Cancer in the European population of Harare, Zimbabwe, 1990-1992

Black-white differences in cancer risk in Harare, Zimbabwe, during 1991-2010

Data from 20 years of cancer registration in Harare (Zimbabwe) are used to investigate the risk of cancer in the white population of the city (of European origin), relative to that in blacks (of African origin). In the absence of information on the respective populations-at-risk, we calculated odds of each major cancer among all cancers, and took the odds ratios of whites to blacks. Some major differences reflect obvious phenotypic differences (the very high incidence of skin cancer-melanoma and nonmelanoma--in the white population), whereas others (high rates of liver cancer, Kaposi sarcoma and conjunctival cancers in blacks) are the result of differences in exposure to infectious agents. Of particular interest are cancers related to lifestyle factors, and how the differences in risk are changing over time, as a result of evolving lifestyles. Thus, the high risk of cancers of the esophagus and cervix uteri in blacks (relative to whites) and colorectal cancers in whites show little change over time. Conversely, the odds of breast cancer, on average four times higher in whites than blacks, has shown a significant decrease in the differential over time. Cancer of the prostate, with the odds initially (1991-1997) 15% higher in whites had become 33% higher in blacks by 2004-2010.

20-years of population-based cancer registration in hepatitis B and liver cancer prevention in the Gambia, West Africa

BACKGROUND

The Gambia Hepatitis Intervention Study (GHIS) was designed as a randomised control trial of infant hepatitis B vaccination applied to public health policy, with the main goal of preventing primary liver cancer later in adult life in The Gambia. To that effect, the National Cancer Registry of The Gambia (NCR), a population-based cancer registry (PBCR), was established in 1986 to actively collect data on all cancer diagnosis nation-wide. We extracted 20-years (1990-2009) of data to assess for the first time, the evolution of the most common cancers, also describe and demonstrate the role of the PBCR in a hepatitis B and liver cancer prevention programme in this population.

METHODS AND FINDINGS

We estimated Age-Standardised Incidence Rates (ASR (W)) of the most common cancers registered during the period by gender. The registration period was divided into four 5-year intervals and incidence rates were estimated for each interval. The most common cancers in males were liver, prostate, lung plus bronchus, non-Hodgkin lymphoma (NHL) and stomach, accounting for 60%, 5%, 4%, 5% and 3%, respectively. Similarly, cancers of the cervix uteri, liver, breast and NHL, were the most common in females, accounting for 33%, 24%, 11% and 4% of the female cancers, respectively.

CONCLUSIONS

Cancer incidence has remained relatively stable over time, but as shown elsewhere in sub-Saharan Africa the disease is a threat in The Gambia. The infection related cancers which are mostly preventable (HBV in men and HPV/HIV in women) were the most common. At the moment the data is not enough to detect an effect of hepatitis B vaccination on liver cancer incidence in The Gambia. However, we observed that monitoring case occurrence through PBCR is a key public health pre-requisite for rational planning and implementation of targeted interventions for improving the health of the population.

Dangerous liaisons: molecular basis for a syndemic relationship between Kaposi's sarcoma and P. falciparum malaria

The most severe manifestations of malaria (caused by Plasmodium falciparum) occur as a direct result of parasitemia following invasion of erythrocytes by post-liver blood-stage merozoites, and during subsequent cyto-adherence of infected erythrocytes to the vascular endothelium. However, the disproportionate epidemiologic clustering of severe malaria with aggressive forms of endemic diseases such as Kaposi's sarcoma (KS), a neoplasm that is etiologically linked to infection with KS-associated herpesvirus (KSHV), underscores the significance of previously unexplored co-pathogenetic interactions that have the potential to modify the overall disease burden in co-infected individuals. Based on recent studies of the mechanisms that P. falciparum and KSHV have evolved to interact with their mutual human host, several new perspectives are emerging that highlight a surprising convergence of biological themes potentially underlying their associated co-morbidities. Against this background, ongoing studies are rapidly constructing a fascinating new paradigm in which the major host receptors that control parasite invasion (Basigin/CD147) and cyto-adherence (CD36) are, surprisingly, also important targets for exploitation by KSHV. In this article, we consider the major pathobiological implications of the co-option of Basigin/CD147 and CD36 signaling pathways by both P. falciparum and KSHV, not only as essential host factors for parasite persistence but also as important mediators of the pro-angiogenic phenotype within the virus-infected endothelial microenvironment. Consequently, the triangulation of interactions between P. falciparum, KSHV, and their mutual human host articulates a syndemic relationship that points to a conceptual framework for prevalence of aggressive forms of KS in malaria-endemic areas, with implications for the possibility of dual-use therapies against these debilitating infections in resource-limited parts of the world.

