Elderly women, blacks, Asians, Pacific Islanders, and Hispanics are all still underrepresented in lung cancer clinical trials, while gender- and age-based disparities have improved, according to a report published online in Journal of Clinical Oncology.

Herbert H. Pang, PhD, of the Li Ka Shing Faculty of Medicine, Hong Kong, and his coauthors noted that enrollment disparities in cancer clinical trials have existed for many years, with previous research showing underenrollment of the elderly, women, blacks, and racial and ethnic minorities.

In this study, they analyzed data from 23,006 participants in National Cancer Institute lung cancer trials, and 578,476 patients with lung cancer from the SEER registry (J Clin Oncol. 2016 Sep 19. doi: 10.1200/JCO.2016.67.7088 ).

When they compared the proportion of each subgroup in the trial population with the proportion in the U.S. lung cancer population over time, they noted consistent underrepresentation of blacks, Asian/Pacific Islander, and Hispanic patients across the entire study period.

The enrollment disparity for patients aged 70 years or older with non–small-cell lung cancer improved significantly from 1990 to 2012, but while there has been an increase in the proportion of elderly patients with small-cell lung cancer in the U.S. population from 1990 to 2012, the proportion of elderly patients in trials for small-cell lung cancer remained static.

The authors suggested that this may have been the result of local enrollment patterns for the mostly smaller, phase II trials in small-cell lung cancer, but also the fact that the therapies investigated for small-cell lung cancer may have posed a greater risk of treatment toxicity, which would limit the enrollment of older patients.

Significant improvements were seen in the proportion of women enrolled in lung cancer trials, with the enrollment gap between the genders closing in 2012, although elderly women were still underrepresented in lung cancer clinical trials.

“These findings suggest a beneficial effect of the NIH Revitalization Act of 1993 that mandated the inclusion of women and minorities in all NIH-funded research,” the authors wrote. “However, other important enrollment disparities, especially for older patients with SCLC, elderly women, and racial/ethnic minorities, continue to persist and require ongoing work to eliminate underrepresentation in lung cancer treatment trials.”