In a nationally representative cohort of patients with stage IV breast, colorectal, lung, and prostate cancer, we found that essentially all patients undergo frequent high-cost imaging procedures, including CT, MRI, PET, and NM, as defined by MedPAC. Imaging occurs throughout the continuum of these patients’ cancer care, and rates of imaging have steadily increased during the study period, from January 1995 to December 2006.
Unlike previous studies (7
), the inclusion of SEER-provided clinical data allowed us to examine the delivery of care prospectively from diagnosis of stage IV cancer until death or the end of follow-up (3 years after diagnosis); because survival is understood to be limited in stage IV disease, our observations cannot be attributed to an inability to anticipate death, which is often a limitation of retrospectively designed end-of-life studies (16
). We also build upon previous work by defining clinically relevant phases of care, as described by others in the study of cancer (14
), and characterizing use of imaging within each. It may be argued that the last month of life is not definitively identifiable in a prospective manner. Despite this fact, our findings that utilization varies with both phase of care and length of survival seem to indicate that patient and physician decision-making is influenced by perceived survival. Indeed, physicians’ predictions of survival are highly correlated with actual survival (Spearman rank correlation [r
] = 0.6, P
< .001) in terminally ill cancer patients (17
Our study has a few limitations. As previously discussed, no ICD-9 codes exist for PET scans, thus all PET claims in the inpatient file without a corresponding claim in the physician file were necessarily misclassified as NM studies. However, the effect was likely minimal, as only 1.1% of NM claims in our final dataset originated from the inpatient file. Additionally, it is not possible to determine the intent behind the procedures ordered, a known limitation of using administrative data that impacts interpretability with regards to appropriateness of high-cost imaging use. If one assumes that the rationale behind the majority of imaging during the diagnostic period is staging, the higher absolute rate of scanning in the stage IV population may reflect the ability of advanced imaging to upstage cancer diagnoses. Beyond diagnosis, scans in stage IV patients likely represent a mixture of acute symptom management, evaluations of disease progression, and assessments of treatment effect. Because scans help clinicians determine whether a change in (or cessation of) treatment is indicated, the expanding use of advanced imaging in stage IV disease is likely a manifestation of the increasing number and types of treatment options available to these patients (6
Although imaging can be important in guiding such decisions, the impact of imaging on care is intimately tied to the effectiveness of the care it drives. Studies suggest that patients with cancers unresponsive to chemotherapy continue to receive it (19
) and the benefit of successive lines of chemotherapy is small, even in typically responsive tumors (20–22). For the four tumor types we studied, survival in incident stage IV disease has changed modestly if at all over the past one or two decades (23–26
); although treatment may be changing (and imaging with it), the natural history of metastatic disease is not. As systemic treatments evolve, the role of imaging must be continuously evaluated.
Further research is needed to better characterize the appropriate role of advanced imaging in the setting of metastatic disease and thus to support physicians in the evidence-based care of these patients. Currently, few guidelines attempt to define the appropriate role of imaging in patients with advanced disease, and those that do largely reflect expert opinion. Routine use of imaging is recommended only in patients with colorectal cancer metastatic to the liver or lung; in such patients, the National Comprehensive Cancer Network (NCCN) advises a CT or MRI every 2 months after initiating chemotherapy to reevaluate for resectability, followed by every 2–3 months during palliative chemotherapy if conversion is not accomplished (27
). In stage IV breast (29
), lung (31
), and prostate cancer (32
), the guidelines either do not specify parameters for testing or advocate use only as indicated by symptomatology.
Despite these recommendations, we found that the vast majority of patients with breast, lung, and prostate cancer undergo imaging after diagnosis at rates similar to (or higher than) that of the colorectal subset. Such discretionary decision-making, ie, the “gray” area where recommendations are equivocal or nonexistent, is known to drive higher healthcare spending (33
). Indeed, we observed a great deal of variability in the use of high-cost imaging, with patients in the top 10% receiving at least one scan per month during continuing care and at least three in their last month of life. Overuse is explicitly addressed only once in the guidelines—in a recommendation against PET monitoring for stage IV colorectal disease (27
). Nevertheless, like their breast and lung cancer counterparts, for whom no such directives exist, nearly one in four colorectal cancer patients had a PET scan during continuing care.
In contrast, over the period we studied, national guidelines defined a circumscribed role for imaging in the surveillance of patients with early-stage breast, lung, colorectal, and prostate cancer after treatment, in response to evolving evidence of its limited utility in these settings. Routine advanced imaging is now recommended only in lung (34
) and select colon cancer patients (those who are at high risk for recurrence and are candidates for resection) (27
). Correspondingly, in our cohort of patients with stage I and II disease, the frequency and intensity of imaging outside of the diagnostic period declined over time.
Finally, as the increased national focus on comparative- and cost-effectiveness research and patient-centered outcomes reaches end-of-life care, quality of life must be among the primary outcomes assessed. Imaging, although it often leads to (appropriate) palliative measures, may also distract patients from focusing on achievable end-of-life goals, require them to spend more of their limited time in medical care settings, and/or provoke anxiety (37
). These procedures represent a costly, yet underappreciated and understudied aspect of care in this vulnerable population. As our approach to their care evolves, it will be important to define the role of high-cost imaging to ensure that the maximum value, in terms of both societal resources and patient quality of life, is achieved.