Trends in childhood cancer incidence and mortality in urban Shanghai, 1973-2005

Indoor volatile organic compounds exposures and risk of childhood acute leukemia: a case-control study in shanghai

A case-control study was conducted to investigate the relationship between indoor air pollution and childhood acute leukemia (AL) in Shanghai. 97 cases and 148 gender-, age-, and residence-matched controls were included. Indoor air pollution was evaluated by questionnaires and quantitative measurement including 14 volatile organic compounds (VOCs) and nitrogen dioxide (NO₂) in the homes of the two groups. The levels of individual VOCs, VOC families, TVOC (sum of the concentrations of the individual VOCs) and NO₂ were compared between the two groups. Exposure to styrene and butyl alcohol were associated with an increased risk of childhood AL (styrene: odds ratio (OR)=2.33, 95% confidence interval (CI): 1.07-5.07; butyl alcohol: OR = 2.51, 95%CI: 1.19-5.28); 4th quartile of chlorinated hydrocarbons (OR = 2.52, 95%CI: 1.02-6.26) and 3rd quartile of TVOC (OR = 4.03, 95%CI: 1.06-6.81) had significant higher ORs for childhood AL compared with that in the lowest quartiles. Elevated levels of individual VOCs, VOC families and TVOC were also associated with self-reported risk factors. Our findings suggest that VOCs exposure was associated with an elevated risk of childhood AL, underscore that more attention should be paid to indoor air pollution as a risk factor of childhood AL.

Characteristics and trends of childhood cancer in Pudong, China, 2002-2015

Background

With the growing threat of cancer to children’s health, it is necessary to analyze characteristics and trends of childhood cancer to formulate better cancer prevention strategies.

Methods

Data on the 430 children with cancer during 2002–2015 were collected from the Pudong Cancer Registry, diagnosed with the International Classification of Diseases for Oncology and categorized according to the International Classification of Childhood Cancer. The incidence rate, trends over time, and survival of patients grouped by sex, age, and region were explored using the Kaplan-Meier, Cox regression, and Joinpoint Regression models.

Results

The crude childhood cancer incidence and world age-standardized incidence rate (ASR) were 115.1/1,000,000 and 116.3/1,000,000 person-years. The two most frequent cancers were leukemia (136/430, 31.63%, ASR, 37.8/1,000,000 person-years) and central nervous system (CNS) tumors (86/430, 20.00%, ASR, 22.9/1,000,000 person-years). Our findings indicate that the survival rate for children between 10 and 15 years of age was higher than that for 5–10; and the survival rate for children who had leukemia was higher than that of children with CNS tumors. However, the overall incidence of childhood cancer, and leukemia, CNS tumors remained relatively stable in Pudong between 2002 and 2015.

Conclusions

The incidence and survival rate for childhood cancer patients varied by age and cancer type. The overall trends of childhood cancer incidence remained relatively stable in Pudong from 2002 to 2015 even though socioeconomic development has been unprecedentedly fast in this region.

Identification of clinical molecular targets for childhood Burkitt lymphoma

Burkitt lymphoma (BL) is a malignant tumor in children. Although BL is generally curable, early relapse and refractoriness may occur. Some molecular indicators have been recently suggested for BL diagnosis, but large heterogeneity still exists. This study aimed at providing clinical molecular targets and methods that may help improve diagnosis and treatment of childhood BL. Only children patients were included in the study, and targeted gene sequencing was conducted to identify tumor specific mutations. The mRNA and protein level expression of potential target genes were measured by real-time PCR and immunohistochemistry. The relationship between BL specific gene mutation and differential expression with clinical features was analyzed. The results showed that i) detailed analysis of c-MYC/BCL2/BCL6 gene loci alteration and gene expression would help in accurate diagnosis and treatment determination of childhood BL; ii) loss-of-function mutations in SOCS1 or CIITA gene might be used as malignant markers for BL diagnosis and prognosis; iii) specific mutations of CD79A, MYD88, KLF2, DNMT3A and NFKBIE genes often concurrently existed in BL and showed association with benign clinical outcomes; iv) the high expression of MYC, TCF3 and loss-of-function ID3 genes in tumor may be potential therapeutic targets and could be used for treatment monitoring; and v) four MYC-translocation negative cases were re-defined as high-grade B-cell lymphoma-not otherwise specified (HGBL-NOS) but showed similar clinical outcomes and molecular features to other BL cases in the study, suggesting more studies needed to explore the molecular mechanisms and clinical significance of this provisional tumor entity.

