We analyzed 1,438 subjects who in 2002 answered questions about risk perceptions on cancer and related behavior (668 males and 770 females). The benefits of avoiding cigarette smoking (95.8%), sunlight exposure (94.9%) and alcohol (81.0%) were widely recognized. On the other hand, electromagnetic fields (92.1%), food coloring and other food additives (78.4%) or pesticides (69.4%), whose role in cancer occurrence, if any, remain unproven, were clearly considered as cancer risk factors in this population. Compared to men, women more frequently reported healthy behaviors, and the role of exogenous factors (i.e., environmental risk factors) were widely popular. There was a socioeconomic gradient on cancer risk perception with respect to several lifestyle or dietary factors. Individuals with higher educational level scored lower in several risk factors than those with primary or less than primary school education. Smokers reported adopting fewer healthy behaviors than former or never smokers. How people perceive health issues and risk or make choices about their own behavior does not always follow a predictable or rational pattern. © 2005 Wiley-Liss, Inc.
Individual cancer risk may be influenced by exogenous factors (i.e., environmental risk factors), by genetic factors (genetic susceptibility) or by the interplay between them.1 It has been stated that more than 50% of cancer could be prevented if our current knowledge of risk factors were successfully implemented to reduce risk factor prevalence.2 Most cancers in a population are also attributable to potentially modifiable environmental risk factors.3, 4 How these risks are perceived by the individuals could be related to the actual behavior, although evidence for such a relationship is weak.5 Cognitive psychology and neuroscience theories indicate there are 2 fundamental ways in which human beings comprehend risk: the “analytic system” uses algorithms and normative rules such as formal logic and risk assessment, while the “experiential system” is intuitive, mostly automatic and not very accessible to conscious awareness. Both systems operate in parallel and mutually depend on the other for guidance and, hence, rational decision making requires proper integration of both modes of thought.6
Research on public's perception of cancer can help to improve risk communication and health promotion strategies from the public health system. Thus, studies on cancer risk perception have focused in areas related to the value of screening procedures,7, 8, 9 in people who either have the disease or have a relative affected by the disease10, 11 or in ad hoc population samples.12 There is scarce information in Spain about the knowledge or concerns of the general public on the relative importance of various cancer risk factors.13 Thus, the aim of this study was to analyze the perceived (belief) or adopted (behavior) measures to reduce cancer risk in a Spanish population.
Material and methods
We used cross-sectional data from the Cornella Health Interview Survey Follow-Up (CHIS.FU) Study. The CHIS.FU study is a population-based cohort focusing on lifestyles and their consequences in health status. The cohort was set up with 2,500 subjects (1,263 women and 1,237 men) randomly selected from the general population of the city of Cornellà de Llobregat, located on the Metropolitan area of Barcelona, in Catalonia, Spain (http://www.cornellaweb.com). Cornellà de Llobregat is an industrial town of approximately 85,000 inhabitants, mainly working- and middle class, with an important migrant population (during the 1960s and 1970s) from other Spanish regions (mainly from the south). Subjects were initially interviewed in person in 1994.9, 10 In 2002, we attempted to contact again and interview by telephone the cohort members. A detailed description of the subject recruitment and procedures is provided elsewhere.15, 16 Briefly, we obtained a 64.3% response in the total of the cohort; thus, at follow-up we gathered information from 1,608 subjects. Of the remaining 35.7%, 147 individuals were deceased, 425 had emigrated, 123 refused the interview and 197 could not be located. Subjects aged <15 years (n = 93) and those with disabilities did not respond to the cancer risk assessment (n = 77) and hence we analyzed 1,438 subjects who answered in 2002 the questions about risk perceptions on cancer from the direct follow-up questionnaire (668 males and 770 females).
