For years, various healthcare entities have worked to educate consumers about the importance of cancer screening.1,2 The risks associated with this screening have received less emphasis.3 As a result, screening is generally viewed as an obligation: 41% of Americans believe it would be irresponsible for an 80-year-old woman to decline a mammogram.1
It is time for providers to more thoroughly educate patients about both the benefits and risks of screening.2 The incongruent screening recommendations of national organizations (Table 13-7) point to a need for shared decision making.
In general, the medical community holds the inaccurate belief that high rates of cancer screening represent high-quality healthcare.2 "Effective" medical procedures are those for which the benefits far outweigh the risks; the goal is to ensure they are used.8 In "preference-sensitive" procedures, the values of the patient determine the effectiveness of the procedure.8 The goal is not necessarily to increase the uptake of these procedures, but to provide patients with the information, tools and support they need to personally weigh the risks and benefits.
Cancer screening for low-risk populations is one example of a preference-sensitive procedure that assesses apparently healthy people who do not display symptoms. Screening decisions should grow out of discussions with the patient.9
Benefits of Cancer Screening
Screening for breast cancer,3 cervical cancer5 and colorectal cancer 6,9 reduces associated mortalities. The median recommended screening age group experiences the highest level of benefit from these tests.4 However, no randomized controlled trials of good or fair quality show that screening reduces the mortality associated with prostate cancer.3,10,11 Mortality reduction is largely due to the early detection of less advanced cancer,3 detection of smaller tumors that are more responsive to treatment4 or detection of precursors to cancer, such as polyps, that can be removed or closely monitored.6,10
Early detection often provides patients with a greater variety of treatment options, including those that are less aggressive.3 However, screening may not be able to detect all presentations of the targeted cancer, and some detected cancers may have a poor prognosis.2,3 Because most recommendations require hundreds to thousands of patients to be screened for one life to be saved, most patients receive no benefits from screening. A select few benefit tremendously.2
Risks and Uncertainties
Nearly all screenings present risks for overdiagnosis and treatment of pseudodisease.2-4,6,7,11 Overdiagnosis occurs when psuedodisease - cancer that is not life threatening and would not become so during the patient's lifetime - is detected through screening and treated.
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For example, only 50% of ductal carcinoma in situ detected through mammography will progress to invasive breast cancer, yet nearly all patients are treated.9 Almost all early diagnoses of prostate cancer are also treated, even though it is nearly impossible to determine which patients will benefit from treatment.3 While cancer is more prevalent in older adults, this group benefits the least from early detection and early treatment because they are less likely to live the number of years needed for the cancer to progress to a life-threatening stage.4,6
While overdiagnosis is a greater risk for older adults, a false-positive result is a greater risk for younger patients.4 False positives often elicit anxiety, inconvenience and worry.7,9 They are not always resolved through repeat testing and often require invasive biopsy.3,5,11 Of women who participated in breast cancer screening, nearly 50% reported receiving false positives.9 The United States Preventive Services Task Force no longer recommends clinical breast exams or breast self-exams, in part due to the high number of false positives.4 False-positive results are also frequently associated with prostate-specific antigen (PSA) screening.3 False negatives occur to a lesser extent, most notably in PSA testing.3 Even when they effectively treat cancer, all interventions are associated with side effects. With localized prostate cancer, treatment options include radical prostatecetomy, external beam radiation therapy and radioactive seed implantation,7 each of which can result in erectile dysfunction, urinary incontinence, bowel dysfunction or even death.3,7
When treatment is not pursued, increased follow-up is often implemented with watchful waiting that includes repeat screenings to monitor progression, or even repeat biopsies to assist in determining when treatment would be most effective.2,3,5,7 These side effects are especially difficult in cases of pseudodisease and false positives. Lastly, screening, biopsy and monitoring procedures all bear innate risks. The associated anxiety, expense and risk for serious complication require consideration.4,6,7 For example, in the United States, perforation occurs in 3.8 of every 10,000 colonoscopies and other serious complications occur in 25 of every 10,000.6 In contrast, perforations occur in 4.6 of every 100,000 flexible sigmoidoscopies and serious complications occur in 3.4 of every 10,000.6 Given that both screening procedures produce similar benefits,6 patients should be aware of the risks and benefits of each (Table 2).2-7,9,11
Shared Decision Making
Shared decision making has been described as an ideal interaction.12 It incorporates the judgment of both the patient and the provider.13
The concept was formally articulated in a 1982 report on informed consent issued by the President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research. It described shared decision making as "a dialogue in which the professional seeks to help the patient understand the medical situation and available courses of action, and the patient conveys his or her concerns and wishes."
