Exposure to medical test irradiation and acute leukemia among children with Down syndrome: a report from the Children's Oncology Group

Childhood cancer risk in those with chromosomal and non-chromosomal congenital anomalies in Washington State: 1984-2013

Background

The presence of a congenital anomaly is associated with increased childhood cancer risk, likely due to large effects of Down syndrome and chromosomal anomalies for leukemia. Less is known about associations with presence of non-chromosomal anomalies.

Methods

Records of children diagnosed with cancer at <20 years of age during 1984–2013 in Washington State cancer registries were linked to their birth certificates (N = 4,105). A comparison group of children born in the same years was identified. Congenital anomalies were assessed from birth records and diagnosis codes in linked hospital discharge data. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for cancer, and for specific cancer types in relation to the presence of any anomaly and specific anomalies.

Results

Having any congenital anomaly was associated with an increased risk of childhood cancer (OR: 1.46, 95% CI 1.28–1.65). Non-chromosomal anomalies were also associated with increased childhood cancer risk overall (OR: 1.35; 95% CI: 1.18–1.54), and with increased risk of several cancer types, including neuroblastoma, renal, hepatoblastoma, soft-tissue sarcoma, and germ cell tumors. Increasing number of non-chromosomal anomalies was associated with a stronger risk of childhood cancer (OR for 3+ anomalies: 3.11, 95% CI: 1.54–6.11). Although central nervous system (CNS) anomalies were associated with CNS tumors (OR: 6.05, 95% CI 2.75–13.27), there was no strong evidence of other non-chromosomal anomalies being specifically associated with cancer occurring in the same organ system or anatomic location.

Conclusions

Non-chromosomal anomalies increased risk of several cancer types. Additionally, we found that increasing number of non-chromosomal anomalies was associated with a stronger risk of cancer. Pooling similar data from many regions would increase power to identify specific associations in order to inform molecular studies examining possible common developmental pathways in the etiologies of birth defects and cancer.

Immune-related conditions and acute leukemia in children with Down syndrome: a Children's Oncology Group report

BACKGROUND

Children with Down syndrome have unique immune profiles and increased leukemia susceptibility.

METHODS

Mothers of 158 children with Down syndrome diagnosed with acute leukemia at 0 to 19 years in 1997 to 2002 and 173 children with Down syndrome but no leukemia were interviewed. Associations were evaluated via multivariable unconditional logistic regression.

RESULTS

No associations were detected for asthma, eczema, allergies, or hypothyroidism. Diabetes mellitus associated with leukemia (OR = 9.23; 95% confidence interval 2.33-36.59); however, most instances occurred concurrent with or after the leukemia diagnosis.

CONCLUSIONS AND IMPACT

Children with Down syndrome who develop leukemia have increased diabetes risk, likely due to treatment and underlying susceptibility factors.

Genomics of racial and ethnic disparities in childhood acute lymphoblastic leukemia

Although the cure rates of childhood acute lymphoblastic leukemia (ALL) have improved dramatically in the past 40 years, not all children have benefited equally from this impressive progress. Racial and ethnic disparities in the incidence and treatment outcome of childhood ALL persist, with Hispanic children having an elevated risk of developing ALL and one of the lowest survival rates after ALL therapy. A critical barrier to progress is the lack of an understanding of the causes of ALL disparities, particularly racial and ethnic differences in ALL biology. In this review, the authors summarize the current knowledge on population variation in childhood ALL incidence and treatment outcome, discuss the contributing genetic and nongenetic variables, and highlight possible therapeutic interventions to mitigate disparities in ALL.

Are children with birth defects at higher risk of childhood cancers?

Birth defects may influence the risk of childhood cancer development through a variety of mechanisms. The rarity of both birth defects and childhood cancers makes it challenging to study these associations, particularly for the very rare instances of each. To address this limitation, the authors conducted a record linkage-based cohort study among Texas children born between 1996 and 2005. Birth defects in the cohort were identified through the Texas Birth Defects Registry, and children who developed cancer were identified by using record linkage with Texas Cancer Registry data. Over 3 million birth records were included; 115,686 subjects had birth defects, and there were 2,351 cancer cases. Overall, children with a birth defect had a 3-fold increased risk of developing cancer (incidence rate ratio (IRR) = 3.05, 95% confidence interval (CI): 2.65, 3.50), with germ cell tumors (IRR = 5.19, 95% CI: 2.67, 9.41), retinoblastomas (IRR = 2.34, 95% CI: 1.21, 4.16), soft-tissue sarcomas (IRR = 2.12, 95% CI: 1.09, 3.79), and leukemias (IRR = 1.39, 95% CI: 1.09, 1.75) having statistically significant elevated point estimates. All birth defect groups except for musculoskeletal had increased cancer incidence. Untangling the strong relation between birth defects and childhood cancers could lead to a better understanding of the genetic and environmental factors that affect both conditions.