The questionnaire included a general section on perceived risk of cancer. Information was specifically collected on perception of risk (“Do you consider that…can prevent cancer?”) and related behavior (“How do you behave in relation to…?”) for 9 major recognized or potential risk factors for cancer, as investigated in a previous European survey.13, 17 For each factor, 3 replies were included in the questionnaire for belief (“yes,” “no,” “I do not know”) and 2 for behavior's adoption (“yes,” “no”). To evaluate potential obsequiousness bias,18 we also included a tricky item on ultraviolet radiation (UV) exposure (“Do you consider that increasing UV exposure can prevent cancer?”: “yes/no”).
Because of changes in the composition of the cohort since 1994 due to attrition during follow-up,19 the sample of respondents in 2002 overrepresented middle-aged men and women of the inception cohort. Consequently, comparison of baseline and follow-up data was carried out after sex- and age-standardization by the direct method, using the 2001 Cornella Census as the referent population. Specific analyses according to sex, educational level and smoking behavior were also performed.
Table I gives the percent population perceiving (belief) or adopting (behavior) selected measures to reduce cancer risk, ranked according to belief. Avoiding smoking ranked 1st according to belief (95.8%) but was only the 5th most reported behavior (70.6%). Overall, 94.9% of the respondents (ranked 2nd according to belief) considered that limiting exposure to sunlight was protective to prevent cancer but just 77.9% of them (ranked 2nd according to behavior) reported adopting such behavior.
|Limiting exposure to sunshine||2||94.9||2||77.9|
|Avoiding exposure to electromagnetic fields||3||92.1||7||64.0|
|Avoiding genetically modified food||4||82.3||6||65.4|
|Reducing alcohol drinking||5||81.0||1||95.4|
|Limiting consumption of food coloring and other additives||6||78.4||8||61.4|
|Avoiding excessive calorie intake||8||72.6||4||71.4|
|Avoiding pesticide-treated fruit and vegetables||9||69.4||9||35.5|
|Increasing exposure to UV||10||7.9||—||—|
The proportion of individuals who considered that avoiding exposure to electromagnetic fields (92.1%) and avoiding genetically modified food (82.3%) could prevent cancer was higher than those who declared that reducing alcohol drinking was a protective factor for cancer (81.0%). A smaller proportion believed in the preventive potential of selected nutritional and dietary factors, such as avoiding overweight (72.6%) or avoiding excess calorie intake (72.6%), ranking them 7th and 8th, respectively. However, the latter ranked 3rd and 4th according to behavior adopted by the participants. Most participants (78.4%) believed that limiting consumption of food coloring and other food additives was protective for neoplasms, which ranked higher than avoiding pesticide-treated fruit and vegetables (69.4%).
Table II describes the cancer risk beliefs and behavior according to sex. Males and females ranked perceived risks in the same order and the rank order of behaviors varied only slightly by gender. However, more women than men believed on the protective role of avoiding electromagnetic fields, food coloring and other food additives or pesticides; women also more frequently reported certain healthy behaviors (reducing alcohol drinking, limiting sunshine exposure, avoiding smoking and avoiding overweight) than men.
|Males n = 668||Females n = 770|
|Limiting exposure to sunshine||2||93.9||3||71.0||2||95.9||2||84.6|
|Avoiding exposure to electromagnetic fields||3||89.1||7||57.9||3||95.0||7||69.8|
|Avoiding genetically modified food||4||78.5||6||60.4||4||85.8||8||69.7|
|Reducing alcohol drinking||5||76.6||1||92.0||5||85.2||1||98.6|
|Limiting consumption of food coloring and other additives||6||73.7||8||52.0||6||82.7||6||69.9|
|Avoiding excessive caloric intake||8||68.3||5||62.6||8||76.9||3||79.8|
|Avoiding pesticide-treated fruit and vegetables||9||66.3||9||31.6||9||72.8||9||39.2|
|Increasing exposure to UV||10||9.1||—||—||10||6.5||—||—|
Table III shows the public's cancer risk perception and related behaviors according to educational level. A socioeconomic gradient on cancer risk perception is evident for several lifestyle or dietary factors. The proportion of individuals with college or university studies who considered that avoiding genetically modified food (77.7%) and limiting consumption of food coloring and other additives (72.3%) could prevent cancer was lower than among subjects with less than primary studies (91.3% and 85.7%, respectively). Individuals with higher educational level declared less frequently that avoiding overweight (70% vs. 84.8%) and avoiding excessive calorie intake (63.7% vs. 85.0%) could be effective in preventing cancer than subjects with less than primary studies. A similar pattern was apparent in both sexes (data not shown).