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Detailed analysis of c-MYC/BCL2/BCL6 gene alteration and expression may help in accurate diagnosis and treatment;

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The MYC-translocation negative cases (HGBL-NOS) showed similar clinical outcomes and molecular features to other cases;

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Loss-of-function mutations of SOCS1 or CIITA gene could be used as malignant markers for diagnosis and prognosis;

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Concurrent mutations in CD79A, MYD88, KLF2, DNMT3A and NFKBIE genes associated with benign clinical outcomes;

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High expression of MYC, TCF3 and loss-of-function ID3 gene in tumor may be potential therapeutic targets.

Methodological approaches to the study of cancer risk in the vicinity of pollution sources: the experience of a population-based case-control study of childhood cancer

Background

Environmental exposures are related to the risk of some types of cancer, and children are the most vulnerable group of people. This study seeks to present the methodological approaches used in the papers of our group about risk of childhood cancers in the vicinity of pollution sources (industrial and urban sites). A population-based case–control study of incident childhood cancers in Spain and their relationship with residential proximity to industrial and urban areas was designed. Two methodological approaches using mixed multiple unconditional logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) were developed: (a) “near vs. far” analysis, where possible excess risks of cancers in children living near (“near”) versus those living far (“far”) from industrial and urban areas were assessed; and (b) “risk gradient” analysis, where the risk gradient in the vicinity of industries was assessed. For each one of the two approaches, three strategies of analysis were implemented: “joint”, “stratified”, and “individualized” analysis. Incident cases were obtained from the Spanish Registry of Childhood Cancer (between 1996 and 2011).

Results

Applying this methodology, associations between proximity (≤ 2 km) to specific industrial and urban zones and risk (OR; 95% CI) of leukemias (1.31; 1.04–1.65 for industrial areas, and 1.28; 1.00–1.53 for urban areas), neuroblastoma (2.12; 1.18–3.83 for both industrial and urban areas), and renal (2.02; 1.16–3.52 for industrial areas) and bone (4.02; 1.73–9.34 for urban areas) tumors have been suggested.

Conclusions

The two methodological approaches were used as a very useful and flexible tool to analyze the excess risk of childhood cancers in the vicinity of industrial and urban areas, which can be extrapolated and generalized to other cancers and chronic diseases, and adapted to other types of pollution sources.

Time and spatial trends in lymphoid leukemia and lymphoma incidence and survival among children and adolescents in Manitoba, Canada: 1984-2013

OBJECTIVES

To test for time and spatial trends in lymphoid malignancies, including lymphoid leukemia (LL), Hodgkin lymphoma (HL), and non-Hodgkin lymphoma (NHL), in children and adolescents in the province of Manitoba, Canada.

METHODS

Incident cases diagnosed between 1984 and 2013 were identified from the Manitoba Cancer Registry. We assessed time trends in age-standardized incidence rates using joinpoint regression and in 5-year relative survival using Poisson regression model. Kulldorff's scan method was used to assess spatial variation and clustering.

RESULTS

Age-standardized incidence rates (per million person-years) in males and females were 34.0 (95% confidence interval [CI] 28.9-39.1) and 26.2 (95% CI 21.5-30.7) for LL, 10.5 (95% CI 7.7-13.3) and 12.5 (95% CI 9.4-15.7) for HL, 12.5 (95% CI 9.3-15.4) and 7.7 (95% CI 5.2-10.2) for NHL (except for Burkitt lymphomas), and 3.2 (95% CI 1.6-4.7) and 1.5 (95% CI 0.4-2.5) for Burkitt lymphomas. Age- and sex- standardized LL incidence rate increased 1.4% (95% CI 0.3%-2.5%) per year, while the changes for HL and NHL incidence rates were not statistically significant. There were geographic differences in age-standardized incidence rates for LL, HL, and NHL and spatial clusters were detected in southern part of the province. Five-year relative survival has improved over time and there was no difference between rural and urban areas.

CONCLUSIONS

Lymphoid leukemia incidence rate increased over time and varied by geographic area. Further research should examine the factors contributing to these trends.

