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A community based study on intentions regarding predictive testing for hereditary breast cancer
  1. M Welkenhuysen,
  2. G Evers-Kiebooms,
  3. M Decruyenaere,
  4. E Claes,
  5. L Denayer
  1. Psychosocial Genetics Unit, Centre for Human Genetics, Herestraat 49, 3000 Leuven, Belgium
  1. Professor Evers-Kiebooms, Gerry.Kiebooms{at}med.kuleuven.ac.be

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Editor—The recent developments in human genetics have led to the availability of predictive DNA tests for the hereditary subgroups of some cancers. During the past five years, genetic testing for mutations in theBRCA1 1 andBRCA2 genes,2 predisposing to hereditary breast/ovarian cancer (HBOC), has entered clinical practice. Several genetic centres/hospitals offer predictive testing for HBOC to women with a family history of the disease. Women who carry a HBOC mutation might decide on regular breast screening to increase the chances of early detection of the disease. Alternatively, they might opt for prophylactic surgery to reduce their breast/ovarian cancer risk as much as possible. In addition to the uncertainties involved in these management options, the ambiguity because of the incomplete and variable penetrance of the BRCA1/BRCA2mutations has to be dealt with as well3-5; recent estimations of the cumulative breast cancer risk for femaleBRCA1/BRCA2 mutation carriers vary between 50% and 85%. Alternatively, the absence of aBRCA1/BRCA2 mutation in affected family members does not eliminate the risk of developing breast cancer. It merely reduces the risk to the risk level in the general population, which is about 10% in the industrialised world.6 7Despite these uncertainties, the high frequency of breast cancer in the population may trigger questions about and interest in the predictive test for breast cancer. Also, media attention may play an important role by creating high hopes,8 as well as an increased awareness or misconceptions of the personal and population risk for breast cancer.9 10 Commercial companies may try to encourage testing for BRCA1/BRCA2 mutations by selling tests directly to physicians and/or the public.11 On the other hand, public concern, pessimism, or fear about the new genetic technology12 may discourage interest in applications like predictive genetic testing for HBOC, although such a negative effect regarding medical interventions has not been observed.

Most studies among first degree or more distant relatives of breast/ovarian cancer patients report high levels of interest (between 80% and 95%) in predictive testing for HBOC.13-20 The interest of women without a family history of breast cancer is usually less pronounced, although it is still quite high (ranging from 45% to 90%, but mostly between 60% and 75%10 21-27). This lower level of interest is in line with the positive relationship between the extent of the family history and the level of interest observed in a number of studies.21 24 28-30 Examples of other possible correlates of the interest in predictive testing for HBOC that have been investigated in the above mentioned studies are sociodemographic variables like education and age, emotional variables like cancer worry and depression, awareness measures, and control related variables like the belief that breast cancer is curable and that regular mammograms give a feeling of control, as well as control related personality and coping styles. Several studies paid attention to one or more components of the Health Belief Model31 to explain intentions or interest regarding predictive testing for HBOC. According to the Health Belief Model, a specific health behaviour is influenced by (1) the perceived susceptibility to or the perceived risk of the health threat, (2) the perceived severity of the health threat, (3) the perceived benefits of engaging in the health behaviour, and (4) the perceived costs of or barriers to performing the health behaviour. The Health Belief Model predicts that the higher the perceived susceptibility to and the perceived severity of a health threat, the more a person will engage in health behaviour. With regard to the benefits and the costs components, the Health Belief Model argues that people who perceive more benefits are more motivated to perform the health behaviour, while the reverse is true for people who perceive more costs. The perceived risk component has been studied frequently,13 15 19 20 23-25 28 32 33 as well as the perceived benefits and costs of having a predictive test for HBOC or reasons for and against having such a test.14 18 20 25-28 32 33 However, the perceived seriousness of hereditary breast cancer has (almost) never been included as a possible determinant of interest in a predictive test for HBOC.

The aim of the present study is twofold: first, to investigate the intentions to have a predictive test for hereditary breast cancer (HBC) among Flemish women from the general population who were not selected for a family history of breast cancer or for breast related health problems; secondly, to examine which factors influenced the reported interest in this unselected group, with special attention to the four components of the Health Belief Model, as well as a general attitudinal variable concerning the development of a predictive genetic test for HBC. The latter factor was included since the public perception of the applications of the new genetic technology may be an important mediator of personal intentions.

