Maternal birthplace may affect offspring cancer risk

The children of Hispanic mothers born outside the United States appeared to have reduced risk for several cancers, including glioma, astrocytoma, neuroblastoma and Wilms’ tumor, according to results of a population-based case–control study.

Researchers sought to investigate whether the Hispanic epidemiologic paradox — a phenomenon wherein Hispanic women who were not born in the United States experience better pregnancy outcomes than their U.S.–born counterparts — extends to childhood cancer risks.

“This advantage is observed in immigrants despite high levels of poverty, lower maternal educational attainment and late entry into prenatal care services,” Julia E. Heck, PhD, associate professor of research at the UCLA Fielding School of Public Health, and colleagues wrote. “... Our study suggests that the children of non-U.S.–born Hispanic mothers retain, at least in part, the cancer risk observed in their countries of origin.”

Heck and colleagues evaluated data from California birth records of children born between 1983 and 2011.

The study consisted of 13,666 children who were diagnosed with cancer before the age of 6 years and 15.5 million children without cancer who served as controls.

Researchers classified the children as being born to non-Hispanic white mothers (n = 4,246,295; 51.3% male), U.S.–born Hispanic mothers (n = 2,548,822; 51% male) or non-U.S.–born Hispanic mothers (n = 4,397,703; 51% male).

Data showed that compared with children born to non-Hispanic white U.S.–born mothers, children of non-U.S.–born Hispanic mothers had a statistically significant decreased risk for glioma (HR = 0.5, 95% CI, 0.44-0.58), astrocytoma (HR = 0.43, 95% CI, 0.36-0.51), neuroblastoma (HR = 0.47, 95% CI, 0.4-0.54) and Wilms’ tumor (HR = 0.7, 95% CI, 0.59-0.82).

Risk estimates for children born to U.S.–born Hispanic mothers fell between the risk for children of white U.S.–born and Hispanic non-U.S.–born mothers for glioma (HR = 0.71, 95% CI, 0.61-0.83), astrocytoma (HR = 0.62, 95% CI, 0.51-0.75), neuroblastoma (HR = 0.66, 95% CI, 0.56-0.78) and Wilms’ tumor (HR = 0.88, 95% CI, 0.73-1.06).

However, Hispanic children appeared at risk for acute lymphoblastic leukemia (HR for children of U.S.–born Hispanic mothers = 1.2; 95% CI, 1.1-1.32; HR for children of non-U.S.–born Hispanic mothers = 1.06; 95% CI, 0.98-1.15) and Hodgkin lymphoma (HR for children of U.S.–born Hispanic mothers = 2.49; 95% CI, 1.21-5.13; HR for children of non-U.S.–born Hispanic mothers = 2.35; 95% CI, 1.24-4.47).

“We ... observed excesses of Hodgkin lymphoma among Hispanic children, which may be attributable in part to higher infection rates with Epstein-Barr virus,” the researchers wrote. “Epstein-Barr virus-positive Hodgkin lymphoma is more common among Hispanic individuals and is associated with mixed-cellularity subtype.”

Notably, the risk for bone tumor cancers appeared elevated among the children of U.S.–born Hispanic mothers compared with the children of non-U.S.–born Hispanic mothers (HR = 1.38, 95% CI, 0.83-2.31vs. HR = .05; 95% CI, 0.29-0.87).

“The elevated risk for bone tumors among the children of U.S.–born Hispanic mothers, in comparison with the lower risk among the children of non-U.S.–born Hispanic mothers, was notable given what is known about the differences in height between Mexican and Mexican American individuals,” the researchers wrote. “Height is a risk factor for several adult cancers and has been implicated in some studies of osteosarcoma and Ewing sarcoma.”

Heck and colleagues then stratified data for those with cancer by Mexican (n = 3,201) and Mexican American (n = 1,948) ancestry compared with other Hispanic ethnicities because 80% of Hispanic Californian mothers identified has having Mexican ancestry.

Children of Mexican-born mothers had a higher risk for yolk sac tumors (HR = 1.46, 95% CI, 0.99-2.17), but greater risk reductions for non-Hodgkin lymphoma (HR = 0.59; 95% CI, 0.37-0.92), ependymomas (HR = 0.69; 95% CI, 0.49-0.97) and Wilms’ tumor (HR = 0.69; 95% CI, 0.58-0.82).

Heck and colleagues acknowledged a lack of information on the duration of a mother's residence in the United States and the lack of means to measure acculturation serve as study limitations.

“Incorporating the immigrant experience into studies of childhood cancer may help to inform research on disease etiology, identify vulnerable populations, and highlight opportunities for cancer prevention,” the researchers wrote. “Further studies should explore the differences in risk incurred by variation in environmental, behavioral and infectious exposures between non-U.S.– and U.S.–born Hispanic mothers.”– by Nick Andrews

Disclosure : Heck and colleagues report no relevant financial disclosures.