Risk of bone tumors in children and residential proximity to industrial and urban areas: New findings from a case-control study

Few epidemiologic studies have explored risk factors for bone tumors in children, and the role of environmental factors needs to be analyzed. Our objective was to ascertain the association between residential proximity to industrial plants and urban areas and risk of bone tumors in children, taking into account industrial groups and toxic pollutants released. A population-based case-control study of childhood bone cancer in Spain was carried out, covering 114 incident cases obtained from the Spanish Registry of Childhood Tumors (between 1996 and 2011), and 684 controls individually matched by sex, year of birth, and autonomous region of residence. Distances from the subject's residences to the 1271 industries and the 30 urban areas (towns) with ≥75,000 inhabitants located in the study area were computed. Unconditional logistic regression models were fitted to estimate odds ratios (ORs) and 95% confidence intervals (95%CIs) for categories of distance (from 1km to 3km) to industrial and urban areas, with adjustment for matching variables and sociodemographic indicators. Excess risk (OR; 95%CI) of bone tumors in children was detected for children close to industrial facilities as a whole (2.33; 1.17-4.63 at 3km) - particularly surface treatment of metals (OR=2.50; 95%CI=1.13-5.56 at 2km), production and processing of metals (OR=3.30; 95%CI=1.41-7.77 at 2.5km), urban waste-water treatment plants (OR=4.41; 95%CI=1.62-11.98 at 2km), hazardous waste (OR=4.63; 95%CI=1.37-15.61 at 2km), disposal or recycling of animal waste (OR=4.73; 95%CI=1.40-15.97 at 2km), cement and lime (OR=3.89; 95%CI=1.19-12.77 at 2.5km), and combustion installations (OR=3.85; 95%CI=1.39-10.66 at 3km)-, and urban areas (4.43; 1.80-10.92). These findings support the need for more detailed exposure assessment of certain toxics released by these facilities.

Incidence and Survival of Childhood Cancer in Korea

Purpose

An epidemiologic study of childhood cancer would provide useful information on cancer etiology and development of management guidelines.

Materials and Methods

Data from the Korea National Cancer Incidence Database were used to examine the incidence and survival of cancer in patients aged 0-14 years. Patients were grouped according to the International Classification of Childhood Cancer, 3rd edition. Age-specific and age-standardized incidences per million and estimated annual percentage change (APC) were calculated by sex and age. Five-year relative survival was calculated for four periods from 1993 to 2011.

Results

The study comprised 15,113 patients with malignant neoplasms. Age-standardized incidence rates for all cancers were 134.9 per million children in 1999-2011 and 144.0 and 124.9 per million for males and females, respectively (M/F ratio, 1.2; p < 0.05). The highest incidences were observed for ‘leukemias, myeloproliferative diseases, and myelodysplastic diseases’ (group I) (46.4), ‘central nervous system neoplasms’ (group III) (18.3), and ‘lymphomas and reticuloendothelial neoplasms’ (group II) (13.4). Age-standardized incidence increased from 117.9 in 1999 to 155.3 in 2011, with an APC of 2.4% (95% confidence interval, 2.1 to 2.7). There was a significant increase of APC in ‘neuroblastoma and other peripheral nervous cell tumors’ (group IV) (5.6%) and ‘other malignant epithelial neoplasms and malignant melanomas’ (group XI) (5.6%). The 5-year relative survival rate for all childhood cancers improved significantly from 56.2% (1993-1995) to 78.2% (2007-2011) (males, 56.7% to 77.7%; females, 55.5% to 78.8%).

Conclusion

This study provides reliable information on incidence and survival trends for childhood cancer in Korea.

International long-term trends and recent patterns in the incidence of leukemias and lymphomas among children and adolescents ages 0-19 years

To enhance understanding of etiology, we examined international population-based cancer incidence data for lymphoid leukemia, non-Hodgkin lymphoma, Hodgkin lymphoma and myeloid leukemia among children aged 0-19. Based on temporal trends during 1978-2007 in 24 populations, lymphoid leukemia and myeloid leukemia incidence rates generally have not changed greatly and differences in rates for non-Hodgkin and for Hodgkin lymphoma have diminished in some regions. Lymphoid leukemia rates during 2003-2007 in 54 populations varied about 10-fold, with rates highest in US white Hispanics (50.2 per million person-years) and Ecuador (48.3) and lowest in US blacks (20.4), Tunisia (17.7) and Uganda (6.9). Non-Hodgkin lymphoma rates varied 30-fold, with very high rates in sub-Saharan Africa (146.0 in Malawi and 54.3 in Uganda) and low rates (≤ 10) in some Asian populations (China, Japan, India, the Philippines and Thailand) and U.S. Asian-Pacific Islanders, eastern and northern European populations and Puerto Rico. Hodgkin lymphoma rates varied 15-fold, with rates highest in Italy (21.3) and lowest in China (1.7). Myeloid leukemia rates varied only about fivefold, with rates highest in the Philippines and Korea (exceeding 14.0) and lowest in Eastern Europe (5.9 in Serbia and 5.3 in the Czech Republic) and Uganda (2.7). The boy/girl average incidence rate ratios were 2.00 or lower. Age-specific patterns differed among the four hematopoietic malignancies, but were generally consistent within major categories world-wide, except for non-Hodgkin lymphoma. A systematic world-wide approach comparing postulated etiologic factors in low- versus high-risk populations may help clarify the etiology of these childhood malignancies.

