Cancer risks in blacks: 'a complex, entangled web'

Cancer is the second leading cause of death among blacks in the United States. Previous studies seeking to understand the phenomenon have historically grouped all blacks living here under a single umbrella.

New research from UNLV's School of Community Health Sciences shows that, when compared to other major racial-ethnic groups (whites, Asians, Hispanics, American Indians, etc.), U.S.-born blacks have the highest cancer mortality rates while black Caribbean immigrants in the U.S. have the lowest. The study also found differences within the Caribbean immigrant population when comparing, for example, the types of cancer among those born in Haiti and Jamaica to the other roughly 20 countries/territories in that region, or to blacks still living in their countries of origin.

Scientists combed through more than 185,000 death certificates -- 20,000 of them belonging to blacks -- recorded between 2008 and 2012 by the Florida Department of Health Vital Statistics. They identified the types of cancer responsible for deaths among U.S.- and foreign-born black populations and compared their mortality rates with whites and Caribbean Hispanics. Researchers chose Florida because of its sizable portion of U.S.-born black and black immigrant populations.

Among the findings published this fall in in Cancer Control, the scientific journal of the Moffitt Cancer Center:

*For all cancers combined, mortality risk was much higher (at least twice in males and 60 percent in females) for U.S.-born blacks than black Caribbeans living in the U.S.

*The biggest intraracial difference was observed for lung cancer, for which U.S.-born blacks had nearly four times greater risk of death than Caribbean immigrants. It was the leading cause of cancer mortality among U.S.-born black men versus prostate cancer for Caribbean men. Still, U.S.-born blacks, rather than Caribbean-born men, tend to have the highest incidence of "aggressive" prostate cancer in the world.

*The leading causes of cancer death among U.S.-born black women were lung and breast cancers. For Caribbean-born black women, breast cancer was also the leading cancer mortality cause, though the risk is 1.7 times lower than for U.S.-born women -- numbers that surprised researchers since previous studies have documented lower rates of mammography among blacks born outside the U.S.

*The mortality rates of Haitians and Jamaicans living in Florida were lower than those in their countries of origin, especially when it comes to cervix, stomach, and prostate cancers.

Researchers say the findings turn on its head the long-held belief that disparities in cancer outcomes for blacks in the U.S., including immigrants less likely to have consistent health insurance, are linked to socioeconomic status and lack of access to quality health care.

The results point to a much more complex scenario: Haitian and Jamaican populations in Florida, who are likely to be at least as economically disadvantaged as U.S.-born blacks, have lower cancer mortality rates than even whites and Hispanics. Thus, more research is needed to clarify and address the reasons for such poor cancer mortality in U.S.-born Blacks.

"Blacks are not all the same with regard to their cancer experience," said Dr. Paulo S. Pinheiro, a UNLV associate professor of epidemiology and biostatistics, who led the National Institutes of Health-funded team of international researchers. "Blacks, or individuals of African descent, in the U.S. are very heterogeneous, with diverse social, cultural, and economic backgrounds that fundamentally impact health."

So far, researchers say, it appears cancer disparities by race are the result of a "complex, entangled web of differences in risk" stemming from social and cultural factors -- such as smoking and dietary habits, types of family structure and social support, expectations regarding medical care, and cumulative lifetime exposure to cancer risk factors, which directly impact cancer incidence, access to and availability of early detection, and timely treatment.

For example, lower lung cancer death rates among Caribbean-born blacks may be partially explained by other studies showing blacks born outside the U.S. are less likely to smoke. Caribbean immigrants tend to maintain their traditional diets containing less red meat and higher intake of whole grains, fruits, and vegetables, which protect against colorectal cancer. Immigrant fertility rates and breastfeeding patterns may help explain breast cancer differences.

Still, several patterns appeared to rely on race or genetics alone: all black populations analyzed in the study had in common higher death rates for endometrial (uterine), premenopausal breast, and prostate cancers than whites and Hispanics.

Pinheiro said continued research is important to learn what predisposes different groups to certain types of cancer and for improving cancer outcomes for all populations, especially as America's foreign-born black population increases.

Jamaicans and Haitians in Florida likely benefitted from better access to cancer screening and treatment, which resulted in lower cervical and prostate cancer mortality trends detected in the study, said Pinheiro. On the negative side, Haitians seemed to acquire higher risk for obesity-related cancers such as colorectal and endometrial cancers after moving to the United States. Health programs in these communities should emphasize preserving positive health aspects of their cultures and resisting the adoption of unfavorable lifestyle habits that are more common in the U.S., such as unhealthy diets, sedentary lifestyles, smoking, and excessive alcohol use, he said.

"Targeted interventions for cancer prevention and control should take into account the specificity of each black subgroup: U.S. blacks, Haitians, and Jamaicans," urged Pinheiro.

See the full study at: https://moffitt.org/media/5773/3-347-pinheiro.pdf