Possible aetiological factors in leukaemias in Africa

Cancer of childhood in sub-Saharan Africa

Measurement of incidence rates of childhood cancer in Africa is difficult. The study 'Cancer of Childhood in sub Saharan Africa' brings together results from 16 population-based registries which, as members of the African Cancer Registry Network (AFCRN), have been evaluated as achieving adequate coverage of their target population. The cancers are classified according to the third revision of the International Classification of Childhood Cancer (ICCC-3) and recorded rates in Africa are compared with those in childhood populations in the UK, France, and the USA. It is clear that, in many centres, lack of adequate diagnostic and treatment facilities leads to under-diagnosis (and enumeration) of leukaemias and brain cancers. However, for several childhood cancers, incidence rates in Africa are higher than those in high-income countries. This applies to infection-related cancers such as Kaposi sarcoma, Burkitt lymphoma, Hodgkin lymphoma and hepatocellular carcinoma, and also to two common embryonal cancers - retinoblastoma and nephroblastoma. These (and other) observations are unlikely to be artefact, and are of considerable interest when considering possible aetiological factors, including ethnic differences in risk (and hence genetic/familial antecedents). The data reported are the most extensive so far available on the incidence of cancer in sub Saharan Africa, and clearly indicate the need for more resources to be devoted to cancer registration, especially in the childhood age range, as part of an overall programme to improve the availability of diagnosis and treatment of this group of cancers, many of which have-potentially-an excellent prognosis.

Mutation rate estimation for 15 autosomal STR loci in a large population from Mainland China

STR, short tandem repeats, are well known as a type of powerful genetic marker and widely used in studying human population genetics. Compared with the conventional genetic markers, the mutation rate of STR is higher. Additionally, the mutations of STR loci do not lead to genetic inconsistencies between the genotypes of parents and children; therefore, the analysis of STR mutation is more suited to assess the population mutation. In this study, we focused on 15 autosomal STR loci. DNA samples from a total of 42,416 unrelated healthy individuals (19,037 trios) from the population of Mainland China collected between Jan 2012 and May 2014 were successfully investigated. In our study, the allele frequencies, paternal mutation rates, maternal mutation rates and average mutation rates were detected. Furthermore, we also investigated the relationship between paternal ages, maternal ages, area, the time of pregnancy and average mutation rate. We found that the paternal mutation rate was higher than the maternal mutation rate and the paternal, maternal, and average mutation rates had a positive correlation with paternal age, maternal age and the time of pregnancy respectively. Additionally, the average mutation rate of coastal areas was higher than that of inland areas.

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15 autosomal STR loci were analyzed in a large scale population in Mainland China.

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With increases of repeat units the event of loss is more than that of gain.

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The paternal mutation rate is higher than the maternal mutation rate.

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There is a positive correlation between mutation rates and age and pregnancy time.

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The average mutation rates of coastal areas are higher than that of inland areas.

Descriptive epidemiology of de novo acute leukaemia in the Sultanate of Oman

A hospital-based epidemiological study of de novo acute leukaemia was carried out in the Sultanate of Oman, a sparsely populated Arabian Gulf country which has undergone rapid and dramatic socio-economic changes recently. A total of 65/99 Omanis (66%) were diagnosed as acute lymphoblastic leukaemia (ALL) and 34/99 (34%) as acute myeloid leukaemia (AML). Trends and peak values in age-specific incidence rates for ALL are generally in line with those of Western countries. The proportion of T-ALL cases is however higher than that in Caucasian populations but lower than in many non-white populations. AML frequency particularly in childhood is similar to that observed in many African countries.

