In this large, population-based cohort of individuals with recently diagnosed lung or colorectal cancer, we observed that characteristics of the decision itself were associated with patients' roles in decisions. Although absolute differences were relatively modest, we found that variability in the strength of evidence influenced patients' roles; the highest rates of shared control were for decisions with evidence for the treatment, the highest rates of patient control occurred when evidence of benefit was uncertain, and the highest rates of physician control occurred when there was no evidence to support the use of the treatment. We also observed that patients making more preference-sensitive decisions (ie, treatments for metastatic cancer) were more likely than others to describe a shared-control or physician-controlled role and were less likely to report the decision was patient controlled. Finally, we found that patients' roles in decisions differed by treatment modality, with more patient control for chemotherapy decisions and more physician control for surgery and radiation decisions.
Consistent with our hypothesis, patient control was high when the evidence about a treatment is uncertain; thus, patients' preferences should be important. It may be that physicians encourage patients, either explicitly or indirectly, to assert more control in such settings. Similarly, the high rates of shared control when there is good evidence for a treatment's effectiveness suggests there is ample discussion between the physician and patient about the evidence and how to respond. Nevertheless, we also expected high rates of shared control for decisions with no evidence for (or evidence against), and we instead found high rates of physician control (compared with decisions with evidence for or uncertain evidence).
In patients with metastatic cancer, high-level evidence shows that treatment offers at best only modest benefits and is accompanied by toxicity in essentially all patients. As a result, there is near uniform consensus that decisions about these treatments should reflect patients' preferences. Surprisingly, we observed lower rates of patient control and higher rates of physician control for these inherently preference-based decisions. It is possible that patients with more severe illness want less involvement in their decisions.12
It is also possible that patients do not want to own decisions about therapies that cannot cure them and that the lack of curative treatments is perceived by patients as a loss of control over their cancer and, by extension, a loss of control over the decision. Our finding of more physician control for decisions with no evidence for (or evidence against) the treatment supports this possibility. In a prior study, women who perceived having a choice about breast cancer treatment had higher levels of shared decision making than women who felt they had no choice.14
It may be that the lack of good choices translates to feeling not involved in the decision. An alternative explanation is that patients may lack a vested interest in treatments that cannot cure them and may make a purposeful decision to not exercise control over decisions regarding their incurable cancer.
We observed some variation in reported patient role in decisions on the basis of treatment modality, with the highest rates of patient control for chemotherapy decisions and higher rates of physician control for radiation and surgery decisions. These findings suggest that oncologists may be more inclined to engage patients in decisions than surgeons and radiation oncologists.
Married patients were more likely than unmarried patients to report a shared role and were less likely to report physician control of decisions; spouse accompaniment to consultations may result in more shared decision making.14
Our finding that patients with better prediagnosis health status were less likely to report physician control of decisions and more likely to report patient control may reflect greater focus on maintaining health status and addressing illness. In addition, patients with poorer health status may be perceived by their physicians as poorer candidates for some treatments and thus feel they were not involved in the treatment decisions.
The strengths of this study include a large, population-based cohort of patients with cancer from various geographic areas in the United States and a rich set of potentially relevant variables, including information about role in treatment for several treatment modalities. In addition, the demographic and clinical characteristics of the full CanCORS patient cohort are similar to national estimates.26
However, our findings should be interpreted in light of several limitations. First, patients surveyed 3 to 6 months after diagnosis may have had difficulty remembering the role that they played in a specific decision, or their perceptions of the role they played may have changed.6
In addition, other research suggests that patients' perceptions of involvement do not always match other measures of their involvement.6,27
Second, our depression measure was collected at the time of the survey, not when decisions were made, and is not sensitive to capturing emotional distress short of major depression. Third, as with all survey research, respondents may have differed from nonrespondents; nevertheless, response rates were relatively high among patients reached. Fourth, we did not verify that physicians were aware of the evidence (or lack thereof) and communicated it appropriately, nor did we have information about physician's communication style or other details about the decision-making process. Research suggests that surgeons' solicitation of patients' treatment preferences is associated with patient participation in treatment decision making for women with breast cancer.28
Methods to better understand physician's decision styles with their cancer patients and survivors have recently been developed.29
Finally, many of our patients were age ≥ 70 years, and strong clinical trial evidence in those patients are lacking, which makes it difficult to categorize strength of evidence. Nevertheless, our findings were similar when we restricted the cohort to individuals age ≤ 70 years.
In conclusion, characteristics of decisions themselves were associated with patients' roles in decisions. Specifically, patients making decisions about treatments with strong evidence had high rates of shared control, and we observed high rates of patient control when evidence was uncertain. However, patients making decisions about treatments for which no evidence supports benefit and patients making more preference-sensitive decisions, such as those for metastatic cancers, tended to be more physician controlled than other decisions, which suggests that patients may not want to take responsibility for making decisions that will not lead to a cure. Better strategies for engaging patients in decisions may be needed when there is no evidence to support benefit of a treatment or when patients have terminal illnesses that cannot be cured.