Ethnic Disparities in Imaging Utilization at Diagnosis of Non-Small Cell Lung Cancer

Rustain L. Morgan, MD, MS; Sana D. Karam, MD, PhD; Cathy J. Bradley, PhD


J Natl Cancer Inst. 2020;112(12):1204-1212. 

In This Article


One-fourth of patients with newly diagnosed NSCLC do not receive PET imaging. Within this sample, blacks and Hispanics had a statistically significantly lower rate of PET imaging compared with non-Hispanic whites for every stage. This discrepancy was greatest for stage IV squamous cell carcinoma, where 75% of non-Hispanic whites received a PET compared with only 58% of blacks and 62% of Hispanics. The potential impact of our findings on changing practice patterns and improving outcomes is considerable.

Ensuring equity in the US health-care system is a top priority for the National Academy of Medicine but remains a practical challenge to implement.[14] We identified PET imaging as a potential contributing factor to racial differences in NSCLC survival. Improving the rate PET imaging is a targetable intervention with considerable supporting evidence of its benefit.[4,10,15–17] For example, PET imaging improves staging, as shown by a prior study where PET increased the stage of disease in approximately 10% of patients.[11] Blacks and Hispanics are diagnosed at later stages compared with non-Hispanic whites, which, given our results of PET use differences, suggests prior reports may underestimate racial and ethnic differences in stage at diagnosis.[1,11,18] Our findings suggest that equitable use of PET imaging may more accurately stage the disease, leading to more appropriate guideline-concordant care, and ultimately reduce the NSCLC survival gap currently reported between ethnic groups.

Prior studies identified an association between race and PET usage in NSCLC.[19] A Veterans Health Administration multi-site, prospective, observational study (CanCORS) from 2003 to 2005 showed 13% less PET usage in non-whites and Hispanics. Although this study drew from only four geographic regions and Veteran Health Administration patients are more likely to be from racial and ethnic minority groups, it does demonstrate that the issue is found outside of the Medicare population.[20] In addition, these data were published nearly a decade ago, yet the disparate trends in PET usage continue and are independent of differences in income, education, insurance coverage, or health-care setting. These data collectively suggest that factors inherent to medical practice may explain why PET was used less frequently in insured blacks and Hispanics.

Our data showed that patients receiving treatment at NCI-designated centers were more likely to undergo PET imaging at diagnosis at a rate almost 10% higher than teaching or community hospitals. This supports previous research demonstrating better adherence to practice guidelines for NCI centers vs other hospitals.[21] The commitment to treatment guidelines may also contribute to the survival benefits previously reported for patients receiving care at a NCI-designated center.[22,23] Although our study supports these prior reports, it is important to note the three groups had a similar rate of use at NCI centers. The differences in PET use and survival cannot be explained by differences in treatment location.

Our findings are relevant to clinical practice, both in support of current guidelines and in confronting the problem of considerable racial and ethnic disparity. Health-care providers who stage patients with newly diagnosed NSCLC should be aware not only of the impact of PET imaging and its association with improved CSS and OS but also of the racial and ethnic gap in PET usage. Although the cause for the disparity in imaging use for blacks and Hispanics is unknown, one factor that may contribute to this difference is unconscious or institutional bias. A prior systematic review found 35 studies demonstrating implicit bias in health-care professionals, with 42 studies showing a statistically significant positive correlation between the level of implicit bias and lower quality of care.[24] The simple step of being aware of potential unconscious bias can influence clinicians' delivery of care to patients.[25]

Recently, PET overuse has been a subject of controversy. A 2016 study using lung and esophageal SEER-Medicare datasets reported no change in CSS when PET is used to evaluate tumor recurrence.[26] These data triggered a debate in the literature questioning the overusage of PET imaging in these disease subsites. Our data specific to NSCLC and the collective published body of evidence, however, show that PET usage for diagnosis and treatment management is associated with improved CSS.[10,11,15–17] It is important to note that the Centers for Medicaid and Medicare Services continues to support PET usage for staging and treatment management.[27] Additionally, multiple international guidelines, including the NCCN, European Society for Medical Oncology, Pan-Asian-adapted Clinical Practice Guidelines, and the American College of Radiology Appropriateness Criteria, support the usage of PET at diagnosis of NSCLC.[4,6–8] This level of support is due to numerous prior studies demonstrating PET imaging often alters patient management or serves as a prognostic marker for future outcomes.[10,11,15–17] Our results show PET with or without CT imaging is associated with statistically significant improvement in survival, for all stages, compared with patients imaged with CT alone, supporting prior studies.

Our study has limitations. Our analyses were based on SEER registry data in a Medicare fee-for-service population with required coverage 12 months before and following diagnosis, decreasing our sample and limiting generalizability to all Medicare patients. Application to younger patients or patients with other forms of insurance (or uninsured) requires further study. By limiting the sample to patients who underwent PET with CT imaging during the diagnostic period, we are biasing toward the null. Improved disease detection by PET could lead to stage migration and spurious improvement in survival rates. SEER registries are reported to have greater economic disadvantage and greater racial and ethnic diversity, which may limit the results' generalizability to the national population.[28] Although our multivariable analysis controlled for numerous independent variables such as age, stage, sex, and facility, there may be unobservable characteristics that also affect the disparate usage of PET.[19]

Blacks and Hispanic patients with newly diagnosed NSCLC are imaged with PET at a lower rate than their non-Hispanic white counterparts. These findings may contribute to poorer outcomes for racial and ethnic minorities but also suggest a path forward to combat racial inequality in health care. Further studies to identify underlying causes of this racial and ethnic disparity in PET imaging are warranted.