Diagnostic X-rays and risk of childhood leukaemia

BACKGROUND

The association between diagnostic X-ray exposures early in life and increased risk of childhood leukaemia remains unclear.

METHODS

This case-control study included children aged 0-14 years diagnosed with acute lymphoid leukaemia (ALL, n = 711) or acute myeloid leukaemia (AML, n = 116) from 1995 to 2008. Controls were randomly selected from the California birth registry and individually matched to cases with respect to date of birth, sex, Hispanic ethnicity and maternal race. Conditional logistic regression analyses were performed to assess whether ALL or AML was associated with self-reported child's X-rays after birth (post-natal), including number of X-rays, region of the body X-rayed and age at first X-ray, as well as maternal X-rays before and during pregnancy (preconception and prenatal).

RESULTS

After excluding X-rays in the year prior to diagnosis (reference date for matched controls), risk of ALL was elevated in children exposed to three or more post-natal X-rays [odds ratio (OR) = 1.85, 95% confidence interval (CI) 1.12-2.79]. For B-cell ALL specifically, any exposure (one or more X-rays) conferred increased risk (OR = 1.40, 95% CI 1.06-1.86). Region of the body exposed was not an independent risk factor in multivariable analyses. No associations were observed between number of post-natal X-rays and AML (OR = 1.05, 95% CI 0.90-1.22) or T-cell ALL (OR = 0.84, 95% CI 0.59-1.19). Prevalence of exposure to prenatal and preconception X-rays was low, and no associations with ALL or AML were observed.

CONCLUSIONS

The results suggest that exposure to post-natal diagnostic X-rays is associated with increased risk of childhood ALL, specifically B-cell ALL, but not AML or T-cell ALL. Given the imprecise measures of self-reported X-ray exposure, the results of this analysis should be interpreted with caution and warrant further investigation.

Down syndrome and malignancies: a unique clinical relationship: a paper from the 2008 william beaumont hospital symposium on molecular pathology

The patterns of malignancies in Down syndrome (DS) are unique and highlight the relationship between chromosome 21 and cancer. DS children have a approximately 10- to 20-fold higher risk for developing acute lymphoblastic leukemia and acute myeloid leukemia (AML), as compared with non-DS children, although they do not have a uniformly increased risk of developing solid tumors. DS children with acute lymphoblastic leukemia frequently experience higher levels of treatment-related toxicity and inferior event-free survival rates, as compared with non-DS children. DS children also develop AML with unique features and have a 500-fold increased risk of developing the AML subtype, acute megakaryocytic leukemia (AMkL; M7). Nearly 10% of DS newborns are diagnosed with a variant of AMkL, the transient myeloproliferative disorder, which can resolve spontaneously without treatment; event-free survival rates for DS patients with AMkL ranges from 80% to 100%, in comparison with <30% for non-DS children with AMkL. In addition, somatic mutations of the GATA1 gene have been detected in nearly all DS TMD and AMkL cases and not in leukemia cases in non-DS children. GATA1 mutations are key factors linked to both leukemogenesis and the high cure rates of DS AMkL patients. Identifying the mechanisms that account for the high event-free survival rates of DS AMkL patients may ultimately improve AML treatment as well. Examining leukemogenesis in DS children may identify factors linked to the general development of childhood leukemia and lead to potential new therapeutic strategies to fight this disease.

Breastfeeding and early infection in the aetiology of childhood leukaemia in Down syndrome

Background:

For a child to develop acute leukaemia (AL), environmental exposure may not be sufficient: interaction with a susceptibility factor to the disease, such as Down syndrome (DS), may also be necessary. We assessed whether breastfeeding and early infection were associated with the risk of developing AL in children with DS.

