Clinical Investigation
Cartographic Mapping and Travel Burden to Assess and Develop Strategies to Improve Minority Access to National Cancer Clinical Trials

Presented in part as a poster abstract presentation at the National Cancer Institute–American Society of Clinical Oncology Cancer Trial Accrual Symposium, April 29-30, 2010, Bethesda, MD.
https://doi.org/10.1016/j.ijrobp.2015.06.041Get rights and content

Purpose

To assess how accrual to clinical trials is related to US minority population density relative to clinical trial site location and distance traveled to Radiation Therapy Oncology Group (RTOG) clinical trial sites.

Methods and Materials

Data included member site address and ZIP codes, patient accrual, and patient race or ethnicity and ZIP code. Geographic Information System maps were developed for overall, Latino, and African American accrual to trials by population density. The Kruskal-Wallis test was used to assess differences in distance traveled by site, type of trial, and race or ethnicity.

Results

From 2006 to 2009, 6168 patients enrolled on RTOG trials. The RTOG US site distribution is generally concordant with overall population density. Sites with highest accrual are located throughout the United States and parts of Canada and do not cluster, nor does highest minority accrual cluster in areas of highest US minority population density. Of the 4913 US patients with complete data, patients traveled a median of 11.6 miles to participate in clinical trials. Whites traveled statistically longer distances (12.9 miles; P<.0001) to participate, followed by Latinos (8.22 miles) and African Americans (5.85 miles). Patients were willing to drive longer distances to academic sites than community sites, and there was a trend toward significantly longer median travel for therapeutic versus cancer control or metastatic trials.

Conclusions

Location matters, but only to a degree, for minority compared with nonminority participation in clinical trials. Geographic Information System tools help identify gaps in geographic access and travel burden for clinical trials participation. Strategies that emerged using these tools are discussed.

Introduction

Approximately 1.7 million new cancer cases were diagnosed in 2014 (1). Randomized cancer clinical trials (CCTs) conducted by the National Cancer Institute (NCI) National Clinical Trials Network (NCTN) provide much of the evidence for clinical guidelines and standards of care (2). Enrollment in clinical trials, independent of the experimental treatment, has a positive effect on patient-centered outcomes, owing to high-quality care, quality assurance of treatment modalities, fidelity to treatment protocols, and increased patient surveillance (3). In one study, patients who traveled more than 15 miles to participate in a CCT had a third of the risk of death compared with patients who traveled less distance. Further, with every 10 miles that a patient traveled, the risk of death decreased by 3.2%, even after adjusting for potential “fitness to travel indices” (eg, age, income, tumor stage and site, performance status, etc) (4).

Thus, for reasons including representation, generalizability, and quality of care, all patients should have access to clinical trials. Yet, despite national initiatives to increase the enrollment of racial and ethnic minorities into CCTs, such as the Minority Based Community Clinical Oncology Programs (MB-CCOPs) and the NCI AccrualNet, participation by Latino and African American (AA) populations remains low relative to their representation in the US population and to the burden of cancer they bear.

Latinos comprise approximately 16.9% of the population (5). Latinos have lower incidence and mortality rates than white Americans for the most common cancers; however, Latinos are more likely to be diagnosed at a more advanced stage. Additionally, cancer mortality rates are 22% higher among US-born Latinos than their foreign-born counterparts who have immigrated to the United States (6). African Americans comprise 13.1% of the total US population (7) and have the highest death rate and shortest survival of any racial and ethnic group in the United States for most cancers (8). The causes of these inequalities in cancer outcomes among different races or ethnicities are complex and most likely due to social and economic disparities more than biologic differences (8).

Cancer clinical trial accrual for all adult cancer patients is only approximately 3% to 8%, and white patients make up the majority of trial participants (85.6%) (9). Latinos and AAs constitute a much lower percentage (5.6% and 8%, respectively) (9). Research has shown that with equal access Latinos and AAs seem to have similar CCT participation rates as whites (9). Access is multifactorial; however, logistical barriers that may have significant influence such as geographic location and travel distance to participating site have received only modest attention. Thus, the purpose of this project was to examine how accrual to CCTs is related to US minority population density relative to clinical trial site location and distance traveled to institutions that were members of the NCI-sponsored Radiation Therapy Oncology Group (RTOG) clinical trials network. In addition, distance traveled was also assessed: it is of particular importance in radiation therapy (RT) CCTs because daily travel for 4 to 8 weeks is often required.

Section snippets

Methods and Materials

After institutional review board approval, address and ZIP codes of RTOG academic full and affiliate members and their satellite sites, along with Community Clinical Oncology Program (CCOP) members and their component sites, were obtained. Higher levels of patient accrual to CCTs are required for full members, and they may count their health system–owned satellite site accrual as a part of their total accrual. Academic sites may also have affiliates from separate health systems, which accrue at

RTOG sites and overall patient accrual

From 2006 through 2009, 6168 individuals were enrolled on an RTOG trial (1234 on phase 2 studies and 4735 on phase 3) from 400 sites. Patients enrolled by Canadian sites accounted for 17.8% accrual over this time period.

For the distance traveled analysis, 4913 US participants had complete information (ZIP code and race or ethnicity), with 4072 treated on a CCT at full, affiliate, or satellite sites and 841 at CCOP or component sites. Of these, 4369, 450, and 94 patients, respectively, were

Cartographic mapping of clinical trials accrual

The RTOG site distribution and levels of participant accrual generally appear concordant with US population density. The visual maps help identify several gaps in patient accrual not as readily recognized through traditional tables and graphs. Location gaps are easily identified where there are fewer RTOG sites in higher-density Latino regions. For example, mapping indicates that the highest Latino accruing sites to RTOG trials are predominantly not in the higher-density geographic Latino

Conclusion

Geographic Information System mapping has helped identify geographic patterns of overall and minority CCT accrual, as well as high-density minority population areas without RTOG member sites. This will help us strategically identify RT sites for outreach efforts as new partners in minority-enriched locations, to facilitate equal access to state-of-the-art CCTs. Mapping also identified high-minority RTOG clinical trial accrual in lower minority dense sites, which would not have been easily

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This study was supported by the Pennsylvania Commonwealth Universal Research Enhancement Program (ME-02-149), Radiation Therapy Oncology Group grant U10 CA21661, and Community Clinical Oncology Program grant U10 CA37422 grants from the National Cancer Institute.

Conflict of interest: S.L.P. reports grants from the Pennsylvania Commonwealth Universal Research Enhancement Program (ME-02-149) during the conduct of the study.

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