The process requires providers to educate each patient about specific circumstances related to personal health, to strive to understand each patient's needs and develop choices to meet the needs, and to present the choices in a way that enables patients to select one they prefer.14
In a literature review of 161 articles about shared decision making, nine essential elements emerged: defining or explaining the problem; presenting options; discussing benefits, risks and costs; discussing patient values and preferences; discussing patient ability and self-efficacy; discussing provider knowledge and recommendations; checking for and clarifying patient understanding; making or explicitly deferring a decision; and arranging follow-up.12
Shared decision making does not require a provider and patient to agree that the chosen course is the best option, but both must endorse it as the chosen option.13
Multiple studies have demonstrated the superiority of shared decision making over standard counseling, in which patients tend to have unrealistic expectations of benefits and harms and providers are poor judges of patient values, resulting in the overuse of treatments.8
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Since 2001, the American Cancer Society (ACS) has emphasized shared decision making for prostate screening. Organizations such as the USPSTF and the American Urological Association have started to emphasize this option as well.3 For breast cancer, colorectal cancer and cervical cancer screening, the ACS and USPSTF advocate for the full disclosure of risks, benefits and limitations of screening, as well as the consideration of patients' values.3
However, multiple studies have found shared decision making to be inconsistently used, with widely varying content and subpar implementation.3
Although most patients view healthcare providers as an important source for screening information,15 multiple surveys have documented inadequate education of patients and minimal patient inclusion in the decision making process.3 Less than half of patients are able to correctly answer questions about cancer incidence or mortality, with most overestimating.15 Nor are they able to correctly answer questions about cancer screening.16
Repeatedly, patients report that screening benefits are discussed in less than half of prescreening visits.15-17 Screening uncertainties are discussed in less than 25% of visits,15 and screening harms are discussed in less than 10% of visits.15,17 Patient preferences are pursued in 38% of visits, and patient understanding of information in 24%.15
In a survey of primary care physicians in Texas, 20.6% reported not having any prescreening discussions when ordering PSA testing.18 In a systematic review of shared decision making, providers identified time constraints as the foremost barrier to implementation of this process. This was followed by the perception that patients prefer a different decision making model and the belief that it is not necessary to ask patients how involved they would like to be in decision making.19 Conversely, patients have overwhelmingly identified providers' attitudes about shared decision making as facilitators for the process.20
The implementation of shared decision making can be increased with more widespread use by colleagues and by continuing education on the subject.20 Increased promotion of shared decision making by organizations, providers and educational sources can assist in transforming provider beliefs and attitudes about shared decision making from barriers to facilitators of implementation. Decision making aids are one means to overcome time constraints while facilitating quality decision making.
Decision Making Aids
A decision making aid is an exercise or tool that serves as an adjunct to prescreening conversations.21 It provides facts about the cancer and screening,8 explains screening and treatment options, 8,21 facilitates clarification of personal values about the benefits, risks and uncertainties of screening,13,21,22 and provides guidance for communication with providers.8,21 Its purpose is to assist patients to better participate in decision making8,13,21 and to make healthcare choices that match their values.8 These aids can be in the form of brochures, audiovisual recordings or interactive media.