Methods

PROCEDURE

The participants in our study were students at the Institute for Family Sciences, a Flemish adult education institute in Brussels providing a three year programme with courses on family relations, psychology, health, and social care. During their lunch break, they were asked to complete a questionnaire on perceptions of breast cancer in general, as well as on sociodemographic and background variables (Questionnaire 134). After handing in the questionnaire, the students received a text with information on hereditary breast cancer (HBC), its mode of inheritance, the associated risks, the possibilities and limitations of the predictive test for HBC as well as on the management options (four pages). The following problems involving the predictive test for HBC were addressed: the incomplete penetrance of the HBC mutations, the genetic heterogeneity of breast cancer, the possibility of an inconclusive test result, the fact that non-carriers of a HBC mutation can still get breast cancer, and the residual breast cancer risk after prophylactic mastectomy. The text was accompanied by a questionnaire (Questionnaire 2) which the students were invited to complete and return. Ovarian cancer was not dealt with in the text or the questionnaire. Should the survey have elicited questions or problems involving breast cancer, the opportunity was provided to consult the researcher (MW or MD, psychologists).

MEASUREMENTS

The following sample characteristics were measured in Questionnaire 1 by multiple choice or open ended questions: gender, age, marital status, number of children, and level of education. Additionally, we asked whether breast cancer had occurred in the family and, if so, which family member(s) (had) suffered from the disease (open ended questions). The remaining questions were all included in Questionnaire 2.

The dependent variable in our study was the personal intention to have a predictive test for HBC. This was measured by a multiple choice question (“In case breast cancer occurs in your family, would you ask for a predictive genetic test to determine if you carry a breast cancer mutation?”) with four response alternatives (definitely not, probably not, probably, definitely). The participants were invited to explain their answer (open ended question). For the analysis of the relationship with other variables, the intention to have a predictive test for HBC was recoded as a dichotomous variable. The “definitely not” and “probably not” answers were collapsed into a single category of negative intentions or uninterest; the “probably” and “definitely” answers were grouped into a single category of positive intentions or interest. The independent variables were the following.

(1) The participants' awareness of the subject of our study; this was checked by means of the following questions: “Had you heard about hereditary breast cancer before reading the text?”, “Had you heard about the predictive genetic test for hereditary breast cancer before reading the text?”, “Have you ever asked a medical doctor for information about hereditary breast cancer and/or the predictive test?” (yes/no answers). The sum of positive answers was the awareness score.

(2) The general attitude towards the development of a predictive test for HBC: this was assessed by four bipolar five point rating scales, with scores ranging from 1 to 5. Higher scores corresponded to a more positive attitude. The following pairs of adjectives were used: important/unimportant, acceptable/unacceptable, needless/essential, good for humanity/bad for humanity. The internal consistency among the four scales was good (Cronbach α=0.88). The sum of the four individual scale scores divided by the number of scale items represented the general attitude score. When one (or more) of the individual scale scores was missing, the general attitude score was not calculated.

(3) The components of the Health Belief Model. (A) The measurement of the susceptibility and seriousness components was based on two breast cancer specific instruments designed by Champion35 for her research on the Health Belief Model. The instruments consist of six and 12 statements respectively with which one can agree or disagree on a five point Likert scale, for example, “I am likely to get breast cancer in the future” for the perceived susceptibility scale, and “I am afraid to even think about breast cancer” for the perceived seriousness scale. We adapted these by replacing the term “breast cancer” in the statements by the term “hereditary breast cancer”. The internal consistency of the resulting scales was good (Cronbach α=0.79 and 0.86, respectively). The perceived susceptibility and the perceived seriousness score for HBC were obtained by dividing the sum of the individual item scores by the number of scale items. Higher scores indicated a stronger feeling of being susceptible to HBC and a perception of the disease being more serious. (B) The benefits and barriers components were assessed through a combination of items adapted from research on attitudes toward predictive testing for Huntington's disease36 and items especially designed for the present study. The assessment consisted of importance ratings on seven point scales (1 = not important, 7 = very important) of arguments for and against predictive testing for HBC. A factor analysis yielded a two factor solution: the benefits subscale (eight items, Cronbach α=0.87) and the barriers subscale (eight items, Cronbach α = 0.80).