|Less than primary2||Primary studies||Secondary + University|
|n = 337||n = 695||n = 400|
|Limiting exposure to sunshine||2||93.3||2||82.8||2||94.0||2||75.5||2||97.0||3||78.5|
|Avoiding exposure to electromagnetic fields||3||93.2||5||75.4||3||92.2||7||67.4||3||91.3||7||54.0|
|Avoiding genetically modified food||4||91.3||6||74.5||4||82.9||5||68.1||5||77.7||6||57.1|
|Reducing alcohol drinking||7||84.9||1||96.4||5||80.8||1||95.1||4||79.1||1||95.3|
|Limiting consumption of food colouring and other additives||5||85.7||4||76.8||6||80.3||8||63.5||6||72.3||8||50.2|
|Avoiding excessive calorie intake||6||85.0||7||73.1||8||74.9||4||70.6||9||63.7||4||71.8|
|Avoiding pesticide-treated fruit and vegetables||9||71.4||9||42.3||9||67.2||9||39.0||7||71.2||9||27.1|
|Increasing exposure to UV||10||9.1||—||—||10||7.2||—||—||10||8.0||—||—|
Table IV shows the proportion of population perceiving or adopting selected measures to reduce cancer risk according to their smoking status. A lower proportion of smokers declared adopting potentially preventive behaviors than former and never smokers. Nevertheless, 95.7% of current smokers believed that avoiding smoking can prevent cancer. A lower proportion of smokers declared to avoiding exposure to sunlight (69.7%) than former (82.2%) and never smokers (81.0%). Reducing alcohol drinking was considered beneficial to prevent cancer by 77.4% of the smokers, in comparison with former (81.0%) and never smokers (83.0%). Moreover, fewer smokers considered the importance of avoiding overweight (73.6%) or avoiding excessive calorie intake (68.6%) to prevent cancer than former and never smokers.
|Never smoked2n = 796||Current smokers n = 379||Former smokers n = 262|
|Limiting exposure to sunshine||2||95.7||3||81.0||2||94.2||3||69.7||2||93.8||3||82.2|
|Avoiding exposure to electromagnetic fields||3||92.3||7||64.1||3||91.7||6||61.3||3||92.0||7||67.9|
|Avoiding genetically modified food||4||83.5||6||66.0||5||76.8||5||61.9||4||88.6||8||69.5|
|Reducing alcohol drinking||5||83.0||2||96.7||4||77.4||1||93.6||6||81.0||2||94.2|
|Limiting consumption of food coloring and other additives||6||80.5||8||63.4||7||71.1||7||51.9||5||84.0||6||71.0|
|Avoiding excessive caloric intake||8||74.0||5||75.1||8||68.6||4||64.4||8||75.4||5||71.9|
|Avoiding pesticide-treated fruit and vegetables||9||72.9||9||33.2||9||64.1||8||36.5||9||68.0||9||40.5|
|Increasing exposure to UV||10||7.6||—||—||10||9.3||—||—||10||6.3||—||—|
While avoiding smoking was reported as the major protective factor for cancer, it was not the most frequently adopted behavior. How people perceive health issues and risk and how they make choices about their own behavior do not always follow a rational pattern.20 However, we have to take into account that people may make choices that appear irrational based on strict statistical assessment. If a community has reason to distrust the public health and medical community, or government authorities who announce risk levels, members of the public may choose to ignore those announcements and may perceive risks in an apparently “irrational manner.” This risk perception, however, may be quite rational given the political history and social context. In essence, people do not know who or what to trust so they default to an apparently “irrational” high level of risk perception. The current “irrational” perception of risk associated with genetically modified foods, pesticides, food colorings and electromagnetic waves may be affected by mistrust of official pronouncements regarding their risk because of past experiences with changing official risk evaluations. In Spain, we have good examples such as the Toxic Oil Syndrome,21 the Prestige disaster22 and the accident at the oil refinery that have increased concern in the population about health effects of chemical substances.23
According to most theories regarding the adoption of health protective behaviors,24, 25, 26 perceptions of susceptibility to illness are necessary prerequisites. Thus, perceived cancer risk motivates the acceptance of screening for breast, cervical, and colorectal cancer.27, 28, 29 In relation to skin cancer, public campaigns to alert on the harmful effects of high and prolonged exposure to sunlight have been conducted in Spain during the last few years.
