Generalizability of Randomized Controlled Trials in Rectal Cancer

The generalizability of outcomes from randomized controlled trials (RCTs) in oncology is a frequent concern. Given the prevalence and multidisciplinary management of rectal cancer, understanding the generalizability of rectal cancer RCTs is critical to surgical oncologists.

An exhaustive literature review identified 100 non-metastatic rectal cancer RCTs published in English over the past 10 years investigating surgery, chemotherapy, or radiotherapy. In order to evaluate the representativeness of these RCTs compared to the USA and each continent's rectal cancer populations, demographic characteristics were stratified by surgical versus chemoradiotherapy (CRT) trial and by continent then compared with the National Cancer Database and CANCER TODAY using chi-squared and Welch's t-tests.

Of the 100 trials identified, 65% enrolled significantly younger patients, and 38% enrolled a significantly greater proportion of males than the US rectal cancer population. These demographic differences were more prominent among CRT trials than surgical trials. Half of all trials enrolled patients who were on average more than 7 years younger and enrolled a 5% greater proportion of males than their respective continental rectal cancer populations. Patients enrolled in trials had more advanced cancers than their corresponding continental populations. Sociodemographic data was rarely reported.

Patients enrolled in trials were younger, predominantly male, and had advanced stage cancer when compared to the rectal cancer population. Sociodemographic variables are underreported, further limiting equal participation in clinical trials. Future rectal cancer RCTs should strive to recruit representative samples. To enhance recruitment of women and underrepresented minorities, tailored recruitment strategies must be implemented.