Determinants of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in house dust samples from four areas of the United States.

Determinants of levels of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) in dust in U.S. homes are not well characterized. We conducted a pilot study to evaluate the relationship between concentrations of PCDD/F in house dust and residential proximity to known sources, including industrial facilities and traffic. Samples from vacuum bag dust from homes of 40 residents of Detroit, Los Angeles, Seattle, or Iowa who participated in a population-based case-control study of non-Hodgkin lymphoma conducted in 1998-2000 were analyzed using high resolution gas chromatography/high resolution mass spectrometry for 7 PCDD and 10 PCDF congeners considered toxic by the U.S. Environmental Protection Agency (EPA). Locations of 10 types of PCDD/F-emitting facilities were obtained from the EPA; however only 4 types were located near study homes (non-hazardous waste cement kilns, coal-fired power plants, sewage sludge incinerators, and medical waste incinerators). Relationships between concentrations of each PCDD/F and proximity to industrial facilities, freight routes, and major roads were evaluated using separate multivariate regression models for each congener. The median (inter-quartile range [IQR]) toxic equivalence (TEQ) concentration of these congeners in the house dust was 20.3 pg/g (IQR=14.3, 32.7). Homes within 3 or 5 km of a cement kiln had 2 to 9-fold higher concentrations of 5 PCDD and 5 PCDF (p<0.1 in each model). Proximity to freight routes and major roads was associated with elevated concentrations of 1 PCDD and 8 PCDF. Higher concentrations of certain PCDD/F in homes near cement kilns, freight routes, and major roads suggest that these outdoor sources are contributing to indoor environmental exposures. Further study of the contribution of these sources and other facility types to total PCDD/F exposure in a larger number of homes is warranted.

Neural network analysis of employment history as a risk factor for prostate cancer.

BACKGROUND: Prostate cancer is the most common non-cutaneous malignancy in men. Its etiology likely involves environmental exposures and demographic factors. OBJECTIVE: Investigate the potential relationship between occupation history and prostate cancer risk in a population-based, case-control study (n=1365). METHODS: The variables: race, age group, smoking status, income, marital status, education and the first 15 years of employment history were examined by sequential odds ratio analysis then compared to a neural network consensus model. RESULTS: Both the sequential odds ratio method and the neural network consensus model identified a similar hypothetical case of greatest risk: a Black, married man, older than 60 years, with at best a high school diploma who made between $25,000-$65,000. The work history determined by odds ratio analysis consisted of 10 years in the chemical industry with 3 yrs in the processing plant. Neural network analysis showed a similar work history with 8 years in the chemical industry and 2 years in the processing plant. DISCUSSION: Neural network outcomes are similar to sequential odds ratio calculations. This work supported previous studies by finding well known demographic risk factors for prostate cancer including certain processing jobs and chemical related jobs.

Residential proximity to industrial facilities and risk of non-Hodgkin lymphoma.

Industrial pollution has been suspected as a cause of non-Hodgkin lymphoma (NHL), based on associations with chemical exposures in occupational studies. We conducted a case-control study of NHL in four SEER regions of the United States, in which residential locations of 864 cases and 684 controls during the 10 years before recruitment were used to characterize proximity to industrial facilities reporting chemical releases to the Environmental Protection Agency's Toxics Release Inventory (TRI). For each of 15 types of industry (by 2-digit SIC code), we evaluated the risk of NHL associated with having lived within 2 miles of a facility, the distance to the nearest facility (miles categories of < or =0.5, >0.5-1.0, >1.0-2.0, >2 [referent]), and the duration of residence within 2miles (years categories of 10, 1-9, 0 [referent]), using logistic regression. Increased risk of NHL was observed in relation to lumber and wood products facilities (SIC 24) for the shortest distance of residential proximity (< or =0.5 mile: odds ratio [OR]=2.2, 95% confidence interval [CI]: 0.4-11.8) or the longest duration (10 years: OR=1.9, 95% CI: 0.8-4.8); the association with lumber facilities was more apparent for diffuse large B-cell lymphoma (lived within 2 miles: OR=1.7, 95% CI: 1.0-3.0) than for follicular lymphoma (OR=1.1, 95% CI: 0.5-2.2). We also observed elevated ORs for the chemical (SIC 28, 10 years: OR=1.5, 95% CI: 1.1-2.0), petroleum (SIC 29, 10 years: OR=1.9, 95% CI: 1.0-3.6), rubber/miscellaneous plastics products (SIC 30, < or =0.5mile: OR=2.7, 95% CI: 1.0-7.4), and primary metal (SIC 33, lived within 2miles: OR=1.3, 95% CI: 1.0-1.6) industries; however, patterns of risk were inconsistent between distance and duration metrics. This study does not provide strong evidence that living near manufacturing industries increases NHL risk. However, future studies designed to include greater numbers of persons living near specific types of industries, along with fate-transport modeling of chemical releases, would be informative.

Degreasing and risk of non-Hodgkin lymphoma.

