Childhood Acute Lymphoblastic Leukemia: A Cluster in Southwestern Sardinia (Italy)

Epidemiology of acute lymphoblastic leukaemia in Sardinia, Italy: Age, sex, and environmental correlates

Using a database of 1974-2003 incident cases of haematological malignancies, we explored the time trend, geographic spread and socio-economic and environmental correlates of ALL incidence in Sardinia, Italy, by sex and age. The age- and sex-standardized (World population) ALL incidence rate was 2.0 per 100,000 (95% CI 1.8 - 2.1) and showed variable trend patterns by sex and age. In the total population, ALL incidence showed an annual per cent change of -1.4% (95% CI -0.59 - -3.34) over the study period, with a knot separating a downward slope in 1974-1996 from an increase in 1996-2003. ALL incidence replicated such pattern in women but not men, whose incidence did not substantially vary over the study period (APC = -2.57%, 95% CI -5.45 - 0.26). Among women, the spatial analysis suggested a clustering of ALL in the southwestern part of the region, whilst only a commune had a high posterior probability of a high ALL incidence among men. Three unrelated communes showed a high posterior probability of ALL at age ≤ 24; only the most populated urban centre showed excess cases at age ≥ 25 years. There was no correlation between the geographic spread of ALL at ages ≤ 24 and ≥ 25 years (p = 0.082). Urban residence was a risk factor for the younger age group. Residences near industrial settlements and in the most populated urban centre were risk factors for subjects aged ≥ 25 years. Our findings suggest age-related differences in ALL aetiology.

Haemolymphatic cancer among children in Sardinia, Italy: 1974-2003 incidence

OBJECTIVES

To explore the time trend and geographical distribution of childhood leukaemia incidence over the territory of the Italian region of Sardinia.

SETTING

All hospitals departments, diagnostic centres and social security agencies in Sardinia were regularly screened in 1974-2003 to identify, register and review the diagnoses of incident cases of haematological malignancies (HM).

PARTICIPANTS

The whole child population aged 0-14 resident in Sardinia.

PRIMARY AND SECONDARY OUTCOME MEASURES

Incidence and time trend of childhood HM and childhood acute lymphoblastic leukaemia (ALL) over the study period, and use of Bayesian methods to plot the probability of areas with excess incidence on the regional map.

RESULTS

Overall, 675 HM cases, including 378 ALL cases, occurred among children aged 0-14 years resident in Sardinia in 1974-2003, with an incidence rate of 6.97×10^-5 (95% CI 6.47 to 7.51) and 3.85×10^-5 (95% CI 3.48 to 4.26), respectively. Incidence of HM and ALL showed an upward trend along the study period especially among females. Three communes out of the 356 existing in 1974, namely Ittiri, Villa San Pietro and Carbonia, stand out as areas with excess incidence of HM and ALL in particular and another, Carloforte, for ALL only.

CONCLUSIONS

Our results might serve as convincing arguments for extending the coverage of routine cancer registration over the whole Sardinian population, while prompting further research on the genetic and environmental determinants in the areas at risk.

A case-only study of interactions between metabolic enzyme polymorphisms and industrial pollution in childhood acute leukemia

Cancer risk is modulated by gene-environment interactions between toxic exposure and genetic variation in carcinogen metabolism. Our objective was to assess interactions between exposure to industrial pollutants and polymorphisms affecting cytochrome P450s (CYP1A1 and CYP2E1) and glutathione S-transferases (GSTP1 and GSTT) in childhood acute leukemia (AL). A case-only design was conducted in 123 Chinese children with sporadic AL. Industrial plants in the vicinity were recorded and, if present, their size and proximity to the usual place of residence of AL children was evaluated. Unconditional logistic regression analysis was performed across the AL study group adjusting for age, gender, parental education, occupation and smoking, indoor and outdoor pesticide use, presence of television sets, refrigerators, microwave ovens and furniture material in children's rooms, and electric transformers, power lines, and telecommunication transmitters within 500 m. This analysis revealed an interaction between the GSTT null allele and industrial plants within 500 m of the residences of childhood AL patients (interaction odds ratio, COR=2.96, 95% CI: 1.09-8.01). Furthermore, the COR for the interaction between GSTT null and industrial plants within 50 m was 5.99 (95% CI: 1.41-25.45). Our results suggest an association between proximity to industrial plants and the GSTT null allele in patients with childhood AL.

Clusters and clustering of childhood cancer: a review

Methodological considerations in the study of clusters and clustering of childhood cancer are reviewed briefly. A selection of 11 studies of individual clusters of childhood leukaemia which are either particularly notable or recent and have been reported in peer review journals is then considered. Focus is placed on sources of alerts, descriptive studies, field-work studies, conclusions and communication management. Some of these studies are probably essential but they are unlikely to yield firm conclusions; studies of large data sets are recommended. No causal factor has been identified which can explain a single cluster of childhood leukaemia.

Analysis of risk factors in a cluster of childhood acute lymphoblastic leukemia

A case-control investigation of childhood acute lymphoblastic leukemia was conducted in the town of Carbonia (Sardinia, Italy). Parents of 9 cases diagnosed between 1980 and 1989 and 36 controls were interviewed at their respective residences. None of the risk factors analyzed was associated significantly with childhood acute lymphoblastic leukemia. The following were associated with an increased risk for childhood acute lymphoblastic leukemia: parents born outside of Carbonia, family history of cancer, alcohol consumption by fathers that exceeded 60 g/d, exposure of fathers to solvents at their workplaces, maternal smoking, use of antinausea medications during pregnancy, and presence of a well in the backyard. Chance and recall bias likely played a role in generating positive associations. The increases in childhood leukemia risk associated with the presence of a well and with use of antinausea medications during pregnancy are consistent with previous reports and require further investigation.