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Expectations and Cancer: Does How We Think Matter?

New research explores how expectations relate to cancer prevention and treatment

At the start of a new year, some of us look for renewal, make resolutions, and recommit ourselves to goals. We develop hopes, and expectations, about what the future will hold-- especially if we are successful in keeping up an exercise or diet regime! Thus, our expectations are connected to our health. New research is showing that expectations also can have an impact vis-à-vis cancer prevention and treatment.

Psychologists have studied how people make decisions about preventive health behaviors (i.e., wearing sunscreen) and have often considered predictors such as: how high people perceive their risk for a particular outcome to be, how serious they think the condition they may prevent is, and their perceptions about what the social norms are for engaging in a preventive behavior. They also have studied the potential influence of physicians’ recommendations to engage in a prevention behavior. A newer focus is looking at how people expect engaging in a prevention behavior will make them feel. For instance, intentions to engage in a health relevant behavior that are based on one’s anticipated emotional reaction(s) have been found to be significantly stronger predictors of actual behavior.1

One particular example where the role of expected emotional reactions has been considered is in addressing the low rates of uptake of chemopreventive medication (i.e., tamoxifen or raloxifene) among women at elevated risk of breast cancer. Although the likelihood for reducing the risk of breast cancer with these medications is fairly significant, women avoid these options not only because of the potential for worrisome side effects (i.e., hot flashes and, rarely, more serious outcomes like endometrial cancer) but also because they anticipate that taking a medication regularly over a long period of time will not be reassuring, but stressful. To examine this phenomenon, postmenopausal women at risk for breast cancer who were enrolled in a randomized trial of an internet-based cancer chemoprevention decision aid were queried about how they expected taking the medication would make them feel.2 The majority of women, even those who had been exposed to the decision aid, did not anticipate that taking a cancer chemopreventive medication would make them feel less stressed about their health. Furthermore, those with more negative expectations about how they would feel were less predisposed to take the medication and less likely to actually take it at a 3-month follow up.

In a related line of research, cancer patients’ expectations about the likelihood that they will experience treatment side effects such as nausea, pain, fatigue, and vomiting, also has been found to predict the extent to which they subsequently experience them.3 In the case of these symptoms, which are not under voluntary control, the connection between expectations and experience is thought to be especially strong and self-reinforcing: when an expectation is confirmed with the experience of a symptom, this perpetuates a sort of self-fulfilling prophesy that is even beyond conscious control.

These are examples where anticipating negative future states may hamper ideal outcomes. Unfortunately, our expectations can be inaccurate and biased, by, for example, focusing disproportionately on only the most stressful aspects of future situations, preventing us from taking reasoned action. In addition, we are notoriously inaccurate in affective forecasting, or predicting how we will feel following taking a particular course of action. Thus, basing decisions on how we expect we will feel can be faulty. Also, expectations of potential treatment side effects may be well founded, but can take on a life of their own. Such expectations are so potent that they can result in experiences of unpleasant symptoms even in response to inert agents (these are termed nocebo effects, similar but opposite in effect to the better-known placebo effects).

In contrast, there also are examples whereby positive expectations can have salutary outcomes in the cancer context. For example, adult survivors of childhood cancer who had more positive expectations about the course of their illness (i.e., endorsing statements like “when I think about my illness I assume all will go well”) had better health-related physical, and especially mental, quality of life.4 Similarly, in a longitudinal study, prostate cancer patients who had more positive prostate cancer-specific expectations before their surgery (i.e., regarding anticipated urinary problems, satisfaction with sexual functioning, confidence in sexual abilities, affection from their partners, making informed treatment decisions, regret about treatment decisions, worry about health, and outcomes of cancer treatment) had superior quality of life one year later.5 So, expectations have the potential to influence the experience of cancer, for worse and for better; understanding them may be a first step in productively limiting or harnessing their effects.


1 Conner, M., McEachan, R., Lawton, R., & Gardner, P. (2016). Basis of intentions as a moderator of the intention–health behavior relationship. Health Psychology, 35, 219-227. doi:10.1037/hea0000261

2 Hoerger, M., Scherer, L. D., & Fagerlin, A. (2016). Affective forecasting and medication decision making in breast-cancer prevention. Health Psychology, 35, 594-603. doi: 10.1037/hea0000324

3 Sohl, S. J., Schnur, J. B., & Montgomery, G. H. (2009). A meta-analysis of the relationship between response expectancies and cancer treatment-related side effects. Journal of Pain And Symptom Management, 38, 775-784. doi:10.1016/j.jpainsymman.2009.01.008

4 Stam, H., Grootenhuis, M. A., Caron, H. N., & Last, B. F. (2006). Quality of life and current coping in young adult survivors of childhood cancer: Positive expectations about the further course of the disease were correlated with better quality of life. Psycho-Oncology, 15, 31-43. doi:10.1002/pon.920

5 Thornton, A. A., Perez, M. A., Oh, S., & Crocitto, L. (2012). Optimism and prostate cancer-specific expectations predict better quality of life after robotic prostatectomy. Journal of Clinical Psychology in Medical Settings, 19, 165-176. doi:10.1007/s10880-011-9270-3