OBJECTIVE: To investigate the relationship between selected solvent-related workplace tasks (degreasing, painting, gluing, stripping paint, staining) and risk of non-Hodgkin lymphoma (NHL). METHODS: We analysed occupational data from a large population-based case-control study of NHL conducted in the USA. For participants reporting occupations with possible exposure to organic solvents, job-specific interview modules were administered to elicit in-depth information on solvent-related workplace tasks and other exposure-related factors (225 cases, 189 controls). Unconditional logistic regression models were fit to calculate odds ratios (ORs) and 95% CI for average frequency, maximal frequency and cumulative number of hours having performed each task. Individuals with jobs rated as unexposed to organic solvents in the workplace (180 cases, 213 controls) were used as a reference group. RESULTS: We observed an increased risk of NHL among subjects in the highest category of maximal degreasing frequency (>520 h/year: OR 2.1, 95% CI 0.9 to 4.9, trend test p = 0.02). We found similar associations for the highest levels of average frequency and, among men, cumulative number of hours. Other solvent-related tasks were not associated with NHL. CONCLUSION: Findings from this case-control analysis of solvent-related tasks suggest that frequent degreasing work may be associated with an elevated risk of NHL.

Occupation/industry and risk of non-Hodgkin's lymphoma in the United States.

AIMS: To identify occupations and industries associated with non-Hodgkin's lymphoma (NHL) in a large population-based, case-control study in the USA. METHODS: Cases (n = 1189) of histologically confirmed malignant NHL ages 20-74 were prospectively identified in four geographic areas covered by the National Cancer Institute SEER Program. Controls (n = 982) were selected from the general population by random digit dialling (<65 years of age) and from residents listed in Medicare files (65-74 years of age). Odds ratios and 95% confidence intervals for occupations and industries were calculated by unconditional logistic regression analyses, adjusting for age, gender, ethnicity and study centre. Further analyses stratified for gender and histological subtype were also performed. RESULTS: Risk of NHL was increased for a few occupations and industries. Several white collar occupations, with no obvious hazardous exposures, had elevated risks, including purchasing agents and buyers, religious workers, physical therapists and information clerks. Occupations with excesses that may have exposures of interest include launderers and ironers, service occupations, food/beverage preparation supervisors, hand packers and packagers, roofing and siding, leather and leather products, transportation by air, nursing and personal care facilities, and specialty outpatient clinics. Significantly decreased risks of NHL were found for a number of occupations and industries including post-secondary teachers and chemical and allied products. CONCLUSIONS: The results of this study suggest that several occupations and industries may alter the risk of NHL. Our results support previously reported increased risks among farmers, printers, medical professionals, electronic workers and leather workers. These findings should be evaluated further in larger studies that have the power to focus on specific exposures and histological subtypes of NHL.

Antibiotic use and risk of non-Hodgkin's lymphoma: a population-based case-control study.

Antibiotic use in 759 non-Hodgkin's lymphoma (NHL) patients and 589 controls was compared. Neither total antibiotic use (odds ratio=0.7, 95% confidence interval=0.5-1.2), nor antibiotic use by site, was associated with total NHL, or NHL subtypes. There were no trends with frequency or age at first use (P trend=0.23 and 0.26, respectively).

The effect of atopy, childhood crowding, and other immune-related factors on non-Hodgkin lymphoma risk.

OBJECTIVE: Since adult immune responsiveness is influenced by early childhood exposures, we examined the role of family size, history of atopic disease, and other childhood immune-related exposures in a multi-center case-control study of NHL. METHODS: Interviews were completed with 1,321 cases ascertained from population-based cancer registries in Seattle, Detroit, Los Angeles and Iowa, and with 1,057 frequency-matched controls, selected by random-digit dialing and from the Medicare files database. Multivariable logistic regression was used to estimate risk. RESULTS: A history of any allergy (excluding drug allergies), decreased risk of all NHL (Odds Ratio [OR] = 0.7, 95% Confidence Interval [CI] = 0.6-1.0), diffuse large B-cell lymphoma [DLBCL] (OR = 0.6, 95% CI = 0.4-0.9), and follicular NHL (OR = 0.7, 95 CI = 0.5, 1.0). A similar effect was observed for hay fever. A history of eczema was associated with an increased risk of follicular lymphoma (OR = 1.9, 95% CI = 1.1-3.4), but not DLBCL (OR = 1.1, 95% CI = 0.6-2.0). Asthma did not affect risk. Youngest compared to oldest siblings had a 90% increased risk of DLBCL (95% CI = 1.2-3.1; p for trend with increasing birth order = 0.006), but not follicular lymphoma (OR = 1.1, 95% CI = 0.6-1.8). CONCLUSIONS: We infer that some childhood and immune-related factors may alter NHL risk.

Radial bone density and breast cancer risk in white and African-American women.

