Cancer incidence differs between African- and U.S.-born blacks

Last Updated: 2017-04-17

By Marilynn Larkin

NEW YORK (Reuters Health) - The incidence of various types of cancers differs significantly between blacks born in the United States and Sub-Saharan African-born blacks living in the U.S., researchers say.

Sub-Saharan African-born blacks are among the fastest growing populations in the U.S., but data on cancer incidence in this group is lacking, according to Dr. Stacey Fedewa, Director of Screening and Risk Factor Surveillance at the American Cancer Society and colleagues.

Using registry data for 2000 through 2012 from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute, the team calculated age-standardized proportional incidence ratios (PIRs) for the top 15 cancers in African-born blacks and compared the frequency with that in U.S.-born non-Hispanic blacks.

The African-born blacks were younger at the time of diagnosis (median age, 55 versus 64 in the U.S.-born group); more likely to be married (56% versus 36%) and uninsured (for those under age 65, 15% versus 9%; for those 65 and older, 18% versus 1%).

African-born blacks were more likely to live in more affluent counties compared with U.S.-born blacks (60% versus 33%), the authors reported in Cancer, online April 13.

Overall, African-born blacks had significantly higher PIRs of infection-related cancers, including liver (2.15 for men, 2.76 for women), stomach (1.14 for men, 1.54 for women) and Kaposi sarcoma (1.23 for men, 12.06 for women); blood cancers such as leukemia (1.40 for men, 1.62 for women) and non-Hodgkin lymphoma (1.34 for men, 1.19 for women); prostate cancer (1.53); and among women, thyroid cancers (2.05).

By contrast, African-born blacks had lower PIRs for lung (0.30) and colorectal (0.81) cancers.

Cancer incidence in African-born versus U.S.-born blacks also varied by region of birth. For example, the significantly higher PIRs for liver cancer and non-Hodgkin�€™s lymphoma noted among African-born men and for thyroid cancer in African-born women were limited to Eastern African-born blacks. The higher PIR for prostate cancer was seen in Western African-born blacks.

Dr. Fedewa told Reuters Health by email, �€œThere are several differences in lifestyle and other factors that may account for our findings. For example, we observed a lower proportion of smoking-related cancers among African-born blacks compared U.S.-born blacks, and this may reflect lower smoking prevalence in this group.�€

�€œWe also observed a lower proportion of colorectal cancers in African-born blacks compared to US born blacks, and differences in dietary patterns may contribute to this finding,�€ she said.

Dr. Paolo Boffetta, Associate Director for Cancer Prevention, Tisch Cancer Institute at Mount Sinai in New York City, told Reuters Health by email, �€œThis detailed analysis of cancer among Sub-Saharan African immigrants confirms the notion that cancer in first-generation immigrants largely reflects the pattern of the region of origin (e.g., high risk of infection-related cancers), but also suggests that for several cancers (e.g., lung, colorectal cancer) the high risk in African-Americans is largely due to behavioral, environmental and societal factors, in addition to genetic factors (e.g., prostate cancer).�€

Dr. Boffetta, who was not involved in the research, added �€œThis study also demonstrates the importance of population-based cancer registries, and in particular the SEER Program, to understand major patterns and trends in cancer risk, which would inform clinical and public health decisions.�€

SOURCE: http://bit.ly/2oOZ1a3

Cancer 2017.