While reducing alcohol consumption was considered a protective factor by 81.0% (ranking in the 5th place) of the participants, a higher percentage was obtained when considered the behavior adopted (95.1%). Similar results regarding alcohol consumption but with a higher belief of the harm it causes have been described in other Mediterranean countries.13 This is likely related to other short term effects of alcohol drinking such as accidents and violence.
We detected several apparent misconceptions about cancer risk based on current scientific knowledge and standard statistical risk assessment. The importance of avoiding electromagnetic fields (whose role in cancer occurrence, if any, remains unproven),30, 31 was widely reported (92.1%). The role of food coloring and other additives or pesticides were also perceived as risk factors by the large majority of the individuals. Perhaps respondents are expressing their perception of hypothetical risk vs. actual risk. Moreover, media reports about health risk associated with electromagnetic fields or dietary additives may have contributed to raising fears in the public.
It appears that the characteristics of risk factors that trigger more alarm are the following: involuntary exposure, inescapable damage perceived as dreadful, as well as the availability bias (events are perceived to be more frequent if we can easily recall examples of them).32 Regarding risks associated with food, optimistic biases (people tend to believe they are less at risk from a given hazard compared to someone else with similar demographic characteristics) are much greater for lifestyle hazards than for those associated with the technologies involved in food production.33
Whereas overweight was a well known risk factor for a majority of the public (76.9%), it ranked below other risk factors such as electromagnetic fields or food coloring and other additives. This is probably because, even though most people are aware of the importance of overweight as a cardiovascular risk factor, its role in cancer is not as well known, despite its inclusion in the European Code Against Cancer.34
There were differences in the percentage of beliefs and behaviors according to sex, with females showing higher percentages than males in all cases. Women might be more concerned about potential risks due to the health care role they adopt to care their families.35 In our study, 30.4% of women were housewives and most of them belonged to the low-middle socioeconomic class. Moreover, women between 50 and 64 years old are almost universally screened for breast cancer. The coverage in Cornellà de Llobregat is almost completed.36 This periodical contact with the Health Care Services may facilitate more awareness of other potential cancer risk factors.