Differences in childhood leukemia incidence and survival between Southern Thailand and the United States: a population-based analysis

BACKGROUND

Childhood leukemia incidence and survival varies globally, and this variation may be attributed to environmental risk factors, genetics, and/or disparities in diagnosis and treatment.

PROCEDURE

We analyzed childhood leukemia incidence and survival trends in children aged 0-19 years from 1990 to 2011 in Songkhla, Thailand (n = 316) and compared these results to US data from the Surveillance, Epidemiology, and End Results (SEER) registry (n = 6,738). We computed relative survival using Ederer II and estimated survival functions using the Kaplan-Meier method. Changes in incidence and 5-year survival by year of diagnosis were evaluated using joinpoint regression and are reported as annual percent changes (APC).

RESULTS

The age-standardized incidence of leukemia was 3.2 and 4.1 cases per 100,000 in Songkhla and SEER-9, respectively. In Songkhla, incidence from 1990 to 2011 significantly increased for leukemia (APC = 1.7%, P = 0.031) and acute lymphoblastic leukemia (ALL) (APC = 1.8%, P = 0.033). Acute myeloid leukemia (AML) incidence significantly increased (APC = 4.2%, P = 0.044) and was significantly different from the US (P = 0.026), where incidence was stable during the same period (APC = 0.3%, P = 0.541). The overall 5-year relative survival for leukemia was lower than that reported in the US (43 vs. 79%). Five-year survival significantly improved by at least 2% per year from 1990 to 2011 in Songkhla for leukemia, ALL, and AML (P < 0.050).

CONCLUSIONS

While leukemia and ALL incidence increased in Songkhla, differences in leukemia trends, particularly AML incidence, may suggest etiologic or diagnostic differences between Songkhla and the US. This work highlights the importance of evaluating childhood cancer trends in low- and middle-income countries.

Cancer incidence rates and trends among children and adolescents in the United States, 2001-2009

OBJECTIVES

Cancer continues to be the leading disease-related cause of death among children and adolescents in the United States. More current information is needed to describe recent cancer trends and identify demographic and geographic variations.

METHODS

We analyzed data from the National Program of Cancer Registries and Surveillance, Epidemiology, and End Results statewide registries representing 94.2% of the US population to identify cancers diagnosed among persons aged 0 to 19 years during 2001-2009. Age-adjusted rates and annual percentage change for trends were calculated. Data were stratified by age, gender, race, ethnicity, and geography.

RESULTS

We identified 120,137 childhood and adolescent cancer cases during 2001-2009 with an age-adjusted incidence rate of 171.01 per million. The overall rate of all cancers combined remained stable over time (annual percent change [APC], 0.3%; 95% confidence interval [CI], -0.1 to 0.7). There was an increase in the overall cancer trend among African American children and adolescents (APC, 1.3%; 95% CI, 0.2 to 2.5). An increasing trend for thyroid cancer was observed among both genders (APC, 4.9%; 95% CI, 3.2 to 6.6) and specifically among adolescents and those in the Northeast, South, and West regions of the United States. Renal carcinoma incidence was increasing significantly overall (APC, 5.4%; 95% CI, 2.8 to 8.1). Extracranial and extragonadal germ cell tumors and melanoma were both significantly decreasing.

CONCLUSIONS

This study reports the novel finding that renal carcinoma rates are increasing among children and adolescents. This study confirms that thyroid cancer rates are increasing and further describes rising cancer rates among African Americans.

Characteristics and trends in incidence of childhood cancer in Beijing, China, 2000-2009

OBJECTIVE

To investigate the characteristics and incidence trends of childhood cancer in Beijing, China, from 2000 to 2009.