Childhood leukaemias in New Zealand: time trends and ethnic differences

Registrations from the New Zealand Cancer Registry were used to examine time trends in the incidence of leukaemias among children aged 0-14. There was a statistically significant increase in the incidence of leukaemia among children aged 0-4 during 1953-57 to 1988-90. In this age group, the recorded incidence rate increased from 4.89 per 100,000 person-years in 1953-57 to 7.92 in 1988-90. During 1973-77 to 1988-90 (and probably in earlier years), the increase was due to an increase in acute lymphoblastic leukaemia (ALL). The trends were unlikely to be due to changes in diagnosis or case ascertainment. The childhood leukaemia trends might be related to trends in family size, maternal age, socioeconomic level or exposure to infections. However, there are uncertainties about the importance of these factors or about their trends. The incidence of acute non-lymphoblastic leukaemia (ANLL) decreased between 1968-72 and 1988-90. The time trends highlight the likely importance of environmental factors in the aetiology of childhood leukaemias in New Zealand. The risk of ALL was lower in the Maori than in the non-Maori population (relative risk Maori/non-Maori 0.74). The risk of ANLL was higher among Maori (relative risk 1.84).

The epidemiology of leukemia in Kuwait

This study reports the occurrence of leukemia subtypes in Kuwait between 1979 and 1989. The cases were analyzed by age, sex, Kuwaiti and non-Kuwaiti nationality status. Of the total 723 cases, acute lymphoblastic leukemia (ALL) was the most frequent (44.2%), exhibited a peak incidence in the 0-4 years age group and was also the most common leukemia of childhood (90.5%). Acute myeloblastic leukemia (AML) constituted 32.4% of leukemia and showed a progressive increase in incidence with age. Chronic myeloid leukemia (CML) constituted 14.8% and chronic lymphocytic leukemia (CLL) 8.6% of all cases. The incidence, age and sex distribution of ALL, AML and CML was similar to that in the developed Western countries while the lesser frequency of CLL was similar to that in the Orient. This pattern of leukemia subtypes may be related to the population structure consisting of the predominantly young in Kuwait, and the peak incidence of ALL in the very young to the socio-economic conditions.

T-lymphocyte sub-populations in orbito-ocular granulocytic sarcoma (OOGS) and acute myelocytic leukemia (AML): a preliminary study

The aetiology of GS remains obscure and a little is known about the immune competence of these patients. Interestingly, all children with OOGS were from low 'socio-economic status' and showed diminished delayed hypersensitivity reactions and reduced T cell counts (E-R) in our previous observation. We present herewith a preliminary data on evaluation of T cell sub-populations determined by monoclonal antibodies (CD3, CD4, CD8 and CD16 cells) in 10 patients with OOGS and AML prior to treatment. Quantitative immunoglobulin determinations of IgA, IgM, IgG were also made. The percentage of Pan T (CD3), CD4, CD8 cells were significantly lower than those in the controls (p < 0.01). The immunoglobulin levels were slightly elevated suggesting normal B cell functions. In conclusion, these preliminary findings suggest that cellular immune deficiency may be an underlying cause.

Epidemiology of acute leukaemia in the Cape Province of South Africa

Of 535 consecutive cases of acute leukaemia diagnosed in the Cape Province between 1978 and 1985, demographic data are incomplete in 75 black patients and they have had to be excluded from the spatial analysis. Of the remaining 460 cases, 223 (48.5%) occurred in white patients and 237 (51.5%) in those of mixed ancestry, classified as coloureds according to the Population Registration Act No. 30 of 1950. The average incidence was 2.12, 1.37 and 0.58/100,000 for whites, coloureds and blacks respectively. There was no temporal trend in the incidence of acute leukaemia between the three race groups. The median age for whites was 30 years and for the coloureds was 15 years, which is comparable to the 16 years for the black patients. The two-peak age distribution for leukaemia was seen in the white group, but was absent in the other two groups. This is accounted for by a different distribution in non-lymphoblastic as opposed to lymphoblastic subtypes. Furthermore, there was a disproportionately high frequency of acute progranulocytic leukaemia in the black patients, whereas the white and coloured groups were similar. There was a single, clearly defined macro-scale cluster restricted to white patients in Statistical Region 17 (SR-17). This exploratory study provides the first epidemiologic data for acute leukaemia in the Cape Province. It needs to be extended in order to verify these observations under more controlled circumstances and to seek evidence for some environmental factors that may account for the geographical cluster.