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Colorectal cancer screening: Yes or No?

Douma, L.N.

2019

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Douma, L. N. (2019). Colorectal cancer screening: Yes or No? Insights into public opinion and the individual decision-making process.

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535373-L-bw-Douma 535373-L-bw-Douma 535373-L-bw-Douma 535373-L-bw-Douma Processed on: 8-10-2019 Processed on: 8-10-2019 Processed on: 8-10-2019

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CHAPTER 1

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1. Introduction

Colorectal cancer (CRC) is one of the most common causes of cancer death in developed countries (1, 2). In the Netherlands, it currently ranks as the third most prevalent cancer among both men and women (2). Population-based CRC screening is widely recommended (3-6) as it can reduce the incidence and mortality of CRC (7-10). CRC screening involves possible benefits, but it also involves possible downsides, such as false positives, false negatives, overdiagnosis, overtreatment and risks associated with sigmoidoscopy/colonoscopy (5, 6, 11-14). Whether the possible benefits for an individual outweigh the possible downsides depends on how that individual perceives and values the possible benefits, harms and risks of CRC screening (15-17). Therefore, experts in the field of cancer screening increasingly consider it important that people make a personal and informed decision concerning CRC screening participation (18, 19).

The main objective of this thesis was to gain more insight into the individual decision-making process regarding CRC screening as well as into the societal context (i.e. public opinion) within which this decision is being made. Subsequently, these insights could be used to further develop support to people when they make their CRC screening decision and optimise their decision-making process.

Preventive cancer screening

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which contributed to the general approval and uptake into clinical practice. Gradually, large-scale preventive screening began to take form, especially in the second half of the 20th century (23, 24). Subsequently, in 1968, Wilson and Jungner (25) published 10 fundamental principles, which are still being used, intended to guide institutions in deciding about whether a population-based screening test should be introduced. Generally, population-based screening should be aimed at an important health problem, which can be identified at an early stage and for which treatment is more effective at an earlier stage. Additionally, a suitable test or examination that is acceptable to the public should be available and the cost-effectiveness should be considered. Currently, screening for several types of cancer is available in most western countries, the most prevailing being for breast, cervical and colorectal cancer (26-28). In some countries, cancer screening is organised at the national level, such as in the Netherlands, the United Kingdom (UK) or Australia, or at the regional, state or provincial levels, such as in Italy (29, 30). With organised cancer screening, people are actively invited to participate in cancer screening and the uptake is monitored. However, other countries, such as Germany or the United States of America (USA), rely on opportunistic screening (31, 32), where, in essence, the responsibility lies with the individuals themselves to ask their physician to be screened, and the uptake may not be monitored. Nonetheless, in the case of opportunistic screening, a national guideline covering recommendations concerning cancer screening often does exist (32).

Public opinion and existing views

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public that it was a good thing to do and that they should participate in it (11, 19, 24, 33, 34). Understandably, this was not a hard message to sell as, similar to medical professionals, the idea that identifying cancer early on is good makes sense and appeals to the public as well. Because of this long-held ‘benefit-focused’ communication strategy, it is likely that among the general public there is a preconceived notion, or social norm, that participating in cancer/CRC screening is something positive. As people make their decision concerning CRC screening participation within a social/societal context, it is plausible that this public notion or opinion affects people’s personal views and attitude towards CRC screening and, consequently, their personal decision concerning participation (35-38).

Another aspect to consider is the possible influence of pre-existing notions or views about more general concepts related to CRC screening, such as cancer and preventive screening in general, which the public are likely to have based on previous experiences and knowledge. These pre-existing views could provide the public with a ‘mental framework’, which can be used as a ‘short-cut’ to help understand and evaluate the less familiar and more specific subject of CRC screening by acting as a guide concerning which information is used and how to interpret it (39-43). For example, having pre-existing views of cancer being a serious disease and preventive screening being something positive could help in assessing that colorectal cancer in particular is also a serious disease, and that CRC screening is also something positive. However, as information that fits well with people’s pre-existing notions or views is generally noticed more often and valued more highly, this framework could also possibly affect how well-informed the public become about CRC screening (39-41, 43-45). Pre-existing views of cancer being a serious disease and preventive screening being something positive, for example, could then lead to people noticing and valuing information about the benefits of CRC screening more than information about the harms and risk of CRC screening.

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knowledge on the opinion and views of the general public concerning CRC screening, as the majority of studies on CRC screening (as well as other cancer screenings) have focused on examining the views of only the eligible CRC screening population within the direct context of individual participation (46-52).