STATISTICAL ANALYSIS

For the analysis of univariate associations between variables, chi square tests and Pearson correlational analysis were used when categorical or continuous measures were involved, respectively. To compare mean scale scores, t tests were used. For the multivariate analysis of the relationship between the dependent variable and the set of sociodemographic variables and independent variables, stepwise logistic regression was performed. For all the statistical analyses, the SAS System software was used.

SAMPLE

Since the proportion of male participants was small (about 10%), only the results of the female participants were included in the analyses. About 70% (n=332) of the 471 women who filled in Questionnaire 1 and who subsequently received the informative text as well as the questionnaire on HBC and the predictive test returned a completed questionnaire (Questionnaire 2). After exclusion of three women who have or have had cancer, the sample consisted of 329 women between 19 and 65 years old (mean age=37.9 years). Most of them were married (69%), 15% had a partner, 8% were single, and the remainder were divorced (7%) or widowed (1%). The majority had children (85%, the mean number of children was 2.2). Before starting the programme at the Institute for Family Sciences, a minority of the sample (4%) had obtained a university degree, 34% had completed another type of higher education, 36% had had a general education in secondary school, 18% had had a technical education, and the remaining 8% had had a vocational training. Twenty-one percent of the sample (n=68) reported that breast cancer (had) occurred in the family.

Results

DESCRIPTIVE DATA FOR THE TOTAL SAMPLE

Table 1 presents the data for the dependent variable and most independent variables for the total sample. The intentions to have a predictive test for HBC were mainly positive. Awareness of HBC was moderate, but only one fifth of the sample had heard about the predictive test for HBC and less than 10% had asked a medical doctor for information about these issues. As expected, the latter was more likely when breast cancer occurred in the family (χ2=22.40, p<0.01). The results of the three questions added up to the following awareness scores: 21% answered no to all three questions and got score 0; 57% answered yes to one question and obtained score 1; 19% obtained score 2 (two affirmative answers); 3% answered yes to all three questions and got score 3. The general attitude toward the development of a predictive test for HBC was favourable; the mean ratings for each of the four items were high, resulting in a mean general attitude score of 4.3. The mean perceived susceptibility score and the mean perceived seriousness score in our unselected sample were low to moderate. The mean importance ratings for the individual arguments for and against predictive testing for HBC are shown in table 2. The means for the benefits and the barriers subscales were 4.9 (SD=1.30) and 3.4 (SD=1.21), respectively. At test showed that the mean for the arguments in favour of testing was significantly higher than the mean for the arguments against (t=12.74, p<0.001).

Table 1

Intention to have a predictive test for HBC, awareness of HBC and the predictive test, general attitude toward the development of a predictive test for HBC, perceived susceptibility to HBC, and perceived seriousness of HBC

Table 2

Mean importance ratings of the arguments for and against having a predictive test for HBC (7 point scales; the arguments are listed according to the mean rating of importance)

VARIABLES ASSOCIATED WITH THE INTENTION TO HAVE A PREDICTIVE TEST FOR HBC IN THE TOTAL SAMPLE

Table 3 shows the univariate Pearson intercorrelations in the total sample between the dichotomised intention and the sociodemographic and independent variables. A chi-square test indicated that the dichotomised intention to have a predictive test for HBC was not associated with marital status (χ2=4.45, p=0.62). To identify factors having an independent association with the intention regarding the predictive test for HBC, a multivariate stepwise logistic regression analysis was performed, modelling uninterest. The results of the logistic regression in table 4 show that the perceived susceptibility score, which had an unexpected negative univariate association with the dichotomised intention (table 3), was not retained as a predictor in the regression. The benefits score was the first to enter the logistic regression with an odds ratio of 0.34. This means that when the benefits score increased by one unit, the odds to report a negative intention regarding the predictive test for HBC decreased by a factor of 0.34. Similarly, the odds ratio of 0.52 for the general attitude score indicates that with each increase in the attitude score, the odds to express uninterest decreased by a factor of 0.52. In other words, women who rated the arguments for a predictive test for HBC as more important (the benefits score) and women with a more positive attitude toward the development of such a test (the general attitude score) were less likely to report uninterest in the test. Higher odds of a negative intention were associated with a higher number of children and with the occurrence of breast cancer in the family. The value for the latter variable was quite high; the women in our sample who have (had) a relative with breast cancer had 3.61 higher odds of being uninterested in the predictive test for HBC than the women without a relative with the disease. The observation that women with breast cancer in their family were more doubtful about the predictive test is an unexpected and intriguing finding which was analysed further.

