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Journal of Clinical Oncology, Vol 23, No 27 (September 20), 2005: pp. 6623-6630 © 2005 American Society of Clinical Oncology. DOI: 10.1200/JCO.2005.07.171 Explaining Differences in Attitude Toward Adjuvant Chemotherapy Between Experienced and Inexperienced Breast Cancer PatientsFrom the Department of Medical Decision Making, Leiden University Medical Center, Leiden, the Netherlands Address reprint requests to S.J.T. Jansen, PhD, Department of Medical Decision Making, J10-S, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, the Netherlands; e-mail: s.jansen{at}otb.tudelft.nl
PURPOSE: Previous studies have shown that patients who have experienced adjuvant chemotherapy (experienced patients) have a more favorable attitude towards chemotherapy than those who have not (inexperienced patients). However, not much is known about the reasons underlying this difference. According to the Theory of Planned Behavior, the attitude towards a particular behavior (eg, accepting chemotherapy) is based on beliefs about the likelihood of outcomes of the behavior and the evaluations of these outcomes. We used this theory to explore in what way the beliefs of experienced patients differed from those of inexperienced patients. PATIENTS AND METHODS: A cross-sectional survey was undertaken among 719 patients who had been treated for early-stage breast cancer between 1998 and 2003. Patients were asked, first, to indicate the likelihood of six positive and six negative outcomes of undergoing chemotherapy and, second, to give their evaluation of these outcomes. RESULTS: Four hundred forty-six women filled in the questionnaire (response rate, 62%). As hypothesized, experienced patients (ie, patients who had been treated with adjuvant chemotherapy as part of their primary treatment plan) had a more positive attitude towards chemotherapy. Experienced patients provided higher likelihood estimates of treatment advantages, such as life prolongation. In addition, they evaluated the positive outcomes of chemotherapy more favorably. With regard to the negative outcomes of chemotherapy, few differences were observed between treatment groups. CONCLUSION: Experienced patients have more confidence in the positive outcomes of chemotherapy than inexperienced patients. This might be the result of a cognitive mechanism to justify the way in which patients were treated.
Adjuvant chemotherapy is often prescribed to women with early-stage breast cancer in an effort to prevent disease recurrence and improve long-term survival rates. However, the choice for adjuvant chemotherapy involves a trade-off between a relatively small increase in the chance of survival at the cost of experiencing substantial adverse effects of treatment. For example, an overview of randomized trials showed that in women between 50 and 69 years of age with axillary-node-negative breast cancer, the use of adjuvant chemotherapy increases the mean estimated 5-year disease-free survival by 6.3% (from 70.3% to 76.6%).1 This result suggests that in a similar patient group only six out of a total of 100 treated patients would benefit from adjuvant chemotherapy. To explore whether the adverse effects of chemotherapy outweigh the benefits, previous studies have sought to determine the preferences of breast cancer patients with regard to adjuvant chemotherapy.2-8 One method that has been used to access patients' preferences is the probability trade-off method, also known as treatment preference method or decision board. This method requires the respondent to consider the adverse effects of various treatment options (including no treatment) together with the possible benefits of those treatments and the probabilities of obtaining those benefits.9 The relative strength of preference for a treatment is assessed by determining the minimum benefit needed, in terms of an increased chance of cure, prolongation of life, or decreased chance of recurrence, in order to accept treatment. A consistent finding of studies into patients' preferences for chemotherapy is that patients who have experienced this treatment have a more favorable attitude towards this treatment than patients who have not experienced it or healthy respondents.2,4,10-14 For example, Jansen et al2 asked breast cancer patients to indicate the minimum benefit, in terms of improved 5-year disease-free survival, needed to find adjuvant chemotherapy acceptable. In patients who had recently been treated with chemotherapy (experienced patients), the median minimum benefit to accept treatment was 1%. In contrast, the median minimum benefit of patients who had not been treated with chemotherapy (inexperienced patients) and who had been interviewed at the same point in time after surgery was 15%. It is important to understand the causes of this discrepancy in order to decide whose judgments to use in treatment decision making. One explanation for the discrepancy that has been mentioned in the literature is positive experience of the treatment.4,10,12,13 Patients who have experienced chemotherapy in the past may be less fearful of its potential negative effects and more comfortable with their ability to cope with the physical, social, and emotional aspects of treatment.4 However, we showed in a previous study that the preferences of patients who were about to start adjuvant chemotherapy, but had not yet started, were already statistically significantly more positive than the preferences of comparable patients for whom chemotherapy was not part of the treatment