Burden of Cancers Attributable to Infectious Agents in Nigeria: 2012-2014.
BACKGROUND
Infections by certain viruses, bacteria, and parasites have been identified as risk factors for some cancers. In Nigeria, like many other developing countries, infections remain a leading cause of morbidity and mortality. While there are data on the incidence of different cancers in Nigeria, there has been no study of cancers attributable to infections. This study was carried out to determine the burden of cancers attributable to infections using data from two population-based cancer registries (PBCRs) in Nigeria.


METHODS
We obtained data on cancers associated with EBV, human papillomavirus (HPV), hepatitis B and C, HIV, HHV8,Helicobacter pylori, andSchistosomaspp. from the databases of Abuja and Enugu cancer registries in Nigeria. We used population-attributable fraction for infections-associated cancers in developing countries that are based on prevalence data and relative risk estimates from previous studies.


RESULTS
The PBCRs reported 4,336 incident cancer cases [age standardized incidence rate (ASR) 113.9 per 100,000] from 2012 to 2014, of which 1,627 (37.5%) were in males and 2,709 (62.5%) were in females. Some 1,030 (23.8%) of these cancers were associated with infections (ASR 44.4 per 100,000), while 951 (22.0%) were attributable to infections (ASR 41.6 per 100,000). Cancers of the cervix (n= 392, ASR 28.3 per 100,000) and liver (n= 145, ASR 3.4 per 100,000); and non-Hodgkin's lymphoma (n= 110, ASR 2.5 per 100,000) were the commonest infections-associated cancers overall. The commonest infectious agents associated with cancers in this population were HPV, EBV, hepatitis B and C, HIV, and HHV8.


CONCLUSIONS
Our results suggest that 23.8% of incident cancer cases in this population were associated with infections, while 22.0% were attributable to infections. The infections attributable cancers are potentially preventable with strategies, such as vaccination, risk factor modification, or anti-infective treatment.
Institute of Human Virology , Abuja , Nigeria.
Michael
M
Odutola
Department of Non-communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine , London , UK.
Elima E
EE
Jedy-Agba
Department of Public Health and Primary Care, Center for Cancer Genetic Epidemiology, University of Cambridge , Cambridge , UK.
Eileen O
EO
Dareng
Battelle Memorial Institute , Baltimore, MD , USA.
Emmanuel Aja
EA
Oga
National Hospital Abuja , Abuja , Nigeria.
Festus
F
Igbinoba
University of Abuja Teaching Hospital Gwagwalada , Gwagwalada , Nigeria.
Theresa
T
Otu
University of Nigeria Teaching Hospital Enugu , Enugu , Nigeria.
Emmanuel
E
Ezeome
Federal Ministry of Health , Abuja , Nigeria.
Ramatu
R
Hassan
Institute of Human Virology, Abuja, Nigeria; Department of Epidemiology and Public Health, Marlene and Stewart Greenebaum Comprehensive Cancer Center, Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, USA.
Clement A
CA
Adebamowo
Nigeria; cancer registry; cancers; infectious agents; population-attributable fraction