Racial Disparities Among Genes of Colon Cancer Patients

Depending on the patient’s race, the genes of colon cancer may differ, according to a study published in the Journal of the National Cancer Institute.

Researchers from the Mayo Clinic analyzed the genes of more than 3,300 stage III colon cancer patients in order to determine if racial disparities in colon cancer outcomes persist even after controlling for clinical and pathological variables. The patients were stratified into categories based on race: Asian, black, or white. The investigators examined the mutations of two key cancer related genes known as BRAF and KRAS — both of which have been linked to worse overall outcomes.

BRAF mutation frequency more often occurred in tumors of white patients (13.9 percent), more than twice the rate of tumors of Asians or blacks, the researchers discovered. KRAS mutations were the highest in black patients at 44 percent. For Asian patients, KRAS/ BRAF wild type mutations were the most common, at about 66 percent, the researchers found.

“These findings put the issue of race more prominently on the radar of investigators that cancer biology may contribute to race based disparities,” the study’s co lead author and Mayo Clinic oncologist Harry Yoon, MD, explained in a press release. “While it is too early to change the way we treat these patients, our results indicate that future studies are needed to examine potential biological drivers of these differences more closely.”

Colon cancers were most likely to recur in black patients, but only in patients younger than 50 years old. For Asian or white patients, the rate of recurrence within five years ranged between 22 and 35 percent, the researchers said.

Some of the reasons for the differences among races may be attributed to socioeconomic factors, like diagnoses at a later stage, or decreased access to healthcare and suboptimal treatment, the authors continued in the statement. However, all the patients in this particular study were treated and had their disease monitored through a clinical trial, so the researchers believe these are not adequate explanations.

“In addition to published data indicating that a limited number of genes are preferentially mutated in colon cancers from black versus white patients, our study revealed differences in the mutation frequencies of BRAF and KRAS oncogenes that provide prognostic information in colon cancer patients,” concluded the study’s other co lead author and Mayo Clinic oncologist Frank Sinicrope, MD. “Our data provide further evidence that colon cancers from blacks are intrinsically different and are associated with more aggressive clinical behavior in young black patients.”