The general public’s information needs and perceptions regarding hereditary cancer: an application of the Integrated Change Model
Introduction
For many years, efforts in public health regarding cancer prevention have focussed on determinants perceived as originating outside the body, such as smoking, inactivity or poor dietary habits [1]. Although lifestyle habits will continue to be important risk factors for cancer, the discovery of several cancer genes [2] and related technology for testing demand that health educators incorporate genetic information more fully into their preventive public health approach. At present the percentage of hereditary cancer is assumed to lie between 5 and 10% [3], [4]. Clinical cancer genetic research has identified a variety of hereditary cancer susceptibility syndromes [5]; hence, public health agencies are faced with the task of communicating the role of genetic information in disease prevention to a variety of audiences. However, at the moment, it is not clear what needs the general public has with respect to education, because these studies are lacking. On the one hand, it is conceivable that people may be willing to be informed as optimally and elaborately as possible, thus allowing a person to act upon this knowledge, thereby reducing potential danger. On the other hand, people may not feel capable of taking any relevant action against a cancer gene threat and thus may respond by denying the information and/or their risks and may develop feelings of fear.
Information has been gathered on patient perceptions of genetic predisposition [6], [7] and the impact of genetic counselling among those with an increased risk [8], [9], [10], [11], [12], [13]. For instance, Andrykowski et al. found that 53% of their respondents thought that their knowledge of genetics was good, but only 27% knew that both parents are important in assessing genetic breast cancer risks. Bluman et al. made similar findings [21]. Donovan and Tucker found increased knowledge about breast cancer to be related to the understanding of genetic breast cancer [15]. Chapple et al. concluded that people had less understanding in accepting genetic predisposition as a cause of cancer than risky life styles [22]. Furthermore, many studies showed that people overestimated their risk from hereditary cancer [7], [8], [11], [14], [15], [16], [17], [18], [19], [20]. However, the studies mentioned above targeted specific patient populations and did not analyse the general public’s need for more or less information on genetic cancer. Some studies were carried out among high risk populations [8], [11], [16], [17], [18], [21], [22], [23], [24] and many were also aimed at one particular cancer type [8], [11], [15], [17], [18], [20], [21], [23], [24]. In conclusion, awareness about the role of heredity predisposition has developed in these particular patient or risk groups, but this consciousness can lead to overestimating the impact of hereditary factors as causal factors for developing cancer. Finally, it remains unclear whether the general public has a need for more information on the role of genetics for cancer risks, what determines the existence or absence of such a need, and what the consequences need to be for cancer prevention. The scarcity of this type of knowledge also limits the potential of national cancer organisations to fine-tune their health education messages with respect to hereditary cancer.
The goal of this study is to explore the general public’s perception and needs with regard to their knowledge on genetics and cancer. In addition to describing the results for the total population, we assessed gender, age and educational differences. First, we will describe the study participants’ knowledge on genetics in relation to the development of cancer and their need for information on hereditary cancer. Second, risk perceptions with regard to several types of cancer are outlined. Third, the preferred topics and channels of information on heredity and cancer, as indicated by the participants, will be described. Fourth, attitudes, social influences, and self-efficacy expectations of the participants regarding towards their interest to receive information on hereditary cancer are depicted.
We used an Integrated Change Model (the I-Change Model), derived from the attitude–social influence–self-efficacy model, that can be considered as an integration of ideas of Ajzen’s Theory of Planned Behaviour [25], Bandura’s Social Cognitive Theory [26] and Prochaska’s Transtheoretical Model [27], the Health Belief Model [28], and Implementation and Goal setting theories [29], [30], [31]. Previous versions of this model (referred to as the ASE-model) have been used to explain a variety of types of health behaviour [32]. The most recent version, referred to as the Integrated Change Model [33] (Fig. 1) states that covert and overt behaviours are determined by a person’s motivation or intention to carry out a particular type of behaviour. Behaviour is the result of a person’s intentions and abilities. Intentions can range from not contemplating behavioural change to contemplating to change the behaviour very rapidly, e.g. within a month. A person’s abilities, such as being able to plan specific actions to reach the goal behaviour and intentions to implement these actions as well as actual skills, increase the chances of changing intentions into actions, while physical barriers can lower these chances. Three main types of factors determine a person’s motivation: attitudes, social influences, and self-efficacy expectations. A person’s attitude consists of the perceived cognitive and emotional advantages and disadvantages of the behaviour, including beliefs that a specific type of behaviour can contribute to a lowered risk of developing a disease, also referred to as response efficacy in the Protection Motivation Theory [34]. Social influences consist of the perception of others carrying out this type of behaviour (social modelling), the norms that people have with respect to these behaviours (social norms) and the support that they encounter from others in carrying out a particular type of behaviour [35]. Self-efficacy refers to a person’s perception of his capability to carry out the type of behaviour [36], [37]. Recent studies showed that different types of self-efficacy may exist, such as social-, stress-, skills- and routine self-efficacy [38], [39], [40]. Furthermore, the Integrated Change Model assumes these motivational factors are determined by various distal factors such as awareness factors (e.g. knowledge, risk perceptions and cues to action) [28], predisposing factors such as behavioural factors (e.g. life styles), psychological factors (e.g. personality), biological factors (e.g. gender, genetic predisposition), social and cultural factors (e.g. the price of cigarettes, policies), and information factors (the quality of messages, channels and sources used) [32], [33].
Section snippets
Recruitment
Since awareness of hereditary predisposition for specific types of cancer is particularly important for younger adults, we decided to focus on this age group. Consequently, the target population was comprised of adults between 18 and 50 years of age who were not undergoing treatment for cancer.
A random sample of 4000 persons was generated from the address file of the Dutch Telecom Company. This sample was approached for participation in our study. Each person received an invitational letter
Characteristics of the sample
Of the 4000 participants, 478 people in the age group of 18–50 years returned the questionnaire within 3 weeks, a response of approximately 24% of the estimated eligible population. Twenty-one respondents had more than 10% missing values on questions, and were excluded from the study [42], thus reducing the total sample to 457.
The sample consisted of 257 (56%) women and 200 (44%) men. The mean age of the respondents was 36.5 years (S.D. 8.3 years). The majority of the respondents (72%; N=329)
Discussion and conclusions
Significant advances in molecular genetic technology have been accomplished. It is expected that most, if not all, human genes will be mapped and sequenced [44], [45], [46]. This emergence of genetic technology is accompanied by increasing concern regarding the use or misuse of genetic information in society [47], [48], [49], [50], and by unrealistic expectations regarding the role of genetic factors in the onset and development of cancer. The contribution of hereditary cancer is modest and
Acknowledgements
This study was supported by a grant from the Dutch Cancer Society. We thank Heidi Arendsen for her help with data collection and analysis, Alexandra Dummert for her help in preparing this paper, Laura McCormick and the reviewers for their comments and suggestions.
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