The addition of biologic agents to cytotoxic chemotherapy significantly improved overall survival (OS) in metastatic colorectal cancer (mCRC) compared with chemotherapy alone, and the additional benefit was as apparent in Black patients as in whites, a comparative effectiveness analysis of Medicare data showed.
In the overall cohort of 5,617 patients, the median OS was 17.9 months (95% CI 17.3-18.7) in those who received biochemotherapy compared with 8.3 months (95% CI 9.1-9.9) in patients who received chemotherapy alone (P<0.001), reported Sanjay Goel, MD, MS, of Albert Einstein College of Medicine and Montefiore Medical Center in New York City, and colleagues.
In 4,542 patients with known race and ethnicity, the added benefit of biologic agents, usually given within 3 months of chemotherapy, led to a 41% improvement in OS compared with chemotherapy alone (HR 0.59, 95% CI 0.55-0.64, P<0.001), the team said in the study in JAMA Network Open.
Moreover, the additional use of biologic agents improved OS equally by race, at 17.8 months versus 9 months for chemotherapy alone among white patients compared with 18.6 versus 9.9 months, respectively, in black patients (P<0.001 for both endpoints), the investigators noted.
"We report for the first time to date that Black patients experience a survival advantage (with a 42% improvement in survival) from the addition of biologic agents to cytotoxic chemotherapy similar to the survival benefit found for white patients," the researchers wrote.
Still, caution is warranted, they explained: "Such large database analysis is not a substitute for the low representation of racial and ethnic minority groups in RCTs [randomized clinical trials]. Until racial and ethnic minority groups are equitably included in RCTs, oncologists may prescribe biologic agents for patients with mCRC with reasonable faith in their early benefit, regardless of race."
The population-based, retrospective cohort study included 5,617 patients diagnosed with mCRC from 2004 to 2011 using the NCI Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database.
Among those, 70.7% received a biologic agent. Biological therapy was initiated within 3 months of chemotherapy in about 73% of patients. Median age of the patients was 72 (interquartile range 68-78), approximately half were women, and the colon was the primary site in 76%.
About 12% of the patients were Black; 88% were white; and there were no differences in the receipt of one, two, or more lines of chemotherapy or in the receipt of biologic agents, or in the rates at which Black and white patients received biologic agents.
"This finding may suggest that given the appropriate medical intervention unencumbered by access to care or medication coverage, Black patients can experience the same clinical benefit as white patients: Thus, the driving force behind the lower OS among Black patients may be the lack of adequate access to high-quality health care," Goel and co-authors wrote.
Limitations to the study, the team said, included that the SEER-Medicare linked database lacks information on tumor mutational status as well as that the SEER Medicare population is better insured, more affluent, and more urban than the rest of the country.