Table 3

Intercorrelations (r; Pearson coefficients) between the intention to have a predictive test for HBC (dichotomised variable), the sociodemographic variables, and the independent variables. The significant relations are in bold; the corresponding p values are indicated below the table

Table 4

Stepwise logistic regression of the intention to have a predictive test for HBC (dichotomised variable; the analysis models negative intentions; n=254)

EXPLORING THE INFLUENCE OF THE OCCURRENCE OF BREAST CANCER IN THE FAMILY ON THE INTENTION TO HAVE THE PREDICTIVE TEST FOR HBC

To explore the influence of the occurrence of breast cancer in the family on the intention to have the predictive test for HBC, the sample was divided into two subgroups: a subgroup of women who have (had) at least one relative with breast cancer (the BC group, n=68) and a subgroup of women who have (had) no relatives with the disease (the No BC group, n=261). The results for the intention to have a predictive test for HBC for the separate subgroups are shown in table 5. Uninterest in a predictive test for HBC was observed much more often in the BC group (66% versus 25% in the No BC group, χ2=40.72, p=0.001). The spontaneous explanations for the reported intention that were given most frequently in both subgroups are also shown in table 5. The explanations involving preventive measures, knowledge, or certainty were more likely to be given by the No BC group, whereas the BC group was more inclined to use explanations referring to emotions like anxiety or to the emotional burden of being a carrier. Further, the following significant relationships with the occurrence of breast cancer in the family were observed (table 3, fifth row): the BC group was more aware of HBC and the predictive test and had a more negative attitude towards the development of such a test than the No BC group (the mean awareness scores were 1.3 and 1.0 respectively; the mean general attitude scores were 4.0 and 4.4 respectively), they perceived themselves as more susceptible to HBC (the mean susceptibility scores were 2.4 and 1.4 respectively), and they rated the arguments for having a predictive test for HBC as less important than the No BC group (the mean benefits scores are 4.1 and 5.1 respectively). The mean importance ratings of the arguments against were the same in the two subgroups (3.7 and 3.4 respectively). Subsequent within subgroup comparisons of the mean importance ratings show that the arguments for the predictive test were judged as more important than the arguments against in the No BC group (5.1>3.4, t=14.24, p<0.0001), while there was no difference in the BC group (4.1 and 3.7, t=1.54, p=0.13).

Table 5

Intention to have a predictive test for HBC: results for the group of women with breast cancer in the family (the BC group, n=68) versus the group of women without breast cancer in the family (No BC group, n=261)

Separate stepwise logistic regression analyses explored whether the set of variables explaining a negative intention differed between the BC group and the No BC group. The results of these analyses are presented in table 6. In both subsamples, the benefits score was the first variable to enter the logistic regression; with each increase in the benefits score, the odds to express uninterest decreased by a factor of 0.40 in the No BC group and by a factor of 0.07 in the BC group, indicating that the explanatory value of the benefits score was higher in the No BC group. Age entered as an additional explanatory variable in the BC group; for each increase in age by one year, the odds to report a negative intention increased by a factor of 1.20. In the No BC group, the general attitude score and the number of children had an additional explanatory value; women without relatives with breast cancer were less likely to report uninterest in the predictive test for HBC when they had a more positive attitude towards the development of such a test, while they were more likely to report uninterest when they had more children.

