Patients diagnosed with early-stage (I-II) non-small cell lung cancer (NSCLC) who undergo surgery experience substantially better outcomes than those who do not. Fiveyear survival rates range from 60–80% for resected stage I disease and from 30–50% for resected stage II disease, compared to 15% for non-resected stage I and II disease.¹ A multitude of previous studies have concluded that black patients are less likely than white patients to receive surgery,^2–9 likely contributing to documented disparities in NSCLC survival.² It is crucial to understand the current extent of, and factors underlying racial/ethnic differences in receipt of surgical treatment for early stage NSCLC, with the goal of informing strategies to improve the equity of care.

The pathway from lung tumor detection to surgery can be complex, requiring sequential coordination of multiple providers^10–12 who may be distributed across systems. Previous research has suggested that disparities in receipt of recommended lung cancer treatment may result at least in part from racial differences in patients’ ability to access specialty care services along this pathway. For example, black patients with NSCLC are less likely than white patients to be evaluated by a surgeon.¹³ This may be due in part to differences in where black and white patients receive their routine care, as primary care providers whose patient panels consist primarily of minorities report greater difficulties accessing high-quality specialty care for their patients.¹⁴

Patients who are members of integrated health care delivery systems experience more uniform access to local primary and specialty care services that are well-coordinated through the use of common information systems and referral networks.^15,16 Prior research suggests that, as a result, in integrated systems, cancer care delivery may be more equitable.^17–19 However, no studies have examined the role of uniform access to care in potentially reducing lung cancer treatment disparities by directly comparing racial/ethnic differences in initial treatment among members of an integrated health care delivery system to those among non-members. To address this gap, we analyzed data from the California Cancer Registry (CCR) on a contemporary and diverse cohort of patients diagnosed with early stage NSCLC. We hypothesized that racial/ethnic differences in the receipt of surgical resection would be minimized among members, compared to non-members, of an integrated health care system.

Our study examined disparities in receipt of guideline-recommended surgery among patients with early-stage NSCLC in Northern California from 2004 to 2011. We identified disparities among patients who were members of a fully integrated health care system and among patients who received their care elsewhere. Although the overall proportion of patients undergoing surgery was higher within KPNC, contrary to our hypothesis, access to integrated care (through KPNC membership) did not appear to attenuate disparities in surgery receipt. In particular, Black patients were substantially less likely than White patients to undergo surgery, regardless of access to integrated care.

To our knowledge, this is the first study to examine NSCLC surgery disparities in an integrated health care system other than the Veterans Affairs (VA) system. Because differences exist between veterans and the general population in terms of sociodemographic characteristics and health status,²⁴ the extent to which care patterns observed in VA-based studies extend to other settings is unclear. Our study confirms the conclusions of prior VA-based work, which documented Black-White disparities in surgical treatment for lung cancer,⁸ finding similar disparities in a different integrated system whose membership is largely representative of the insured population in its covered region. Our study is also the first to directly compare initial treatment for NSCLC between members and non-members of a fully integrated health care system living in the same geographic region.

Further, our analysis is distinctive in its use of contemporary data. Until now, the most up-to-date analysis of surgical disparities using SEER-Medicare data focused on patients diagnosed through 2005.²⁵ Outside of SEER-Medicare, the most recent data on treatment disparities in early stage NSCLC comes from a study of veterans diagnosed through 2007.⁸ Based on the results of our study, which included patients diagnosed through 2011, Black patients have continued to undergo recommended surgery at lower rates than White patients, suggesting a potential lack of progress in providing high-quality care for all lung cancer patients. As health care systems across the U.S. work to implement new recommendations for lung cancer screening,²⁶ rates of detection of early-stage, potentially resectable NSCLC are expected to increase considerably.²⁷ If tumors are increasingly detected at earlier stages, but not resected for all eligible patients, treatment and survival disparities may worsen. Therefore, it is critical to understand the underlying causes of racial differences in NSCLC treatment to inform interventions to close existing gaps.

Based on our results, the Black-White disparity in receipt of surgical resection appears to persist, even within an integrated system designed to provide uniform, coordinated access to needed services for its members. This finding is contrary to our hypothesis that disparities would be smaller, if not mitigated altogether, within KPNC as an “equal access” system, informed in part by prior research that found fewer disparities in colorectal cancer care and outcomes among members of integrated systems, compared to non-members in California. In general, however, evidence about the existence of disparities in integrated systems is mixed. Our results are more in line with those of VA-based cancer studies^8,13 and Kaiser Permanente-based studies²⁸ of other procedural services, which have concluded that disparities in care are not addressed by integrated system membership alone.