METHODS

A total of 1,274 cases with childhood cancer in Beijing from 2000 to 2009 were included in the study. All rates were age-standardized using the direct method to the world standard population and expressed per million person-years. Incidence trends were characterized by calculating annual percent change (APC) using Joinpoint Regression Program.

RESULTS

The crude incidence rate was 106.47 per million [age-standardized rate (ASR) 113.34] between 2000 and 2009 in Beijing with the most common diagnoses, leukemia (N=505, 39.64%, ASR 45.20), followed by central nervous system (CNS) tumors (N=228, 17.90%, ASR 19.28) and lymphoma (N=91, 7.14%, ASR 6.97). The incidence for all childhood cancers combined has increased during the study period, with an APC of 5.84% [95% confidence interval (95% CI): 1.0-10.9] after adjusted by world population. The ASR of all combined cancers in boys showed a slight, but no significant increase, with an APC of 5.33% (95% CI: -0.6-11.6); for girls, the trends increased significantly, with an APC of 6.54% (95% CI: 1.5-11.8).

CONCLUSIONS

The incidence rate of childhood cancer in Beijing was higher than the average level of China and lower than that of western countries. The incidence trends of childhood cancer, especially leukemia among girls showed a significantly increase from 2000 to 2009. While among boys, no substantially change was seen during the observed time period. Some sex-specific trends by subcategories and trends of major cancers in different age groups by cancer site merit further investigation.

Population-based survival for childhood cancer patients diagnosed during 2002-2005 in Shanghai, China

BACKGROUND

There have been no population-based studies on cancer survival among children aged 0-14 years in China. In this study, we aimed to characterize the cancer survival among children in Shanghai.

PROCEDURE

Childhood cancer cases registered by the Shanghai Cancer Registry between 2002 and 2005 and enrolled in the Shanghai Childhood Survival Study were included in this study. We used Kaplan-Meier product-limit method for survival analysis and Cox proportional hazards models for investigating the effects of various prognostic factors.

RESULTS

The median follow-up time was 5.4 years (range 0-8.9 years). The 5-year observed survival for all childhood cancers combined was 55.7% (95% CI: 51.7-59.6%). For leukemia, lymphoma, and central nervous system tumors, the three most common types of childhood cancer, 5-year survival rates were 52.2%, 58.8%, and 41.2%, respectively. Higher 5-year survival rates were observed for epithelial cancer (88.9%), malignant renal tumors (86.7%), germ cell and other gonadal tumors (78.4%), and retinoblastoma (75.0%). Cancers with poor prognosis included sympathetic nervous system tumors (57.9%), soft tissue sarcoma (54.1%), bone tumors (52.6%), and liver cancer (33.3%). There were no significant differences between survival rates by gender and age groups. Compared with those reported in the USA and Europe, the survival rates for all cancers combined and the three most common types in Shanghai were lower.

CONCLUSIONS

The survival rate for children aged 0-14 diagnosed with cancer in Shanghai during 2002-2005 was at the medium level. There was a substantial survival difference from childhood cancers between Shanghai and specific developed countries.

Cancer incidence among adolescents and young adults in urban Shanghai, 1973-2005

BACKGROUND

Lack of cancer incidence information for adolescents and young adults led us to describe incidence trends within the young population of 15 to 49 year-olds in urban Shanghai between 1973 and 2005.

METHODS

During 1973 to 2005, data on 43,009 (45.8%) male and 50,828 (54.2%) female cancer cases aged 15-49 years from the Shanghai Cancer Registry were analyzed. Five-year age-specific rates, world age-standardized rates, percent change (PC), and annual percent change (APC) were calculated using annual data on population size and its estimated age structure.

RESULTS

During the 33-year study period, overall cancer incidence of adolescents and young adults among males marginally decreased by 0.5% per year (P<0.05). However, overall cancer incidence for females slightly increased by 0.8% per year (P<0.05). The leading cancer for males in rank were liver, stomach, lung, colorectal, and nasopharyngeal cancers and for females were breast, stomach, colorectal, thyroid, and ovarian cancers. Among specific sites, incidence rates significantly decreased for cancers of the esophagus, stomach, and liver in both sexes. In contrast, incidence rates significantly increased for kidney cancers, non-Hodgkin lymphoma, and brain and nervous system tumors in both sexes and increased for breast and ovarian cancers among females.

CONCLUSIONS

Overall cancer incidence rates of adolescents and young adults decreased in males whereas they increased in females. Our findings suggest the importance of further epidemiology and etiologic studies to further elucidate factors contributing to the cancer incidence trends of adolescents and young adults in China.