Trends in the incidence of cancer in the black population of Harare, Zimbabwe 1991-2010

Incidence rates of different cancers have been calculated for the black population of Harare, Zimbabwe for a 20-year period (1991-2010) coinciding with continuing social and lifestyle changes, and the peak, and subsequent wane, of the HIV-AIDS epidemic. The overall risk of cancer increased during the period in both sexes, with rates of cervix and prostate cancers showing particularly dramatic increases (3.3% and 6.4% annually, respectively). By 2004, prostate cancer had become the most common cancer of men. The incidence of cancer of the esophagus, formerly the most common cancer of men, has remained relatively constant, whereas rates of breast and cervix cancers, the most common malignancies of women, have shown significant increases (4.9% and 3.3% annually, respectively). The incidence of Kaposi sarcoma increased to a maximum around 1998-2000 and then declined in all age groups, and in both sexes The incidence of squamous cell cancers of the conjunctiva is relatively high, with temporal trends similar to those of Kaposi sarcoma. Non-Hodgkin lymphoma, the fifth most common cancer of men and fourth of women, showed a steady increase in incidence throughout the period (6.7-6.9% annually), although rates in young adults (15-39) have decreased since 2001. Cancer control in Zimbabwe, as elsewhere in sub-Saharan Africa, involves meeting the challenge of emerging cancers associated with westernization of lifestyles (large bowel, breast and prostate), while the incidence of cancers associated with poverty and infection (liver, cervix and esophagus) shows little decline, and the residual burden of the AIDS-associated cancers remains significant.

Breast Cancer among Immigrants: A Systematic Review and New Research Directions

This paper highlights the relationship between migration and female breast cancer. A comprehensive review aimed at identifying risk and protective factors that cut across races and ethnicities was performed. A total of 79 studies (1971-2005) from 16 countries were reviewed. The findings are consistent with existing knowledge about the importance of potentially modifiable environmental and behavioral determinants of risk, acting both pre- and post-migration. While the acculturation-based risk transition model is strong, it is not always supported. As a new direction for migrant studies, we extrapolate the review findings to the experience of Eastern European (EE) immigrants. Health data on this population, typically characterized by low health motivation and passive receipt of preventive efforts, are largely unavailable. Based on relevant theory, empirical and qualitative studies, two breast cancer prevention models for the EE immigrant population are proposed and the need for future research using ethnically disaggregated data is discussed.

Iron overload in Sub-Saharan Africa: to what extent is it a public health problem?

Excessive deposition of Fe in the organs and tissues of Sub-Saharan Africans was first described in South Africa in 1929. Fe overload, or siderosis, was initially attributed to infections and to metallic poisoning (Cu, Sn, Zn), and then to malnutrition. In 1953 it was hypothesized that it was due primarily to excessive Fe intake derived from foods and drinks prepared in Fe vessels. Recently, in 1992 it was advanced that a gene distinct from any HLA-linked locus may also play a role. As to sequelae, in early research on series of hospital patients, the condition was linked to scurvy, osteoporosis, diabetes, cirrhosis, and latterly, to hepatocellular cancer and tuberculosis. Accordingly, many have concluded that Fe overload is responsible for considerable morbidity and mortality, that adventitious Fe intake should be reduced, and that phlebotomy be recommended for those severely affected. However, there are numerous limitations in the evidence. There are also problems in interpretation, since levels of Fe in the serum are affected additionally by a variety of factors: infection, inflammation, certain cancers and alcohol intake. These considerations complicate attempts to assess to what extent the associations described denote causation, and whether Fe overload has significant ramifications for ill in the general African population. While the adverse sequelae of overload may be less of significance than many believe, the precise pathogenicity of the phenomenon will remain uncertain until further investigations, including prospective studies, are undertaken.

Cancer survival in a southern African urban population

This paper provides the first comprehensive population based cancer survival estimates from the African continent. Five-year absolute and relative survival estimates are presented for black and white Zimbabwean patients diagnosed with cancer in Harare, Zimbabwe between the years 1993 and 1997. The survival of black Zimbabwean cancer patients are among the lowest ever reported from population based cancer registries. For most cancer sites, white Zimbabwean patients have much higher survival than black Zimbabweans, except for lung and colorectal cancer, for which the estimates are similarly poor. Race specific comparisons to cancer patients in the United States show that Zimbabwean patients have much lower survival than American cancer patients and that the gap between black Zimbabwean patients and black American patients is broader than between white Zimbabwean and white American patients. Access to and the ability to pay for medical care may be a very important barrier to better survival for the majority of black Zimbabwean patients and the most important cause for the very low cancer survival in this population.