When it comes to surviving childhood acute lymphoblastic leukemia (ALL), improving treatment results may come down to one simple rule for patients: Take your medicine.

Although researchers have greatly improved the outlook for childhood ALL, children of some races or ethnic groups still do better with the cancer than others. Now City of Hope scientists have found a likely reason — Latino children are more likely to miss doses of medicine than are non-Latino white children.

Smita Bhatia (Photo by Walter Urie Photography)

Smita Bhatia, M.D., M.P.H., the Ruth Zeigler Chair in Population Sciences, led a team that examined more than 8,000 cases of ALL in which children received the same therapy — called mercaptopurine, or 6-MP — but had different outcomes across various ethnicities.

“Children are required to take an oral medication at home for two years as part of ALL treatment,” said Bhatia, who directs City of Hope’s Center for Cancer Survivorship. Her team thought it possible that simply missing doses of oral chemotherapy could increase the likelihood of a relapse. And if so, social factors might explain the ethnic differences in outcomes.

The research team focused on 332 Latino and non-Latino white patients under age 21 who were diagnosed with ALL. The patients received special prescription bottles with microchips in their caps that tracked dates and times the bottles were opened. Also, patients were monitored monthly to measure levels of chemotherapy in their blood.

About 86 percent of the Latino patients kept to the treatment plan over the six-month course of the study. That was much less than the 93 percent of non-Hispanic white patients who stuck to the treatment plan.

And six years later, 81 percent of Latino children had no sign of the disease while 94 percent of non-Latino white children were disease-free.

After studying the data, Bhatia’s team found a clear correlation: Ethnic differences in survival were linked to whether patients stayed on their oral 6-MP regimen and to patients’ sociodemographic status.

The findings stress the importance of developing culturally appropriate tools to help patients stick to their therapies.

“We found that most patients who missed doses said they simply forgot to take them or something interrupted their daily routine and only 5 percent skipped doses because of side effects,” said Bhatia. “We believe that in addition to developing better treatments, we should focus on how to improve adherence to current oral chemotherapy by using a systematic, comprehensive approach that is informed by the results of this study.”

Bhatia also is examining adherence in African-American patients, who have the lowest survival outcomes among children with leukemia, to find if similar factors are at play.