plan.2 This result suggests that it is not the experience per se that is responsible for the more positive preferences of experienced patients. Therefore, we sought another explanation and hypothesized that patients may have a desire to believe that the previously made treatment decision is the correct one and that they will try to justify this decision. As far as we know, this second explanation, which has been raised by others,4,10 has not been verified in previous research. A well-known model used to predict behavior is the Theory of Planned Behavior.15 This behavioral model has been used successfully to predict a variety of health-related behaviors (overview in Armitage and Conner16). According to this model, the attitude towards a particular behavior (eg, accepting chemotherapy) is based on beliefs about the positive and negative outcomes of the behavior. Respondents are asked to provide an estimation of the chance that a certain outcome will occur (eg, "Will I experience side effects, such as nausea, fatigue, and hair loss"?) and to provide an evaluation of these outcomes (eg, "If I experience side effects, such as nausea, fatigue, and hair loss, I find this ...?"). The Theory of Planned Behavior provides a useful framework for exploring in more detail why patients with experience of adjuvant chemotherapy and those without differ in their attitude towards chemotherapy, because it provides insight into the underlying beliefs that comprise the attitude. Our research may provide more insight into the deliberations that play a role for patients when considering adjuvant chemotherapy. If more is known about patients' beliefs with regard to the positive and negative outcomes of chemotherapy, then doctors may be able to explain this treatment in such a way that they support patients to make the optimal treatment decision. Our research goal was to explore in what way the beliefs of experienced patients differ from those of inexperienced patients. In line with the proposed explanation that patients want to believe that the previous decision for treatment was the correct one, we hypothesized that experienced patients would provide higher estimates of the chances of obtaining positive outcomes of chemotherapy (eg, increased chance of cure) and would evaluate these outcomes more favorably than inexperienced patients. Similarly, we hypothesized that experienced patients would provide lower estimates of the chances of obtaining negative outcomes of chemotherapy (eg, adverse effects of treatment) and would evaluate these outcomes more favorably than inexperienced patients.
Patients The Leiden University Medical Center (Leiden, the Netherlands) cancer registry identified all patients who had undergone breast surgery for early-stage breast cancer between January 1, 1998, and December 31, 2002, and who did not have distant metastasis at the time of the selection. This procedure yielded the names and addresses of 719 patients. These patients were sent a letter of invitation in which the study was explained. Patients could indicate on a reply sheet whether they wanted to receive the questionnaire and could return this sheet in a prepaid envelope. The questionnaire and a prepaid envelope were sent to patients who responded positively to our request. Patients who did not reply received one reminder. The study was approved by the Medical Ethics Committee of the Leiden University Medical Center.
Methods
According to the Theory of Planned Behavior, one's attitude is based on beliefs about the likelihood of outcomes of the behavior (called "belief strength") and the evaluations of these outcomes (called "outcome evaluation"). We measured belief strength by asking patients to indicate the perceived probability that undergoing chemotherapy would produce each of the 12 outcomes. We provided a five-point response scale: "definitely not," "probably not," "maybe, maybe not," "probably," and "definitely." Belief strength is defined as the subjective probability that a given behavior will produce a certain outcome. In light of this definition, the scores were transformed to form a 0 to 1 probability scale (ie, 0, 0.25, 0.5, 0.75, 1.0), as suggested by Ajzen.15 We measured outcome evaluation by asking patients to indicate their evaluation of the 12 outcomes on a five-point scale with the following answering categories: "very unfavorable," "unfavorable," "neither favorable, nor unfavorable," "favorable," and "very favorable." The scores are assumed to form a bipolar continuum, from a negative evaluation on one end to a positive evaluation on the other. For this reason, the scores ranged from –2 "very unfavorable" to 2 "very favorable," (ie, –2, –1, 0, 1, 2), as suggested by Ajzen.15 Product scores were computed by multiplying, for each of the 12 outcomes, the patient's belief strength by outcome evaluation, resulting in "behavioral beliefs."15 By applying this procedure, beliefs have more impact on the attitude as they are perceived to be more likely and to be either very favorable or very unfavorable. The behavioral beliefs were added to form the attitude score. Because some patients had missing answers, each patient's total attitude score was divided by the number of beliefs that the patient had responded to. If patients had more than four missing answers, the attitude score was not calculated. The potential range of attitude scores lies between –2 (very negative attitude towards chemotherapy) and +2 (very positive attitude towards chemotherapy). For a brief overview of the terms used in our study, see Table 1.
