Ethnic minorities, older adults underrepresented in lung cancer clinical trials

Older patients with small cell lung cancer and minority patients remained underrepresented in lung cancer clinical trials conducted between 1990 and 2012, according to the results of a meta-analysis.

Underrepresentation improved during this period for women with lung cancer and older patients with non–small cell lung cancer, results showed.

Lung cancer is the primary cause of cancer death in the United States. The majority of patients have a median age of 70 years at diagnosis.

“Despite the growing population of older adults in the United States and worldwide, many cancer treatments are primarily studied in younger, fit patients, with results extrapolated to older adults,” Xiaofei Wang, PhD, associate professor of biostatistics and bioinformatics at Duke University Medical School, and colleagues wrote. “In addition, women and racial/ethnic minorities are underrepresented in clinical trials, prompting the NIH Revitalization Act of 1993, which mandated the inclusion of women and minorities in all NIH–funded research.”

The analysis included data from 210 NCI–sponsored lung cancer trials conducted in the United States, representing 23,006 adult patients, as well as 578,476 patients with lung cancer in the SEER database — representing the U.S. lung cancer population — during the same period.

Wang and colleagues calculated annual percentage changes in subgroups of patients over time enrolled in trials compared with the total U.S. population of patients with lung cancer in the SEER registry.

The researchers observed improvements in representation of women and older patients over time. The annual percentage changes among older patients were 3.27 (95% CI, 2.21-4.34) for trial participants and 0.72 (95% CI, 0.51-0.93) for SEER patients. Among women, the annual percentage changes were 1.65 (95% CI, 1.31-2) for trial participants and 0.8 (95% CI, 0.71-0.9) for the SEER registry.

Researchers then calculated enrollment disparity differences — or the absolute difference between the estimated subgroup proportion among the U.S. lung cancer population and trial participants — and enrollment disparity ratios, or the estimated subgroup proportion among the U.S. lung cancer population divided by the subgroup proportion of trial participants. These two measures showed enrollment disparities in absolute and relative terms, according to the researchers.

Although the enrollment disparity for older patients improved during the study period (P = .02 for parallelism), the enrollment disparity difference for the most recent study period (2010-2012) was 0.24 (95% CI, 0.21-0.26), and the enrollment disparity ratio was 1.77 (95% CI, 1.62-1.95).

The enrollment gap for women closed by the most recent study period (enrollment disparity difference, 0.03; enrollment disparity ratio, 1.07).

When researchers evaluated elderly patients by lung cancer type, they observed greater enrollment trends in older patients with NSCLC (P = .004 for parallelism). However, there was no change over time in enrollments of older patients with small cell lung cancer (annual percentage change, –0.2; 95% CI, –1.29 to 0.91), despite an increase of patients with small cell lung cancer in the SEER population (annual percentage change, 0.32; 95% CI, 0.06-0.58; P = .02).

Racial and ethnic minorities also did not experience a significant increase in representation during the study period. Disparities persisted among black patients at all periods; for the period from 2006 to 2009, black patients had an enrollment disparity difference of 0.04 (95% CI, 0.03-0.05) and an enrollment disparity ratio of 1.58 (95% CI, 1.38-1.85).

Individuals of Asian/Pacific Islander and Hispanic descent experienced similar trends. The researchers could not observe clear trends for patients of American Indian/Alaskan Native heritage due to small sample sizes.

The researchers acknowledged study limitations, such as the inclusion of only NCI–sponsored trials and the lack of data on certain ethnic minorities.

Because barriers specific to older adults have been noted in previous research, Wang and colleagues suggested elderly-specific trials as a solution. They also recommend comprehensive geriatric assessments to identify older adults who are fit and able to tolerate trial participation and cancer treatment.

“Our study also highlights the need to investigate more refined subgroups, such as cancer subtypes and extent of disease, to better understand enrollment disparities and allow policy makers to prioritize their goals,” Wang and colleagues wrote. “In the era of personalized and precision medicine, not only must we identify subgroups that would benefit from therapies the most, but our study designs and research policies should also target appropriate subgroups of individuals to yield more effective outcomes and continue to close the enrollment disparity gap.” – by Cameron Kelsall

Disclosure: Wang reports no relevant financial disclosures. Please see the full study for a list of all other researchers’ relevant financial disclosures.