Multiple studies have demonstrated that decision making aids are more effective than standard counseling in improving patient knowledge and expectations.21 These aids also influence the use of procedures and screenings.21,23 Shared decision making is supported by electronic infrastructures.8
A Viable Framework
In a time when screening benefits have been widely touted in a manner that often overshadows risks and uncertainties, providers and patients must work together to make screening choices that accurately reflect patient values and opinions. Shared decision making provides a viable framework for this.
1. Schwartz LM, et al. Enthusiasm for cancer screening in the United States. JAMA. 2004;291(1):71-78.
2. Welch HG. Informed choice in cancer screening. JAMA. 2001;285(21):2776-2778.
3. Smith RA, et al. Cancer screening in the United States, 2011: A review of current American Cancer Society guidelines and issues in cancer screening. CA Cancer J Clinic. 2011;61(1):8-30.
4. Screening for breast cancer: US Preventive Services Task Force Recommendation Statement. Ann Intern Med. 2009;151(10):716-726.
5. Screening for Cervical Cancer. U.S. Preventive Services Task Force Recommendation Statement. 2012. http://www.uspreventiveservicestaskforce.org/uspstf11/cervcancer/cervcancerrs.htm.
6. Screening for Colorectal Cancer: US Preventive Services Task Force recommendation statement. Ann Intern Med. 2008;149(9):627-637.
7. Screening for prostate cancer: US Preventative Services Task Force recommendation statement. Ann Intern Med. 2008;149(3):185-191.
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11. Lin K, et al. Benefits and harms of prostate-specific antigen screening for prostate cancer: An evidence update for the US Preventive Services Task Force. Ann Intern Med. 2008;149(3):192-199.
12. Makoul G, Clayman ML. An integrative model of shared decision making in medical encounters. Patient Educ Couns. 2006;60(3):301-312.
13. Charles C, et al. Shared decision-making in the medical encounter: What does it mean? (Or it takes at least two to tango). Soc Sci Med. 1997;44(5):681-692.
14. Making Health Care Decisions: The Ethical and Legal Implications of Informed consent in the Patient-Practitioner Relationship. Vol 1: The Report. President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research. Washington DC: US Government Printing Office; 1982. http://bioethics.georgetown.edu/pcbe/reports/past_commissions/making_health_care_decisions.pdf.
15. Hoffman RM, et al. Decision making processes for breast, colorectal, and prostate cancer screening: The DECISIONS survey. Med Decis Making. 2010;30(5 Suppl):S53-S64.
16. Chan EC, et al. Informed consent for cancer screening with prostate-specific antigen: how well are men getting the message? Am J Public Health. 2003;93(5):779-785.
17. Nekhlyudov L, Li R, Fletcher SW. Informed decision making before initiating screening mammography: does it occur and does it make a difference? Health Expect. 2008;11(4):366-375.
18. Linder SK, et al. Primary care physicians' reported use of pre-screening discussions for prostate cancer screening: a cross-sectional survey. BMC Family Practice. 2009;10:19. http://www.biomedcentral.com/1471-2296/10/19.
19. Gravel K, et al. Barriers and facilitators to implementing shared decision-making in clinical practice: A systematic review of health professionals' perceptions. Implement Sci. 2006;1(16). http://www.implementationscience.com/content/1/1/16.
20. Stacey D, et al. Decision coaching to support shared decision making: framework, evidence, and implications for nursing practice, education, and policy. Worldviews Evid-Based Nurs. 2008;5(1):25-35.
21. Elwyn G, et al. Developing a quality criteria framework for patient decision aids: online international Delphi consensus process. BMJ. 2006;333(7565):417.
22. O'Connor AM, et al. Do patient decision aids meet effectiveness criteria of the international patient decision aid standards collaboration? A systematic review and meta-analysis. Med Decis Making. 2007;27(5):554-574.
23. Volk RJ, et al. Patient education for informed decision making about prostate cancer screening: a randomized controlled trial with 1-year follow-up. Ann Fam Med. 2003;1(1):22-28.