Autonomous and informed decision-making

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A deliberative decision based on sufficient and relevant knowledge concerning the different choice-options (i.e. fully informed) and consistent with the decision-maker’s values, often operationalised as their attitude towards screening and/or their preferences towards a screening test (18, 61, 62). A central part of an informed decision is also that it is one’s personal and free decision (i.e. autonomous decision).

In the context of cancer screening and CRC screening, both informed and shared decision-making can be encountered. It is important to note that these two concepts are not equivalent to each other. In informed decision-making, it may be that no one else other than the individual it concerns is actively involved in the decision-making process, which is the situation in the Netherlands. It can also be that a physician is merely involved to provide information about screening. In both cases, there is no active, bidirectional discussion between a physician and the decision-maker about the screening information and the decision-maker’s values and preferences. Additionally, individuals are responsible for their own decision. In shared decision-making, however, an active, bidirectional discussion between a physician and the decision-maker is present and the final decision is made jointly. This process could stimulate a broader perspective on the information, values and preferences involved (58, 63).

CRC screening participation

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makes decisions in practice and when they consider they have made an informed and ‘good’ screening decision.

Another main focus of previous research on CRC screening seems to have been to examine which reasons and factors were associated with screening uptake or participation (66, 67). Research on CRC screening participation has often used the Health Belief Model (HBM) (66) or the Theory of Planned Behaviour (TPB) (52) as a framework. Within HBM and TPB, the emphasis lies on assessing people’s beliefs, knowledge, perceived social norm, self-efficacy, and practical barriers, which have all been shown to be associated with people’s decisions concerning CRC screening participation (52, 66, 68, 69). Some studies also found that people’s experiences, intuition, feelings, and social support were associated with their decision of whether to participate in CRC screening or not (16, 66, 69-71). Although these previous studies on CRC screening provide useful insights into why people do or do not participate in CRC screening, it appears that research on particularly the process of decision-making, and factors affecting this, could be expanded on.

Decision-making process

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more informed and thoughtful process (76, 77), or a ‘need-for-closure’, which would promote a more speedy process (78, 79). It can also be context-dependent. For example, a new or more complex decision often invokes a more thoughtful process, while time constraints can stimulate the use of intuition and heuristics as well as being influenced by other people’s behaviour (74, 80, 81). Furthermore, people’s motivation and goals are involved (regarding both their health and the accuracy of their decision). People who, for instance, experience a personal relevance, will be held accountable, or have a reason to be accurate will be more inclined to make an analytical and well-considered decision (74, 80-82). Additionally, people can have specific goals they want to achieve when making health-related decisions, such as becoming healthy or avoiding getting ill, which has been shown to influence their decision and decision-making process (74, 83-89). People’s goals and their orientation or focus surrounding it could affect how they interpret, use and value information concerning CRC screening (42, 88, 90, 91). In this way, people’s goal-orientation/focus could perhaps be seen as a general orientation affecting the relevance of people’s more specific beliefs and considerations concerning CRC screening. Examining people’s decision-making style and goal-orientation/focus regarding CRC screening could provide useful insights for a better understanding of people’s CRC screening decision-making process. However, to our knowledge, these two aspects have received little attention so far in the context of CRC screening, or other cancer screenings.

Possible differences associated with sociodemographics

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decision or to leave it up to others (98). Additionally, people with a lower education or low health literacy have potentially more difficulty with processing complex and large amounts of information as part of their decision-making process (95, 96). Considering these previous findings in the field of CRC screening and decision-making, it is possible that among the eligible CRC screening population there are different subgroups of people related to these sociodemographic characteristics, who might need different means of support in making an informed CRC screening decision.

CRC screening procedure

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Figure 1. CRC screening procedure in the Netherlands

Using a stool test as initial screening test, followed potentially by a colonoscopy, is also the approach of screening programmes in some other countries, for instance Australia (103). However, other approaches are also possible. For example, in the United Kingdom people aged 60-75 are offered a stool-test as initial test, while people aged 55-60 are offered a sigmoidoscopy as initial test (which is an internal examination of only part of the colon) (104). Furthermore, in countries that rely on opportunistic screening, such as Germany (31) or the United States (32), people have to decide themselves which screening test they prefer, having to choose mostly between a stool test, sigmoidoscopy or colonoscopy.

2. Objective and overview of this thesis

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making their CRC screening decision and optimise their decision-making process. Specifically, we focused on examining the following main aspects: 1) Public opinion concerning the Dutch CRC screening programme and related public perceptions; 2) People’s focus and decision-making style regarding the CRC screening decision; and 3) The concepts of autonomous and informed making in relation to decision-making in real life. Additionally (4), in a few of the studies we conducted, we examined possible differences associated with people’s sex, age, education and/or health literacy.

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