Shared Decision Making (SDM) In Cancer Screening

Sarina Schrager, MD, MS, Gina Phillips, BA, and Elizabeth Burnside, MD, MPH, MS


     Shared decision making is a key component of patient centered care. Shared decision making involves bidirectional information flow between the clinician and the patient. In cancer screening discussions, the clinician provides information about the screening test and the disease and the patient provides information about his/her values relevant to the test and risk factors. Then the decision whether to undergo the screening test is made jointly by both parties. Several models are available to guide primary care clinicians in the process of shared decision making within a visit. This article describes several different models of shared decision making and provides case examples of how to use these models within a conversation about cancer screening.

What is shared decision making?:

     Shared decision making is a method of decision making that involves both the patient and the clinician in a bi-directional flow of information. The process involves information provided to the patient by the clinician about the screening service, and then elucidation of the patient’s thoughts and values about the specific test with the final decision made jointly by the patient/clinician dyad. Shared decision making is distinct from informed decision making. In informed decision making, the clinician provides information to the patient about the risks and benefits of the screening test and then the patient makes the decision. There is no bidirectional flow of information other than confirmation that the patient understands the information.

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     Shared decision making provides a patient centered approach to care in situations where there is more than one medically reasonable option. While not appropriate in clinical scenarios where the medical treatment is clear, such as antibiotics for meningitis or anticoagulation for a pulmonary embolus, shared decision making proves beneficial in situations where more than one treatment or screening decision is valid. This paper will focus on the use of shared decision making in cancer screening. There are a many screening options for primary care patients and good evidence that early detection of most cancers can lead to decreased mortality and morbidity from treatment. But, most of the screening methods also have possible harmful effects including overdiagnosis or over-treatment, associated anxiety with false positive results, and discomfort and harmful effects of diagnostic procedures. It is important that patients understand all of this information in order to make a decision about screening. The other integral part of shared decision making is the idea of including a patient’s values about screening.

Why should we do shared decision making?:

     In 2001, the Institute of Medicine published a report entitled Crossing the Quality Chasm that proposed patient centered care as one of the tenets of US healthcare for the future. The IOM defined patient centered care as, “care that is respectful of and responsive to individual patient preferences, needs and values”, and makes sure that “patient values guide all clinical decisions.” Shared decision making offers a framework for providing this kind of care. Specifically for cancer screening, shared decision making is an important part of evidence-based and patient centered care.

     Shared decision making can also improve patient satisfaction and potentially, by improving communication, affect medical malpractice claims. There is also some research that focuses on the use of shared decision making as a potential means to reduce health inequalities among underserved populations. Decision aids are often used in shared decision making to present information to patients about harms and benefits of a specific test and provide a venue for them to delineate their values about screening. Use of decision aids within a shared decision making conversation can improve care. A recent Cochrane review found that compared to regular care, use of decision aids:

  • Increased patients’ knowledge
  • Increased the proportion of people who had an accurate risk perception of the disease
  • Increased the proportion of people who chose an option that was in line with their values
  • Decreased decisional conflict
  • Had a positive effect on clinician-patient communication
  • Had a variable effect on length of visit (from −8 to + 23 minutes with a median increase of 2.5 minutes per visit)

     On a more practical level, shared decision making is mandated based on some recommendations. For example, in their 2016 update of recommendations for breast cancer screening, the USPSTF placed a “C” recommendation for mammography in women between 40–49 and recommended individual decision making based on values and personal risk. In order to get screening CT for lung cancer screening paid for by Medicare, physicians need to document that they had a shared decision making conversation with the patient and talked about the risks and benefits of screening.

     Even with all the evidence documenting that shared decision making improves patient care, it is not used frequently in primary care practices. One study found that the 3 most cited reasons for not using SDM in their patient encounters were: Time pressure within the visit

  • Lack of applicability due to patient characteristics
  • Lack of applicability due to the clinical situation.

Clinicians are more likely to use shared decision making if they believed that it improved the process of healthcare. Research on how to improve the adoption of shared decision making in practice has not been conclusive. Strategies to increase the use of shared decision making that focus on institutional changes (i.e. mailing decision aids to all patients before screening visits) show promise but may have logistical challenges.