The questions about chemotherapy were preceded by information on the procedure and potential adverse effects of adjuvant chemotherapy. In the questionnaire, we asked patients to provide information on the following characteristics: age, marital status, being a parent, having children living at home, occupational status, education, and self-rated health. Self-rated health was measured by means of a Visual Analog Scale, ranging from 0 ("death") to 1 ("perfect health"). Furthermore, patients were questioned about the following clinical and treatment characteristics: date and type of surgery performed (breast-conserving surgery v mastectomy) and whether or not they had been treated with adjuvant chemotherapy, postoperative radiotherapy, and adjuvant hormonal therapy. Information on tumor stage was provided by the hospital cancer registry.
Analysis If significant differences in baseline characteristics were found, we included these potential confounders as covariates in our analyses. To analyze group differences with regard to belief strength, we used multivariate analysis of covariance. We included the 12 scores for belief strength as dependent variables, having experienced adjuvant chemotherapy as a between-group factor, and the potential confounders as covariates. We repeated this procedure for the 12 scores for outcome evaluation and for the 12 behavioral beliefs scores. For the analysis of attitude, we used univariate analysis of covariance and followed the same procedure. Thus, in total we performed three multivariate analyses of covariance and one univariate analysis of covariance.
Description of the Patient Group Between February and April 2003, 719 letters were sent in which we asked patients to participate in the study. One hundred two patients (14%) indicated that they did not want to receive the questionnaire, five patients (1%) were deceased, four patients (0.5%) were not eligible due to dementia (as indicated by their family), six patients (1%) had moved, and 72 patients (10%) did not respond at all. Five hundred thirty patients (74%) indicated that they wanted to receive the questionnaire. Four hundred forty-eight questionnaires were returned (85% of 530; 62% of 719). Two patients (0.5%) turned out to be ineligible because data from the cancer registry showed that they had supraclavicular lymph node metastases, which we considered to be a distant metastasis. Of the remaining 446 patients, 175 (39%) had experienced adjuvant chemotherapy. Some patients were currently treated with adjuvant hormonal therapy. Treatment with postoperative radiotherapy and adjuvant chemotherapy, if applicable, had been completed before participation in this study. Note that none of the patients had been treated for metastasized disease because this was an exclusion criterion. Patient characteristics of both experienced and inexperienced patients are provided in Table 2. Experienced patients differed statistically significantly (P < .05) from inexperienced patients on a number of patient characteristics. With regard to sociodemographic characteristics, experienced patients were younger, were more frequently married or living together, more frequently had children living at home, more frequently had paid work, and had been educated longer. With regard to disease- and treatment-related characteristics, experienced patients more frequently had stage II disease, more frequently had undergone a mastectomy, more frequently had experienced hormonal therapy, and had had breast surgery longer ago. All potentially confounding patient characteristics were included as covariates in all analyses. No differences were found for being a parent (P = .66), self-rated health (P = .90), and having experienced radiotherapy (P = .87).
Belief Strength The multivariate analysis of covariance showed a significant difference (P < .01) in overall mean belief strength between experienced and inexperienced patients. Marital status (P < .01) and education (P < .01) were the only covariates that reached statistical significance in the analysis. Married or cohabiting patients generally provided higher estimates of the likelihood of treatment outcomes (both positive and negative). Patients with more years of education generally provided higher estimates of negative treatment outcomes and lower estimates of positive treatment outcomes. The univariate results of the multivariate analysis showed statistically significant (P < .01) differences between experienced and inexperienced patients for three of the six negative outcomes of chemotherapy. Experienced patients estimated that they had a greater chance of experiencing adverse effects of chemotherapy. Furthermore, these patients estimated that they had a smaller chance of their state of health being bad when treated with chemotherapy and of being worn out by frequent visits to the hospital. Regarding the positive outcomes of chemotherapy, experienced patients provided statistically significant (P < .05) higher estimates of each of the positive outcomes. Figure 1 provides the mean scores for belief strength, adjusted for all potential confounders.