Specifically, in our main analysis of patients ages 21–80 at NSCLC diagnosis, observed Black-White disparities were very similar in magnitude among KPNC members and non-members. In a sensitivity analysis restricted to patients ages 65 and older, the Black-White disparity widened among KPNC members, but not among nonmembers. The magnitude of the disparity was greater among KPNC members only, given that a higher percentage of Black KPNC member versus non-member patients were aged 65 and older (65% vs. 47%) and that a much higher percentage of Black KPNC member versus non-member patients younger than 65 received surgery (84% vs. 64%), but a lower percentage of black KPNC member versus non-member patients aged 65 and older received surgery (55% vs. 63%). For the other racial/ethnic groups by age (<65, 65+), the percentage who received surgery was the same or higher in KPNC members than non-members. Explaining this variation in the proportion of younger and older Black patients receiving surgery within versus outside of KPNC represents an area for future investigation.

There are several reasons why disparities may be observed irrespective of the extent of access to integrated care. For example, others have suggested that racial differences in receipt of resection for NSCLC may result at least in part from differential eligibility for surgery, given prior reports that Black patients with cancer tend to have a greater comorbidity burden than their White counterparts.^29–31 However, empirical investigations of the relationships between race, comorbidity burden, and receipt of resection among veterans with early-stage NSCLC have concluded that the lower rates of resection among Black patients appear to result from factors other than racial differences in comorbidity.^2,8 Further, disparities in resection receipt are known to exist even among patients who are deemed healthy enough to undergo surgery, due to higher rates of refusal among Black patients, potentially explained by cultural differences in health beliefs and attitudes. Cykert and colleagues found that, among NSCLC patients, worse perceptions of physician communication and a lower certainty of lung cancer diagnosis were associated with lower likelihood of surgery receipt.³ These factors may stem from lower confidence in health care providers, a sentiment more prevalent among Black compared to White patients.³² In addition, prior studies have shown that Black NSCLC patients are more likely than White patients to hold misperceptions about lung tumor resection, namely, that surgery is associated with accelerated tumor spread.^33,34 Provider- and system-level factors may also contribute to disparities. For example, prior research suggests that health care providers’ treatment recommendations may be influenced by implicit biases. In particular, providers may not recommend potentially beneficial interventions to patients whom they expect to be nonadherent.³⁵

Data on racial/ethnic treatment differences for non-Black minorities are scarce, and our study builds upon the limited evidence base in this area. As previously reported by others,³⁶ we observed that, after adjustment, API and White patients were equally likely to undergo surgery; this was true of KPNC members and non-members. Also consistent with prior evidence,³⁷ we observed that, among non-members, Hispanics were less likely than whites to undergo surgery. This disparity did not exist among KPNC members. It is possible that, due to the smaller number of KPNC members relative to non-members, we lacked the statistical power to detect a significant Hispanic-White difference in our setting; however, the magnitude of the estimated Hispanic-White difference was also smaller among KPNC members (2% among members ages 21–80; 8% among members ages 65–80) than it was among non-members (7% among non-members ages 21–80; 13% among non-members ages 65–80). It may be that Hispanic KPNC members are systematically different from Hispanic non-members in ways that may affect their access to and use of recommended treatment, namely, with respect to SES or education. Unfortunately, our study lacked access to individual-level information about these factors.

The results of our study should be interpreted in the context of some additional limitations. Because we used data from the CCR, which does not contain information about patients’ comorbidities, pulmonary function measures, or functional status, we were unable to adjust for patients’ overall health status, which may affect their candidacy for surgery. To the extent that Black patients are at higher risk for comorbid conditions, comorbidity may have been an important omitted variable, that if included, may have somewhat attenuated the Black-White disparities we observed. Given prior evidence that Black-White differences in comorbidity burden do not entirely explain treatment disparities,^2,8 it seems unlikely that accounting for comorbidity burden would have substantially altered our estimates. We attempted to address this potential limitation by conducting a sensitivity analysis excluding patients who, according to the CCR, had a documented contraindication for surgery; this exclusion did not affect our results. In addition, the CCR only captures data on initial treatment, occurring up to six months after diagnosis. Therefore, it is possible that patients in our cohort classified as not receiving surgery did, in fact, receive surgery. However, previous research suggests that, on average, definitive surgery for NSCLC occurs before six months post-diagnosis.^38,39 Finally, the CCR contains limited information about insurance status. Therefore, we cannot be certain that NSCLC classified as non-members of KPNC did not receive some level of integrated care elsewhere. Given that KPNC is by far the largest and only fully integrated system in Northern California, covering a third of the region’s insured population, we do not expect this potential limitation to have substantially impacted our findings.²⁰

We observed that Black-White disparities in receipt of resection for early-stage NSCLC were similar in magnitude for integrated system members and non-members. Our findings suggest that factors not strictly related to access to surgical care may underlie the disparities observed in our and other studies. Future research should focus on the roles of other factors, especially modifiable factors (e.g., patient-provider communication), in explaining disparities for treating early stage NSCLC, with the goal of informing interventions to overcome them.