We have observed a socioeconomic gradient in several lifestyle and dietary factors on cancer risk perception. Social class structure is an important determinant of population health status. In Spain, socioeconomic inequalities in mortality and morbidity have been found, with the less privileged classes consistently showing higher rates.37 Education influences health through its relation with higher income and better living conditions, since well educated people are less likely to be unemployed and more likely to have jobs with higher salaries.38 Furthermore, the well educated have certain psychological resources, such as a strong sense of personal control and social support, in addition to economic resources, that are associated with higher health status.39 Moreover, living in a relatively deprived area can have a detrimental effect as an individual level of deprivation has been taken into account. Area level of deprivation may influence individual conduct directly through psychosocial mechanisms, determining convictions and attitudes, as well as limiting opportunities and resources for changing behavior.40
Smokers reported lower perceptions of risk about cancer and adopted less frequently health behaviors compared to former and never smokers. Since cigarette smoking causes more preventable deaths from cardiovascular disease and cancer than any other modifiable risk factor, physicians and public health professionals should educate smokers about their personal health risks as part of comprehensive efforts to promote smoking cessation.41 Moreover, it is important that smoking education campaigns and materials must present clear and accurate quantitative information about the health risks of smoking.42
We observe a low degree of agreement between certain beliefs and behaviors. This might be partially explained by the fact that some factors are addictive (i.e., smoking and alcohol). This could explain why people continue smoking and/or drinking despite knowing their harmful effects. Other factors, due to unknown exposures (i.e., electromagnetic fields or pesticide-treated fruits and vegetables) cannot be avoided. Finally, for factors that are more easily modifiable (i.e., exposure to sunlight or excessive calorie intake) we can act and protect our health if we are better informed.
Our findings were consistent with a study conducted in Spain in 1998 for the main risk factors (smoking, exposure to sunlight, alcohol).13 However, the risk perception of electromagnetic fields and genetically modified food is higher in our study, which could stem from its recent impact in the media. Avoiding overweight and an excessive calorie intake were perceived more frequently as protective factors in our study than in the previous one. It can be argued that the public in 2002 had more information than 5 years earlier, due to public debates regarding the Mediterranean diet and its changes in the preferences of people.43, 44
We assessed the risk of cancer in general rather than specific types of cancer, so a certain degree of misclassification may account for some of the findings. The study sample was large enough to provide reliable estimates, but was not completely representative of the study base. Regarding reporting bias in the form of obsequiousness bias,18 so participants giving answers in the direction they perceive are of interest to the researchers, most of respondents (92.1%) correctly answered that UV exposure was a risk for cancer. Since Cornellà de Llobregat is an industrial city in the metropolitan area of Barcelona, with a low-middle socioeconomic status, these characteristics have to be considered when judging the external validity of these estimates.
As a limitation of this study, we do not know the perceived level of risk implied by a “yes” response. Several factors can affect the response on cancer risk perception using questionnaires, such as the use of single items or numerical scores, or the item order itself.45, 46 The widespread popularity of some beliefs and behaviors do not necessarily translate into “overestimates” of risk because the questions were categorical: “yes/no.” Thus, without knowing the perceived level of risk, it is not possible to state these are overestimates. Some respondents may have correctly perceived that some risks were probably low but because they are unknown, they may still be present and hence a “yes” response that they should be avoided. In essence, it is not possible to translate a high frequency of yes response into a high magnitude of perceived risk.
In Spain, it would be a more efficient use of public health resources to advocate broad changes in behavior to prevent cancer47 rather than to address the disease outcomes.
Influential organizations should develop methods of risk communication that address these apparent “irrational” perceptions with cogent explanations of actual statistical risk (and the limitations of current science). Moreover, the implications for using risk-communication approaches based on communicating scientific uncertainty should be widely discussed and analyzed.
In addition to this specific type of surveys, further research to advance our knowledge of cancer risk perception is needed. For instance, investigating the best way to inform or communicate the level of cancer risk associated with particular exposures to the public,20 taking into account the context of health behaviors in our country; investigating the characteristics associated with “rational” risk perception according to current scientific knowledge of cancer causes; or investigating the profile of subjects with dissonant behaviors and beliefs on cancer risk.
E.F., M.G. and A.S. conceived the CHIS.FU study. All the researchers of the CHIS.FU Study Group designed the final study protocol. M.G. and A.S. coordinated the field work, created databases and checked all data. M.G. performed statistical analysis for this article. M.G. and E.F. drafted the manuscript. C.L.V., J.M.B., F.J.N., G.P. and M.P. gave expert advice and made written contributions to subsequent versions of the manuscript. All the authors approved the final version of the paper. E.F. is the guarantor of the study.
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