Puerto Ricans Have Lower Leukemia Risk, but Not in All Subtypes

A new analysis finds Puerto Ricans have lower rates of leukemia and leukemia-related mortality than other ethnic groups in the United States. However, study authors also found significant variance in the comparative risk levels when they stratified their data based on leukemia subtypes and age groups.

Findings were reported in PLOS One.

The study authors said previous research has already documented leukemia disparities among racial and ethnic groups in the United States. Yet, they said many of the existing studies have not included patients who are Puerto Rican.

“However, Hispanics in the United States represent a heterogeneous population, whereas the Puerto Rican population represents the second-largest Hispanic population in the nation,” the authors wrote.

In hopes of getting clearer insight into where the Puerto Rican population fits into the racial and ethnic disparities observed in leukemia, the investigators pulled data from the Puerto Rico Central Cancer Registry and the National Cancer Institute’s Surveillance, Epidemiology, and End Results database. They then compared leukemia data by incidence, mortality, and subtype, among racial and ethnic groups. The data covered 2015 to 2019.

The authors found non-Hispanic White individuals had a higher standardized incidence rate of leukemia (SIR, 1.47; 95% CI, 1.40-1.53) compared with Puerto Rican individuals, as well as a higher standardized mortality rate (SMR, 1.55; 95% CI, 1.45-1.65). Similarly, non-Hispanic Black individuals had a higher risk of leukemia and mortality from leukemia (SIR, 1.09; 95% CI, 1.04-1.15; SMR, 1.27; 95% CI, 1.19-1.35).

Conversely, non-Hispanic Asian/Pacific Islander individuals had a reduced risk (SIR, 0.78; 95% CI, 0.74-0.82; SMR, 0.83; 95% CI, 0.77-0.89), the authors found. Rates of leukemia and mortality were similar between the Puerto Rican population and the overall US Hispanic population, they found.

The investigators said the findings became more complex once they looked at leukemia subtypes. For instance, in acute lymphocytic leukemia (ALL), the Hispanic population had higher incidence and mortality rates vs non-Hispanic Black and White persons. Yet, children in Puerto Rico had lower incidence and mortality rates for ALL than the US Hispanic population cohort.

“Higher rates of ALL among US Hispanic children have been explained by genetic differences, environmental factors, and changes in diagnostics or lifestyle factors,” the authors said.

Puerto Ricans had a significantly lower risk of acute myeloid leukemia (AML) compared with the other racial and ethnic groups. Yet, that was not true among Puerto Rican persons aged 15 to 44, who had a higher risk of developing AML than the US Hispanic, non-Hispanic White, and non-Hispanic Asian/Pacific Islander cohorts, the authors said.

Chronic lymphocytic leukemia was more common in the non-Hispanic White cohort than other racial and ethnic groups, but those who were Puerto Rican had a higher risk of chronic myeloid leukemia (CML) than the non-Hispanic Asian/Pacific Islander or the US Hispanic groups. The authors cautioned, however, that there was a small number of CML cases in the data set.

The authors said there are a host of variables that could be at play, including cancer history, radiation exposure, and smoking.

“It is important to highlight that the differences observed in incidence and mortality of leukemia could be due to social and economic factors,” they added, noting that factors such as discrimination and limited access to care could be implicated in the disparities.

They said their data help explain disparity patterns related to the burden of leukemia.

“Therefore, our results support the need to develop prevention and control programs to reduce the incidence and mortality of leukemia, and as a consequence, increase the survival rates of leukemia,” they said.

Reference

Alvarado Ortiz M, Suárez Ramos T, Torres Cintrón CR, et al. Racial/ethnic disparities for leukemias in Puerto Rico and the United States of America, 2015-2019. PLoS One. Published online May 17, 2023. doi:10.1371/journal.pone.0285547