Table 6

Stepwise logistic regression of the intention to have a predictive test for HBC (dichotomised variable; the analysis models negative intentions) in the group of women with breast cancer in the family (n=51) and the group of women without breast cancer in the family (n=203)

Discussion

At first glance, our results confirm the strong interest in the predictive test for HBC found in most other studies. In the present study, the general level of interest was higher than the level observed in a study on the predictive test for Huntington's disease among a comparable community sample,37 in which about half the women expressed interest in the predictive test for this neurogenetic disease. This is not surprising given the crucial differences between breast cancer and Huntington's disease, for instance regarding the familiarity with the disorder and the possibilities for risk reduction and treatment. Also consistent with previous research,20 32 our sample considered the benefits of the predictive test for HBC on the whole as more important than its costs, and the possibilities of decreasing the breast cancer risk and to learn about one's children's risk were valuable arguments for testing. However, the contrast between women with versus without breast cancer in the family (the BC group versus the No BC group) forces a shift from this general level of discussion to a more specific one. The women in our sample who are related to a breast cancer patient (the BC group) were much less interested in the predictive test for HBC; a negative intention was expressed by two thirds of the BC group. This lack of interest is not only much larger than in previous studies among high risk women,13-15 20 but also more pronounced than in other studies among women with breast cancer in the family who have no increased risk for the disease.19 28 33 The discrepancy in our findings might be explained by cultural differences in dealing with risks and preventive options in the context of breast cancer38 or by specific characteristics of our sample. Being students at the Institute for Family Sciences, they might have been more interested in the relational and/or psychological issues in this context, rather than in technical information. Additionally, the kind of information that we provided on the predictive test for HBC, especially on the uncertainties and limitations involved, could have led to more reluctance for testing.39 Another explanation could be the method of recruitment of the study sample; our findings are based on a community sample without selection for a family history of breast cancer or breast related problems, while this kind of selection did take place in most other studies. The question about having a predictive test for HBC probably seems less hypothetical or unexpected in such selected samples, which might have resulted in less reluctant reactions than in our BC group. This may especially be the case when comparing with studies conducted on high risk families in a hereditary cancer registry and/or as part of a thorough research protocol. However, since the information on the number of relatives with breast cancer and/or the degree of kinship in our BC group was not always complete and could not be confirmed, more detailed comparisons with other studies are difficult.

Despite its lack of specification, the occurrence of breast cancer in the family had a strong independent association with uninterest in the predictive test for HBC. As shown by logistic regression analysis, women in the BC group were more than three times more likely to express uninterest in the test. To our knowledge, our study is the first to show such a strong negative relation between breast cancer in the family and interest in the predictive test. Shilohet al 33 observed a higher proportion of extreme rejection of the predictive test among at risk relatives of breast cancer patients (although their mean reported intention did not differ from the mean in the group of relatives without an increased risk). The greater uninterest among women who have breast cancer in the family in our study might have been the result of a stronger avoidance reaction in the BC group; because of their emotional involvement with breast cancer in the family and/or their higher perceived susceptibility to the disease, these women want to avoid the threatening possibility of detecting that they are carrying a HBC mutation. The stronger emotional involvement in the BC group is corroborated by the greater tendency in this group to give emotional explanations for the intention regarding predictive testing than in the No BC group. The operation of self-protective avoidance tendencies among at risk relatives of breast cancer patients was also suggested by Shiloh et al 33 and is in line with the idea that too much fear can lead to inaction (see also the conflict theory of Janis and Mann40). This idea receives further support from the negative univariate association between perceived susceptibility to breast cancer and the intention to have a predictive test for HBC observed in our study. Obviously, this contrasts with the predictions of the Health Belief Model. However, although the Health Belief Model has proven to be a valuable framework for understanding and predicting reactions to health threats, it has to be recognised that it is a rational, cognitive model which pays insufficient attention to emotional mechanisms. The importance of emotions in intentions to take a genetic test is illustrated in a study by Wroe et al 25; they found that emotional reasons were reported more frequently by people who had already actively thought about having a specific genetic test than by students for whom the test was hypothetical. Audrain et al 41 and Evers-Kiebooms et al 42 also stress the role of emotions in decisions about genetic testing. An example of an emotional factor that could have played a mediating role in not wanting a predictive test for HBC is self-blame or guilt about passing the disease onto the children.43 This might have especially been the case in our sample of students in Family Sciences, for whom family relations are likely to be of particular interest. Indirect support for this possibility stems from the logistic regression analyses on the total sample and on the No BC group; a higher number of children was significantly associated with higher odds of not wanting the test. However, this kind of independent association remained absent in the BC group.

