More than half of breast cancer patients are not well represented in conventional clinical trials, according to a study published in JCO Oncology Practice.
Study details and key findings
For the retrospective cohort study, researchers analyzed data from the national CancerLinQ Discovery database for women diagnosed with stage I-III breast cancer between 2005 and 2015.
Among the 11,770 patients included in the study, researchers found that 48% were well represented in conventional clinical trials, 45% were under-represented, and 7% were unrepresented.
In the study, patients with comorbidities or concurrent cancer were considered unrepresented in clinical trials. Non-white patients, as well as those under the age of 45 or 70 and older, were considered under-represented. Patients who were white, between 45 and 69 years old, and without comorbidities were considered well represented.
Overall, 71% of the study's patients were between 45 and 69 years old, 72% were white, and 51% were diagnosed with stage II breast cancer. In addition, just 6% had comorbidities, and only 2% had a concurrent cancer.
Among unrepresented patients, 76% were categorized as such due to comorbidities alone, 22% had concurrent cancer, and 2% had both.
In addition, 44% of under-represented patients were categorized as such based on age, 39% based race or ethnicity, and 17% on the basis of both age and race or ethnicity.
In their analysis, researchers used Cox proportional hazards models to evaluate five-year mortality by population group and patient characteristics, including age, comorbidity, and race. They adjusted for cancer stage, subtype, chemotherapy, and diagnosis year.
Notably, when compared with well represented patients, unrepresented patients faced almost three times the risk of five-year mortality.
Although there was no significant difference in the risk of five-year mortality between under-represented patients and well represented patients, under-represented patients who were under the age of 45 had a lower chance of five-year mortality and patients ages 70 and older had a higher chance of five-year mortality when compared with patients who were between 45 and 69 years old. (Gidwani et al., JCO Oncology Practice, 9/24/2021)