Overall, NCI-Cancer Center attendance among patients with breast, lung, colorectal, or prostate cancer was only 7.3% of the SEER-Medicare population. The most influential determinants of NCI-CC attendance were travel-time, place of residence, particularly for African Americans, and predominant type of care before diagnosis. Urban African-Americans were more likely to attend an NCI-Cancer Center compared to urban Caucasians. Cancer patients whose care in the six months prior to diagnosis was predominated by generalists rather than specialists were less likely to attend an NCI-Cancer Center. Disease-specific factors were also important to attendance, including cancer site, stage at diagnosis, and the presence of comorbidities. Individuals diagnosed with lung cancer were more likely to attend than those diagnosed with breast, colorectal, or prostate cancers. For all cancers combined, later stage at diagnosis and the presence of fewer comorbidities were both positively associated with NCI-Cancer Center attendance. Factors contributing to these referral patterns may include provider referral patterns or patient referral preferences. The relative capacity to care for cancer patients in a given community is also likely to be important.
This study does not examine the outcomes associated with NCI-Cancer Center care, which may differ substantially by type of cancer, stage, or by the specific Center. Further research into the patient benefits of different locations of cancer care would help establish benchmarks that could guide further growth and improvement efforts in oncology services.
In previous studies, greater travel-time, travel distance, and rural residence each have been associated with decreased geographic access to health care3,8,12,25–28
. Recent evidence suggests that utilization of specific treatments is related to travel distance8,25,28
. Our results indicate that longer travel-time is associated with decreased utilization of the most specialized cancer care settings. Our findings are consistent with a previous study demonstrating that referral of lung cancer patients to university hospital Cancer Centers in New England was significantly lower with greater travel distances12
. Our results suggest that travel-time did not impact overall receipt of cancer care, but greatly influenced attendance at NCI-Cancer Centers. Thus perhaps most patients do not travel far from their local/regional health care facilities, and a requisite for NCI-Cancer Center attendance is proximity. In a previous study, we have shown that over 42% of the U.S. population lives within an hour of an NCI-Cancer Center17
; thus a sizable number of individuals may be influenced by proximity to these centers. Since proximity to NCI-Cancer Centers varies by demographic groups17
, the impact on specific subpopulations should be considered, particularly given the seemingly low attendance (7.3%) of Medicare beneficiaries in this cohort. Community programs to promote travel assistance to cancer care facilities may be warranted in rural areas.
Race/ethnicity was important to NCI-Cancer Center attendance in this study. African-Americans living in urban locations (86.6% of African-Americans in our study population) were ~1.5 times more likely than their Caucasian counterparts to attend an NCI-Cancer Center. This result is consistent with a previous study that examined surgical utilization at NCI-Cancer Centers, in which African Americas received more surgical procedures than Caucasians2
. There are at least two explanations for this pattern: 1. African-Americans may be more likely to use urban-based hospitals, and 2. African-Americans are more likely to use teaching-not-for-profit hospitals, which would include most NCI-Cancer Centers, which also are located in urban areas. There is currently little empirical support for the first explanation. The second explanation is supported by a study demonstrating a 75% greater probability of using a teaching hospital among African-Americans compared to Caucasians13
. Interestingly, the observation that African-Americans are more likely to utilize NCI-Cancer Centers than Caucasians occurs at the same time that studies have documented inferior cancer care for African-Americans compared to Caucasians7,29–31
. What is not known is how these treatment disparities are impacted by institution type. Several studies suggest that treatment and outcomes vary more by place of care than by race/ethnicity10,32
Referral patterns are likely to play a role in NCI-Cancer Center attendance. We found a lower likelihood of attendance for individuals whose care prior to cancer diagnosis was predominantly from generalist physicians. One explanation is that specialists may be more likely to have referral networks to tertiary specialists or sub-specialists compared to generalists. Another possibility is that generalist providers may have more established community-based partnerships with oncologists at specialized centers; thus, their patients have less need to travel to an NCI-Cancer Center. This result was unlikely to be due to rural residence, local oncologist supply, or the distribution of NCI-Cancer Centers within SEER regions, since we adjusted for these variables
Stage at diagnosis and number of comorbidities had different associations with NCI-Cancer Center attendance. Later stage was associated with a higher chance of NCI-CC attendance. Because we saw a greater likelihood of African-American attendance, and evidence shows later stage of diagnosis in this group33,34
, we examined the relation between stage and race in our study population, and found no evidence for an interaction in relation to attendance. It is possible that patients with late stage disease attend NCI-Cancer Centers to gain maximal clinical benefit in a context of poor prognosis.
On the other hand, we found that an increasing number of comorbidities were associated with a lower likelihood of NCI-Cancer Center attendance. A plausible explanation is that these individuals are the most ill or incapacitated and may rely on the most proximal, convenient health care resource. Also, it is possible that patients with more comorbidities have greater frequency and continuity of contact with primary care providers, and thus rely on established relationships in their communities to a greater extent.
Several limitations are noteworthy in this study. Some racial groups had too few individuals attending NCI-Cancer Centers in the SEER regions to reliably include in models. Also, because we based our analyses on Medicare claims, these findings may be generalizable only to cancer patients older than 65 years. Further, as claims data are derived for billing, coding biases may be present. We based this study on claims data to provide a population-based perspective, and, thus, were unable to explicitly examine patient or provider preferences, individual-level income, number of cancer care facilities available, availability of transportation, and physician referral patterns.
We developed a cancer center attendance definition a priori which we tested empirically within our study population. We accounted for NCI-Cancer Center attendance based on surgery, but further exploration of types of services utilized at NCI-Cancer Centers seems warranted, since patient utilization may range from a single, second-opinion visit to the totality of care. Finally, evidence for better quality or outcomes at NCI-Cancer Centers is incomplete; thus the relative costs and benefits of attendance in not known. Only with this information can primary care clinicians assist individual cancer patients in their own referral decisions
In conclusion, 7.3% of Medicare beneficiaries with lung, breast, colorectal, or prostate cancer attended an NCI-Cancer Center. Currently, our understanding of appropriate utilization of these specialized centers is incomplete, and may vary by cancer site and regional supply of oncology services. NCI-Cancer Center attendance is significantly influenced by travel-time, utilization of primary care prior to diagnosis, and status as an urban African-American. These findings have implications for coordination of primary and hospital-based care, and for resource allocation of the most specialized cancer care, including access to outreach oncology clinics.