Methods:

Children with DS in Mexico City, and either with or without AL, were the cases (N=57) and controls (N=218), respectively. Population was divided in children with AL and with acute lymphoblastic leukaemia (ALL) and also in children ⩽6 and >6 years old.

Results:

Breastfeeding and early infections showed moderate (but not significant) association for AL, whereas hospitalisation by infection during the first year of life increased the risk: odds ratios (confidence interval 95%) were 0.84 (0.43–1.61), 1.70 (0.82–3.52); and 3.57 (1.59–8.05), respectively. A similar result was obtained when only ALL was analysed.

Conclusion:

We found that breastfeeding was a protective factor for developing AL and ALL, and during the first year of life, infections requiring hospitalisation were related to a risk for developing the disease in those children with DS >6 years of age. These data do not support the Greaves's hypothesis of early infection being protective for developing ALL.

Maternal health conditions during pregnancy and acute leukemia in children with Down syndrome: A Children's Oncology Group study

BACKGROUND

Children with Down syndrome (DS) have about a 20-fold increased risk of developing leukemia. Early childhood infections may protect against acute lymphoid leukemia (ALL) in children with and without DS. We examined whether maternal infections and health conditions during pregnancy were associated with acute leukemia in children with DS.

PROCEDURE

We conducted a case-control study of 158 children with DS and leukemia (including 97 cases with acute lymphoblastic leukemia (ALL) and 61 cases with acute myeloid leukemia (AML)) and 173 children with DS during the period 1997-2002. Maternal interview included information about 14 maternal conditions during gestation that are likely to induce an inflammatory response. We evaluated their prevalence in cases and controls. Five of these were common enough to allow analyses by leukemia subtype.

RESULTS

Vaginal bleeding was the most frequent (18% cases, 25% controls) and was associated with a reduced risk (odds ratio (OR) = 0.57; 95% confidence interval (CI) = 0.33-0.99) for all cases combined. Other variables, while showing a potential trend toward reduced risk had effect estimates, which were imprecise and not statistically significant. In contrast, amniocentesis was marginally associated with an increased risk of AML (OR = 2.06, 95% CI = 0.90-4.69).

CONCLUSIONS

Data from this exploratory investigation suggest that some health conditions during pregnancy may be relevant in childhood leukemogenesis. Larger epidemiological studies and other model systems (animal, clinical studies) may provide a clearer picture of the potential association and mechanisms.

Malignancy in children with trisomy 21

Patients with Down syndrome (DS) display a unique spectrum of malignancies, with a 10- to 20-fold higher risk of acute leukemias, and a markedly lower incidence of solid tumors. This review discusses the current understanding of the basis for this distinctive pattern of cancer incidence and the clinical and biologic features of the malignant disorders most frequent in DS individuals: transient myeloproliferative disease, acute megakaryoblastic leukemia, and acute lymphoblastic leukemia. We also review distinctive pharmacogenetic issues, highlighting the differential chemosensitivity and toxicity profiles of DS patients compared with the general population, and epidemiologic studies of protective and adverse environmental risk factors for the development of leukemia.

Congenital abnormalities and acute leukemia among children with Down syndrome: a Children's Oncology Group study

Children with Down syndrome, due to their heightened risk of leukemia and increased prevalence of congenital abnormalities, comprise a valuable population in which to study etiology. A Children's Oncology Group study investigated the causes of childhood leukemia in children with Down syndrome diagnosed at ages 0 to 19 years during the period 1997-2002. Telephone interviews were completed with mothers of 158 cases [n=97 acute lymphoblastic leukemia (ALL) and n=61 acute myeloid leukemia (AML)] and 173 controls. Odds ratios (OR) and 95% confidence intervals (95% CI) were computed via unconditional logistic regression to evaluate the association between congenital abnormalities and acute leukemia overall, and ALL and AML analyzed separately. The results do not provide evidence for an association among the index children (OR(Combined), 0.74; 95% CI, 0.45-1.23; OR(ALL), 0.67; 95% CI, 0.38-1.20; OR(AML),1.03; 95% CI, 0.49-2.16) or their siblings (OR(Combined), 1.23; 95% CI, 0.71-2.13; OR(ALL), 1.12; 95% CI, 0.60-2.09; OR(AML), 1.60; 95% CI, 0.66-3.86), suggesting congenital malformations do not confer additional risk of leukemia beyond the risk attributable to trisomy 21 in this population.