An alternative explanation for the reaction of the BC group in our study against the predictive test is a more rational one. The experience with breast cancer in the family might have led to more awareness concerning the lack of effective preventive and/or therapeutic measures for the disease than in the No BC group, thereby reducing the perceived benefits of having a predictive test for HBC and/or increasing the perceived barriers or costs in the BC group. As such, the uninterest in the predictive test among the women in the BC group might have been the result of a rational decision based on the weighing up of their perception of costs and benefits. A similar systematic and rational process in the No BC group, with a different perception of barriers and benefits owing to the absence of familial experience with breast cancer, might have resulted in interest in the test. The differential perception of barriers and benefits of the predictive test for HBC according to the occurrence of breast cancer in the family is indeed supported by our findings: while the No BC group judged the benefits as more important than the barriers (a pattern that also emerged in previous studies14 20 28 32), the dominance of benefits disappeared in the BC group. On the other hand, as far as the explanatory value of these two Health Belief Model components is concerned, the results of the logistic regression analyses did not differ according to the occurrence of breast cancer in the family. In the BC group as well as in the No BC group, the perceived benefits were the first to enter the regression, while the perceived barriers remained absent. The failure of the perceived barriers component to enter the logistic regression can partly be explained by its substantial correlation with the other components of the Health Belief Model (table 3). However, this also suggests that the intentions in the No-BC group as well as in the BC group, despite the equivalence in the importance ratings of benefits and barriers in the latter group, were disproportionally affected by the perception of the benefits of the predictive test for HBC. A similar result was obtained by Lerman et al 32 in their multivariate analysis of BRCA1 test use. This underlines that providing comprehensive information on the complexities, the limitations, and the uncertainties involved in predictive testing for HBC (as well as on its benefits) is crucial for genetic counselling as well as public education purposes. Moreover, research has indicated that the intentions regarding genetic testing are not only influenced by the content of the information that is given, but also by the focus of attention.27 44Therefore, it is important to encourage and help people to consider all aspects of the test and all of its possible consequences, negative as well as positive ones. In a genetic counselling context, it was furthermore shown by Lerman et al 28 that a personalised approach extending beyond the standardised provision of information and giving room to the discussion of emotions can modify the evaluation of benefits and costs of the predictive test for HBC, perhaps through the more thorough processing of the information provided. Indeed, genetic counsellors should be sensitive to interpersonal differences in emotional and informational needs and priorities as well as in the diversity of reasons for predictive test requests.45 46 For instance, older women might be more concerned about their children's risks or about age related health problems than about their own genetic susceptibility to breast cancer.23 46 Our finding that older women in the BC group tend to be more reluctant about a predictive test for HBC for themselves is illustrative in this context. General concerns about the development of a predictive test for HBC as measured by the general attitude score seem not to be a priority in the BC group. Only for women who have no relatives with breast cancer does such a general measure play a role in their intention to have a test. When breast cancer does occur in the family, the influence of the general attitude score seems to be outweighed by the more personalised and instrumental measure concerning the perceived benefits of the predictive test. A similar finding concerning the influence of general attitudes towards health and medical testing has been reported by Shiloh et al.33

Overall, the results of our study show that the perceived benefits component is the most powerful Health Belief Model component in explaining interest in the predictive test for HBC. However, the absence of an independent association with perceived seriousness, perceived susceptibility, and perceived barriers does not mean that these factors are not important. They can influence other variables in the chain of the cognitive-emotional decision making process about the predictive test for HBC. Awareness of the possibility of their mediating role, as well as of the potential influence of emotions and/or more general concerns about the applications of the new genetic technology, is important for health care providers at different levels: at the level of genetic counselling, to facilitate free and informed decisions about predictive testing for HBC and at the level of community and clinical education programmes, to design targeted information addressing the specific needs and concerns of women at different risk levels. Although past experience with predictive testing for Huntington's disease47 and with carrier testing for cystic fibrosis48 has shown that reported interest in genetic testing cannot be equated with actual uptake, the results of our study and previous research on the predictive test for HBC are valuable in helping to reach these goals.

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