How to do shared decision making:

     The Informed Medical Decisions Foundation has developed six key steps to be used in all shared decision making conversations. They are as follows:

  1. Invite the patient to participate—This key first step informs patients that they have options in terms of cancer screening and their values and preferences are an important part of the decision whether or not to get a particular screening test.
  2. Present the options—For example, there are a multitude of different ways to screen for colon cancer. In terms of breast cancer screening, women can choose to get a mammogram or not, every year or every other year.
  3. Provide information on benefits and risks—If a man decides to get a PSA, he needs to know what a positive result means, what the risks of prostate biopsy are, and the information on overdiagnosis of prostate cancer (i.e. detection of low grade cancer that would never have affected his life). He should also know that catching an aggressive cancer early may save his life.
  4. Assist patients in evaluating options based on their goals and concerns—For example, if an elderly man does not want to have surgery in any situation due to a bad reaction he has had in the past, then maybe lung cancer screening is not a good choice for him.
  5. Facilitate deliberation and decision making— The primary care physician can help patients make decisions based on their ongoing relationship and experiences treating other illnesses. Cancer screening decisions do not need to be made urgently, but can be discussed during a series of visits.
  6. Assist patients to follow through on their screening decisions—Members of the primary care team can aid patients in setting up appointments, providing information about the tests, and helping address any barriers to getting the screening test.

How to assess a patient’s values:

     Most primary care clinicians are not trained in assessing a patient’s values. Providers can ask people, what matters to you? But, how to integrate the answer into a clinical decision presents a challenge. There are many values clarification tools available in print and online. The most common type of values clarification exercises includes a set of pros and cons about any particular decision, but there is very little literature demonstrating the best way to assess values. Many resources use clinical vignettes that demonstrate different outcomes of each screening procedure. One of the most commonly used values clarification tools is the Ottawa Personal Decision Guide (available at This guide is available free online and provides a patient with a structured method of going through options of treatment or screening with a way to weigh the importance of each option based on his or her individual values. The Ottawa tool does not look at any condition specifically but instead demonstrates a framework of balancing harms and benefits of treatment or screening decisions.

How to present information about screening in ways patients can understand:

     Ideally, providers can have a conversation with their patients that informs them of the evidence behind a specific cancer screening test, the benefits (i.e. lives saved, cancers found early, etc) and the possible harms (false positives, anxiety about further testing, unnecessary biopsies, and overdiagnosis) and help them make a decision. Unfortunately, much of that information is complex and many guidelines do not weigh harms and benefits equally.

     Sharing information about risk can be complex. Many clinicians tend to use language that is technical. A recent systematic review looked at methods of communicating risk to patients and found that visual aids and absolute risk formats can help patients understand more complicated topics. Visual aids are often included in decision aids that demonstrate individual risk. They create a picture that helps explain numeric values. Visualizing health ( is a joint project of the Robert Wood Johnson Foundation and the University of Michigan Center for Health Communication that uses colorful graphs and pictures that can help communicate information about risk. An example of how to convert information into absolute risk is below.

Should say:
  • If 100 people have this test, 3 will have a positive result even though they don’t have cancer.
Should not say:
  • This test has a 3% false positive rate.
  • The specificity of the test is 97%.

Using decision aids:

     Decision aids are helpful to convey complex information about a specific topic. The Ottawa Personal decision aid is an example of an aid that can be printed out and given to patients. Online resources for decision aids are available as well.

Online decision aid resources:

     There are numerous models of shared decision making available to primary care physicians to use in cancer screening. All of the models incorporate the 6 key areas of shared decision making described above. We have chosen three models that we think are the most useful in cancer screening. The three models that we will demonstrate are the AHRQ SHARE method, the 5 A’s method described by the USPSTF, and the IAIS model described in a paper by Dr. David Price. The USPSTF model is designed specifically for screening and IAIS model is focused on combining EBM and SDM.

AHRQ SHARE method of SDM:

  1. Seek your patient’s participation
  2. Help your patient explore and compare treatment options
  3. Assess your patients values and preferences
  4. Reach a decision with your patient
USPSTF method (5, As)
Assess- the patient’s health needs and eligibility for preventive services, and patient’s desired role in decision making.
Advise—the patient about recommended screening, provide balanced information about the service. If appropriate (in A, B, and D recommendations) provide a recommendation.
Agree—elicit the patient’s values and determine preferences, negotiate a course of action
Assist—order service
Arrange—a follow up visit to review screening service in the future
IAIS model
Invite patient perspectives and concerns
Acknowledge patient perspectives and concerns
Instruct the patient about the evidence regarding the specific medical decision
Summarize a jointly developed plan

Case studies:

Case study: Using the 5 A’s method to talk about breast cancer screening.
     Nancy, a longtime patient of yours, comes to your clinic for a physical. While you are catching up with her, she tells you that the mom of one of her son’s classmates was just diagnosed with breast cancer at the age 41. Nancy is 45 years old and is now concerned that she has never had a mammogram.
You first Assess Nancy’s risk of breast cancer. After turning your computer screen so that Nancy can see, you use as an interactive tool to determine Nancy’s individual risk of developing breast cancer. The program concludes Nancy is at average risk, and you explain that out of 100 people just like her, 1–2 people would develop breast cancer in the next 10 years.
     You Advise Nancy on the current recommendations, benefits, harms, alternatives, and uncertainties of mammography screening for a woman with her characteristics. You continue using the HealthDecision website to assist you in visually demonstrating statistics about mammography screening. Since you typically follow USPSTF recommendations, you tell Nancy that you would recommend she begin screening at age 50. However, you also convey the ongoing debate about whether or not women at average risk for breast cancer in their 40s should begin screening. You ask Nancy to reflect on the harms and benefits of starting mammography screening, eliciting her values, concerns, and preferences. Nancy knows that going in for extra images or a biopsy would make her very nervous, however, she thinks waiting until she is 50 to get her first mammogram would give her even more anxiety. Nancy explains that she interacts often with the woman recently diagnosed with breast cancer at her son’s school and doesn’t think she’d be able to see her go through treatment without being reassured that she herself was cancer-free.
     You and Nancy Agree on a breast cancer screening plan. Nancy would like a mammogram in the near future. If the mammogram is normal, she states she would feel comfortable waiting until age 50 for her next mammogram.
     With this plan in place, you Assist Nancy in scheduling a mammogram for next month. You then Arrange a follow up appointment to discuss her results and revisit her screening plan. Her breast density on mammography may affect her overall risk of breast cancer and thereby affect her future screening plans.
Case study: Using the SHARE method to talk about lung cancer screening.
     On a busy clinic afternoon, you see Shari who is a 65 year old Caucasian woman with no chronic medical problems. You don’t see her very much because she doesn’t like to come in to the doctor. She is a current smoker with a 50 year pack year history of smoking. You see a note from your nurse saying that she would qualify for lung cancer screening.
     After a few minutes of greetings and catching up (you haven’t seen her in a year), you ask Shari if she would be willing to talk about lung cancer screening (Seek participation). She agrees to talk about it and you go over the process of lung CT, the sensitivity and specificity, what happens if they find something, the risks from a biopsy, the possibility of needing frequent follow up CTs if the radiologist finds a nodule. (Help your patient explore and compare options). You also bring up smoking cessation, but she is not ready to talk about it yet.
     Shari talks about not wanting frequent contact with the health profession, and the desire to live out her life without the worry about cancer. (Assess values and preferences.) She also remembers watching her mother die from lung cancer which was horrible. Her mother never quit smoking and didn’t go to the doctor until she could barely breathe. After a few more minutes going back and forth about the benefits and risks of screening, Shari decides to go ahead with lung CT. (Reach a decision with your patient). She also agrees to think about quitting smoking.
Together, you evaluate her decision and agree that for her, the benefits of screening outweigh the risks. You schedule a follow up visit in 2 months to talk more about smoking cessation.
Case study: Using the IAIS model to talk about prostate cancer screening.
     You are seeing Bob S., a 58 year old African American man who presents for a physical. He has well controlled HTN and hyperlipidemia. He had a PSA in the past that was in the normal range. He comes in with no complaints. His family history is negative for prostate cancer.
     You bring up the topic of screening for prostate cancer and ask him what he thinks about it. (Invite his perspective and concerns) He says he doesn’t know much about prostate cancer but his friend had surgery on his prostate and is now incontinent. He knows that he would do anything to avoid having a catheter.
     You acknowledge his concerns about possible complications from prostate surgery. You then instruct him about his increased risk of prostate cancer due to being African American. You talk about the accuracy of the PSA test and what a biopsy would be like if the PSA is elevated. You then talk about the fact that catching prostate cancer early can save lives but we never know which cancers are going to be aggressive so we end up treating everyone similarly. You talk about the risks from prostatectomy including incontinence and erectile dysfunction. You also talk to him about the different recommendations for and against routine screening for prostate cancer (USPSTF against, ACP and AUA for shared decision making).
     His initial decision is to NOT get a PSA but he wants to read more about it and talk to his wife.
You summarize your discussion in writing for him to take home and think about. You promise to bring the topic up again when he follows up for his HTN in 6 months.


     All primary care clinicians have the capacity to use shared decision making in clinical encounters. SDM provides a useful structure for discussing cancer screening options. Practicing clinicians will need to choose a model that works well for their practice.