Outcome Evaluation The univariate results of the multivariate analysis showed a statistically significant (P < .01) difference between experienced and inexperienced patients for one of the six negative outcomes of chemotherapy. Experienced patients found it less unfavorable than inexperienced patients to be worn out by frequent visits to the hospital. Note that the univariate tests for "I'll recover more slowly, physically, after surgery" and "I'll think I'm in a bad state" reached borderline significance (P = .06 and P = .08, respectively). With regard to the positive outcomes of chemotherapy, experienced patients valued all six outcomes statistically significantly (P < .05) more favorably than inexperienced patients. The adjusted mean scores for outcome evaluation are provided in Figure 2.
Behavioral Beliefs Figure 3 shows the adjusted mean behavioral beliefs (ie, the product scores of belief strength and outcome evaluation). Larger scores refer to more impact of the particular outcome on the attitude (either positive or negative). The multivariate analysis showed a statistically significant (P < .01) difference in overall mean behavioral beliefs between experienced and inexperienced patients. Education (P < .01), and time passed between breast surgery and filling out the questionnaire (P < .05) were covariates that reached statistical significance. The outcomes, and especially the negative outcomes, were generally more important to patients with more years of education. The negative outcomes were generally less important to patients who had had surgery longer ago. Statistically significant differences (P < .01) between the two treatment groups were observed for two of the six negative outcomes of chemotherapy. Being in a bad state of health when treated with chemotherapy and being worn out by frequent visits to the hospital were less important to experienced patients than to inexperienced patients. Note that the difference for "I'll look awful" reached marginal statistical significance (P = .07). Finally, all six positive outcomes of chemotherapy were statistically significantly (ie, P < .01) more important to experienced patients than to inexperienced patients.
Attitude Scores
We used the Theory of Planned Behavior to explore the attitudes of experienced and inexperienced patients with regard to adjuvant chemotherapy. Our results showed that experienced patients have a more favorable attitude towards the treatment that they have experienced than inexperienced respondents. These results are in agreement with findings in the literature.2,4,10-13 According to the Theory of Planned Behavior, the attitude towards a certain behavior is based on beliefs about the likelihood of the outcomes of that behavior and the evaluation of these outcomes. Because our design was set up according to this theory, we were able to obtain more insight into the deliberations that play a role for patients when considering adjuvant chemotherapy. We were especially interested in differences in beliefs between experienced and inexperienced patients. Our results showed that experienced and inexperienced patients differed in their beliefs with regard to both the likelihood and the evaluation of potential outcomes of chemotherapy. Furthermore, patient groups differed more with regard to the positive outcomes of chemotherapy than with regard to the negative outcomes. One hypothesis that has been mentioned in the literature to explain the discrepancy between the preferences obtained from experienced and inexperienced respondents is positive experience of the treatment.4,10,12,13 Patients who have experienced chemotherapy may be less fearful of its potential negative effects and more comfortable with their ability to cope with the treatment.4 However, our results showed that experienced patients provided a higher mean estimate of experiencing adverse effects of treatment and did not evaluate this outcome more favorably than inexperienced patients. These findings provide further evidence against the hypothesis that the more positive preferences of experienced patients may be explained solely by positive experience of the treatment. A second explanation implied that patients might have a desire to believe that the prior decision for treatment or no treatment was the correct one and that they will try to justify this decision (justification hypothesis).2,4,10 In line with this explanation, we hypothesized that experienced patients would provide higher likelihood estimates of positive outcomes and would evaluate these outcomes more favorably. In addition, they