Perinatal and family risk factors for non-Hodgkin lymphoma in early life: a Swedish national cohort study

BACKGROUND

The incidence of non-Hodgkin lymphoma (NHL) in early life has increased in recent decades, but the relevant risk factors remain largely unknown. We examined perinatal and family risk factors for NHL in childhood through young adulthood.

METHODS

We conducted a national cohort study of 3 571 574 individuals born in Sweden in 1973-2008 who were followed for incidence of NHL through 2009 (ages 0-37 years). Detailed information on perinatal and family characteristics and NHL diagnoses were obtained from national birth and cancer registries. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between perinatal and family variables and NHL; P values are from two-sided tests.

RESULTS

There were 936 NHL case patients identified in 66.3 million person-years of follow-up. Independent risk factors for NHL included family history of NHL in either a sibling (adjusted HR = 9.84; 95% CI = 2.46 to 39.41; P = .001) or parent (adjusted HR = 2.36; 95% CI = 1.27 to 4.38; P = .007); high fetal growth (for ≥ 2 SDs relative to 0 to <1 SD from the mean: adjusted HR = 1.64; 95% CI = 1.19 to 2.25; P = .002); older maternal age (adjusted HR for each 5-year increment = 1.11; 95% CI = 1.04 to 1.19; P (trend) = .004); low birth order (adjusted HR for each increment of one birth = 0.91; 95% CI = 0.84 to 0.99; P (trend) = .02); and male sex (adjusted HR = 1.58; 95% CI = 1.38 to 1.80; P < .001). Male sex was associated with onset of NHL before 15 years of age but not with later-onset NHL, whereas the other risk factors did not vary by age at diagnosis. No association was found between gestational age at birth, twinning, paternal age, or parental education and NHL.

CONCLUSION

In this large national cohort study, family history of NHL, high fetal growth, older maternal age, low birth order, and male sex were independent risk factors for NHL in early life.

International trends in liver cancer incidence rates

BACKGROUND

Several previous studies have documented region or country-specific liver cancer incidence trends around the world. However, no study has systematically examined the international pattern using the most recently updated incidence data from the International Agency for Research on Cancer.

METHODS

We examined recent trends in liver cancer incidence rates from 1993 to 2002 by joinpoint analysis for 32 cancer registries worldwide, using Cancer Incidence in Five Continents. We also examined the male to female rate ratios for these and four additional registries, based on the 1998-2002 incidence data.

RESULTS

Liver cancer incidence rates for both men and women statistically significantly increased from 1993 to 2002 for 8 of 32 cancer registries considered in the analysis. Increases were largely confined to economically developed countries of Western Europe, North America, and Oceania. In contrast, rates decreased in both men and women in 5 registries including 3 in Asia. Despite this, the incidence rates in Asian countries are twice as high as those in Africa and more than four times as high as rates in North America. Male to female rate ratios varied from 0.9 in sub-Saharan African and South American registries to 5.0 in France and Egypt.

CONCLUSIONS

Liver cancer incidence rates continue to increase in some low-risk parts of the world whereas they are decreasing in some of the highest risk countries in Asia. Etiologic studies are required to further elucidate factors contributing to the divergent liver cancer incidence trends worldwide.

IMPACT

Our description of international liver cancer incidence trends may stimulate further etiologic studies.

Childhood cancer mortality and birth characteristics in Korea: a national population-based birth cohort study

To examine the relationship between birth characteristics and childhood cancer mortality, a retrospective cohort study of Korean children was conducted using data collected by the national birth register between 1995 and 2006, which were then individually linked to death data. A cohort of 6,479,406 children was followed from birth until their death or until December 31, 2006. Poisson regression analyses were used to calculate rate ratios of childhood cancer deaths according to birth characteristics. A total of 1,469 cancer deaths were noted and the childhood cancer mortality rate was found to be 3.43 per 100,000 person-years in Korea during the period of 1995-2006. The birth characteristics examined in this study (i.e. , birth weight, gestational age, multiple births, parental ages, and number of siblings) were generally found to be not significantly associated with childhood cancer mortality, and the associations did not vary meaningfully with gender nor with cancer sites. However, among children aged 5-11 yr, higher birth weight was associated with elevated childhood cancer mortality (rate ratio = 1.28, 95% confidence interval 1.04-1.58). Our results offer no overall associations between childhood cancer mortality and birth characteristics, but suggest that the association may be specific to age group.