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Hispanics living in Texas had significantly worse survival for two types of leukemia, and those living at the U.S.-Mexico border had worse survival for multiple blood cancers, as compared with Hispanics in the rest of the state, cancer registry data showed.

Overall, the 10-year survival for acute lymphoblastic leukemia (ALL) was 28% for Hispanics younger than age 50 versus 39% for non-Hispanic whites in the same age range. For acute promyelocytic leukemia (APL), Hispanics younger than 50 had a 10-year survival of 69% compared with 76% for non-Hispanic whites.

An analysis of Hispanics living in the border city of El Paso showed significantly worse 10-year survival for ALL, acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and myelodysplastic syndrome (MDS), as compared with Hispanics in the rest of the state, as reported at the American Association for Cancer Research (AACR) virtual meeting. Non-Hispanic whites living in El Paso also had worse ALL survival as compared with the rest of the state.

"We observed that Hispanic ethnicity is associated with worse overall survival in patients with acute lymphoblastic leukemia and acute promyelocytic leukemia," said Alfonso Bencomo-Alvarez, PhD, of Texas Tech University Health Sciences Center El Paso. "Both Hispanic and non-Hispanic patients with acute lymphoblastic leukemia have worse outcomes in the border region, compared to the rest of Texas. However, with acute and chronic myeloid leukemia, Hispanic patients living near the border have a worse overall survival compared with the rest of Texas.

"It is important to highlight that El Paso, Texas, is located in health service region number 10, which is considered a medically underserved region with many financial and additional barriers to healthcare, mostly among the Hispanic population," he stated.

Possible Explanations, Implications

Ongoing studies aim to identify potential biological factors associated with the increased risk of hematologic malignancies in Hispanics, he added.

During a question-and-answer session that followed the presentation, Bencomo-Alvarez cited multiple factors that could have influenced the results. From a cultural perspective, Hispanics do not like going to see healthcare providers. A disproportionate number of Hispanics lack financial resources or health insurance. If they are undocumented, they fear that a trip to the doctor could lead to deportation.

"But definitely, as well, I think that there could be a biological component there, and we're trying to address that in our future studies," he said.

AACR Past President Elaine Mardis, PhD, of Nationwide Children's Hospital in Columbus, Ohio, added, "The genetic aspects are pretty mysterious at this time. We may not completely appreciate aspects of germline susceptibility in this setting, especially given the numbers and the comparison to non-Hispanic whites that were presented by Dr. Bencomo."

The study added to existing evidence of disparities in the epidemiology and outcomes of blood cancers among Hispanics. Previous studies showed that Hispanics have a higher incidence of pediatric leukemia and that diagnosis of ALL, AML, and APL occurs at a younger age in Hispanic adults, who also have worse prognosis.

The observational data have broad implications from a . Hispanics are the largest and fastest-growing minority group in the U.S., currently accounting for 18% (58 million) of the total population. Cancer is the leading cause of death among Hispanic-Americans, as compared with second-leading cause of death among non-Hispanic whites.

Blood cancer incidence and survival estimates had not been determined for an area with high Mexican-American population density, such as Texas.

"In contrast to the Hispanic population across the U.S., which is heterogeneous and includes Hispanics from various countries, the majority of Hispanics in Texas and at the border are Mexican," said Bencomo-Alvarez. "Therefore, studying Hispanics in this region gives us the opportunity to study a largely Mexican population as a way to better understand the disparities in this group."

Key Study Findings

The analysis involved data on blood cancers in the Texas Cancer Registry for the years 1995 to 2016. They identified 53,578 patients who had primary diagnoses of ALL, AML, APL, chronic lymphocytic leukemia (CLL), CML, MDS, or myeloproliferative neoplasm (MPN). The study population comprised 42,756 non-Hispanics and 10,822 Hispanics.

The most common diagnosis was CLL (n=18,296), followed by AML (12,807), MDS (10,875), CML (5,659, ALL (3,228), MPN (1,711), and APL (1,002). For all of the conditions, diagnosis occurred at a significantly younger age among Hispanics (P=0.0025 to P<0.0001). Age distribution for diagnosis of a blood cancer showed a significantly higher risk among Hispanics 40 or younger (P<0.00001).

Multivariate analyses showed that Hispanic ethnicity correlated with worse outcomes for ALL (HR 1.23, 95% CI 1.10-136, P<0.0001) and APL (HR 1.28, 95% CI 1.03-1.61, P=0.03). Survival analyses showed that Hispanics younger than 70 had worse survival for ALL, but particularly Hispanics younger than 50 (P<0.0001). Hispanics younger than 50 also had worse 10-year survival for APL (P=0.05).

The analysis of the impact of border residency included 10,822 patients (1,160 Hispanics) living in and around El Paso. Both Hispanics and non-Hispanic whites living at the border had worse 10-year survival for ALL as compared with the rest of Texas (P<0.0001). Hispanics at the border also had significantly worse 10-year survival for AML, CML, and AML versus Hispanics living elsewhere in the state (P<0.0001).

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