would provide lower estimates of the negative outcomes and would evaluate these outcomes more favorably. Our results showed that this hypothesis was confirmed for the positive outcomes but not for the negative outcomes. These findings provide evidence for the working of some psychological mechanism that changes the way in which patients think about the positive outcomes of chemotherapy after experiencing this treatment. Several theoretical perspectives may account for this psychological mechanism, including Lazarus and Folkman's theory on stress and coping (cognitive reappraisal),18 Dissonance Reduction Theory by Festinger, 19 and Differentiation and Consolidation Theory by Svenson.20 The latter two theories focus on the perceived responsibility and freedom of choice as conditions for changing cognitions. However, a previous study showed that 65% of patients to whom chemotherapy was offered perceived that they had no choice but to accept this treatment.21 Therefore, Lazarus and Folkman's theory on stress and coping may be the best explanation for the finding that experienced patients have more confidence in the benefits of chemotherapy. We will briefly explain Lazarus and Folkman's theory. First, the theory assumes an inconsistency between initial preference and treatment. Second, a negative emotional state (stress) is assumed. Third, the theory points to the adjustment of the cognitive underpinning of the preference (positive reinterpretation). Thus, we change how we think about a situation in order to decrease its emotional impact. When applied to our study, many patients who were treated with adjuvant chemotherapy will initially have had a preference for no chemotherapy, because of the burden of this treatment. Undergoing chemotherapy when this is not the preferred strategy may cause strong and negative emotional feelings. To reduce those feelings, the beliefs about chemotherapy will be changed so that the benefits of the treatment seem greater. This is termed cognitive reappraisal. Cognitive reappraisal is usually studied with regard to negative events that have already happened. For instance, Taylor, Lichtman, and Wood22 observed that breast cancer patients adapted to their situation by focusing on aspects that they scored relatively well on, by comparing themselves with others who were worse off, or by thinking about the positive elements of their experience. The fact that a psychological mechanism such as cognitive reappraisal may have such a large impact on the attitude towards chemotherapy has important consequences for the field of oncology. Many studies into treatment preferences have been carried out in patients who have already undergone the particular treatment.5,6,8,23,24 As a result, the preferences obtained in these studies may have been too positive because of cognitive reappraisal. Furthermore, this psychological mechanism may also be responsible for the finding that breast cancer patients who experienced adjuvant chemotherapy generally overestimate the effectiveness of this treatment.5 Further research is needed to explore the effects of this psychological mechanism in more detail. A limitation of our study is that our treatment groups differed considerably with regard to patient characteristics. All these differences, except for having undergone breast surgery longer ago, can be attributed to the fact that the prescription of adjuvant chemotherapy is dependent on age and tumor characteristics. Chemotherapy is more frequently prescribed to patients who are younger (and thus, for example, more frequently have children living at home), and to patients who have larger tumors (and thus, for example, more frequently have undergone mastectomy). We have no explanation for the difference with regard to the time passed between surgery and filling out the questionnaire. However, the differences in attitude and beliefs between treatment groups were independent of differences in patient characteristics. Moreover, a recent review showed that patients' preferences are hardly influenced by patient characteristics.14 In conclusion, in treatment decision making we should be aware that patients' preferences might be influenced by a cognitive mechanism that brings about a rightful justification for having undergone chemotherapy by influencing the beliefs about the positive outcomes of that treatment.
The authors indicated no potential conflicts of interest.
Supported by the Dutch Cancer Society Grant No. UL 2000–2334. Authors' disclosures of potential conflicts of interest are found at the end of this article.
1. Early Breast Cancer Trialists' Collaborative Group: Polychemotherapy for early breast cancer: An overview of the randomised trials. Lancet 352:930-942, 1998[CrossRef][Medline] 2. Jansen SJT, Kievit J, Nooij MA, et al: Patients' preferences for adjuvant chemotherapy in early-stage breast cancer: Is treatment worthwhile? Br J Cancer 84:1577-1585, 2001[CrossRef][Medline] 3. Levine M, Gafni A, Markham B, et al: A bedside decision instrument to elicit a patient's preference concerning adjuvant chemotherapy for breast cancer. Ann Intern Med 117:53-58, 1992
4. Lindley C, Vasa S, Sawyer WT, et al: Quality of life and preferences for treatment following systemic adjuvant therapy for early-stage breast cancer. J Clin Oncol 16:1380-1387, 1998 5. Ravdin PM, Siminoff IA, Harvey JA: Survey of breast cancer patients concerning their knowledge and expectations of adjuvant therapy. J Clin Oncol 16:515-521, 1998[Abstract] 6. Simes RJ, Coates AS: Patient preferences for adjuvant chemotherapy of early breast cancer: How much benefit is needed? J Natl Cancer Inst Monogr 30:146-152, 2001
7. Whelan T, Sawka C, Levine M, et al: Helping patients make informed choices: A randomized trial of a decision aid for adjuvant chemotherapy in lymph node-negative breast cancer. J Natl Cancer Inst 95:581-587, 2003 8. Zimmermann C, Baldo C, Molino A: Framing of outcome and probability of recurrence: Breast cancer patients' choice of adjuvant chemotherapy (ACT) in hypothetical patient scenarios. Breast Cancer Res Treat 60:9-14, 2000[CrossRef][Medline]
9. Llewellyn-Thomas HA, Williams JI, Levy L, et al: Using a trade-off technique to assess patients' treatment preferences for benign prostatic hyperplasia. Med Decis Making 16:262-272, 1996 10. Cullen MH, Billingham LJ, Cook J, et al: Management preferences in stage I non-seminomatous germ cell tumors of the testis: An investigation among patients, controls and oncologists. Br J Cancer 74:1487-1491, 1996[Medline] 11. McQuellon RP, Muss HB, Hoffman SL, et al: Patient preferences for treatment of metastatic breast cancer: A study of women with early-stage breast cancer. J Clin Oncol 13:858-868, 1995[Abstract]
12. Yellen SB, Cella DF, Leslie WT: Age and clinical decision making in oncology patients. J Natl Cancer Inst 86:1766-1770, 1994 13. Stiggelbout AM, Kiebert GM, de Haes JC, et al: Surveillance versus adjuvant chemotherapy in stage I non-seminomatous testicular cancer: A decision analysis. Eur J Cancer 32A:2267-2274, 1996[CrossRef]
14. Jansen SJ, Otten W, Stiggelbout AM: A review of determinants of patients' preferences for adjuvant therapy in cancer. J Clin Oncol 22:3181-3190, 2004 15. Ajzen I: The Theory of Planned Behavior. Organ Behav Hum Decis Process 50:179-211, 1991[CrossRef] 16. Armitage CJ, Conner M: Efficacy of the Theory of Planned Behaviour: A meta-analytic review. Br J Soc Psychol 40:471-499, 2001[CrossRef][Medline] 17. Jansen SJT, Otten W, Baas-Thijssen MCM, et al: Adjuvant chemotherapy for breast and colorectal cancer: What do patients want, and why? Qual Life Res 12:802, 2003 (abstr 1360) 18. Lazarus RS, Folkman S: Stress, Appraisal And Coping. New York, NY, Springer Publishing Company, 1984 19. Festinger L: A Theory of Cognitive Dissonance. Stanford, CA, Stanford University Press, 1957 20. Svenson O: Differentiation and Consolidation Theory of human decision making: A frame of reference for the study of pre- and post-decision processes. Acta Psychol 80:181-197, 1992 21. Jansen SJ, Otten W, van de Velde CJH, et al: The impact of the perception of treatment choice on satisfaction with treatment, experienced chemotherapy burden and current quality of life. Br J Cancer 91:56-61, 2004[CrossRef][Medline] 22. Taylor SE, Wood JV, Lichtman RR: Attributions, beliefs about control, and adjustment to breast cancer. J Pers Soc Psychol 33:403-408, 1984 23. O'Connor AM: Effects of framing and level of probability on patients' preferences for cancer chemotherapy. J Clin Epidemiol 42:119-126, 1989[CrossRef][Medline] 24. O'Connor AM, Boyd NF, Warde P, et al: Eliciting preferences for alternative drug therapies in oncology: Influence of treatment outcome description, elicitation technique and treatment experience on preferences. J Chronic Dis 40:811-818, 1987[CrossRef][Medline] Submitted July 26, 2004; accepted May 11, 2005.
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Copyright © 2005 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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ABSTRACT
INTRODUCTION
.05; (**) P < .01.
2 test, where appropriate. 
= .77; experienced patients, 