A number of different models for assessing individual risk of breast cancer use known risk factors such as age, age at menarche, age at first live birth, previous breast biopsies, and family history. High bone mass in white women is also associated with an increased breast cancer risk; however, bone mass as a risk factor has not been studied in African-American women. We conducted a case-control study to evaluate bone mineral density as a risk factor for breast cancer in white and African-American women. We recruited 221 women with newly diagnosed breast cancer from a comprehensive breast cancer center at a large university hospital, and 197 control women who were frequency matched for ethnicity and age. Odds ratios were based on proximal and distal radial bone density measured by peripheral bone densitometry (Norland pDEXA) and expressed as a standardized "Z-score" (age and ethnicity specific). Logistic regression models were fitted controlling for body mass index, menopausal status, age, and HRT use (ever/never and duration). With proximal bone density Z-score included in the model as a continuous variable, a one-unit increase in radial shaft bone density increased the risk of breast cancer by 25% (p=0.02). When proximal bone density Z-score was analyzed as a dichotomous variable (< or = 0, > 0) the odds ratio was 1.98 (95% CI, 1.32 to 2.97); that is, having an above average proximal bone density (age-specific) doubles the risk of breast cancer. There were no significant interactions with, and no appreciable confounding effects by, other covariates. An above-average radial shaft Z-score is a significant risk factor for breast cancer in both white and African-American women. The present study extends the association between bone mass and breast cancer risk to African-Americans, and suggests another potential application for bone density testing.

Trends in the utilization of androgen-deprivation therapy for patients with prostate carcinoma suggest an effect on mortality.

BACKGROUND: After a surge in the incidence of prostate carcinoma in the early 1990s, diminishing rates of mortality became apparent in 1993. This decrease in mortality is unlikely to be explained entirely by treatment with curative intent alone following screen-detected cases, because the time frame between detection and mortality remains relatively brief. METHODS: This study used incidence and initial treatment data from the Detroit area SEER registry between 1973 and 1998 in addition to mortality data covering the Metropolitan Detroit area obtained from the Michigan Department of Community Health. Data for Caucasian and African-American men were analyzed. The use of androgen-deprivation therapy, which evolved during the study period, was evaluated in conjunction with mortality and incidence trend data for consideration of etiologic contributions. RESULTS: The incidence of prostate carcinoma, as noted previously in national data, increased sharply in 1988, peaking in 1992 in Southeast Michigan, whereas mortality rates began to decrease in approximately 1993, with a sustained decrease to the latest recorded data in 1998. These trends were identical in Caucasians and African Americans. A sharp increase in the use of androgen-deprivation therapy began in 1990. This use of androgen-deprivation therapy is high and sustained for patients with early-stage disease, increases for several years, and then diminishes for patients with regional disease. The use also diminished through the 1990s for patients with late-stage disease, paralleling the decrease in the incidence rate for late-stage disease. CONCLUSIONS: The pattern of androgen-deprivation therapy usage was consistent with that for hormonal monotherapy and adjuvant and neoadjuvant therapy. These findings suggest that androgen-deprivation therapy may contribute, along with advances in diagnostic techniques and curative therapy with radiation or surgery, toward decreasing prostate carcinoma mortality rates in Southeast Michigan.

Conditional median survival of patients with advanced carcinoma: surveillance, epidemiology, and end results data.

BACKGROUND: Conditional survival is clinically useful, particularly for patients with malignant disease who have a poor prognosis. However, there are no published data on the conditional median survival of patients with advanced carcinoma on a population basis. METHODS: Data on 217,573 patients with breast, colorectal, lung, or prostate carcinoma who were newly diagnosed with distant disease between 1973 and 1995 and who were followed through the end of 1997 were extracted from the Surveillance, Epidemiology, and End Results (SEER) data base of the National Cancer Institute. The Kaplan-Meier method was employed to estimate conditional median survival and 95% confidence intervals at 0-5 years after the initial diagnosis. RESULTS: The conditional median survival increased as time elapsed after the initial diagnosis. The increase was slowest and almost leveled off among patients with prostate carcinoma. The median survival of patients with breast carcinoma increased relatively linearly with time, i.e., 5-6 months per year. Conversely, there was a rapid increase in the conditional median survival according to the amount of time since diagnosis for patients with lung and colorectal carcinoma. The trend was most pronounced for patients with colorectal carcinoma. At 5 years after the initial diagnosis, the remaining median survival was longest for patients with colorectal carcinoma, almost 6 years (71.5 months), followed by patients with lung carcinoma (52.5 months), breast carcinoma (42.5 months), and prostate carcinoma (34.5 months). Although race was a correlate with initial survival, gender and age had more impact on late conditional survival. CONCLUSIONS: The conditional median survival provides useful and encouraging information for patients who survive with advanced disease and for healthcare professionals who treat these patients. However, the information should be used carefully, taking the limitations of these data into account.

Use of a template to improve documentation and coding.

BACKGROUND AND OBJECTIVES: Accurate assignment of evaluation and management (E&M) codes is a challenge for physicians. Having guidelines close at hand during patient visits might improve appropriateness and accuracy of E&M coding. We developed a template based on a clinical prediction rule for group A beta-hemolytic streptococcal (GABHS) pharyngitis to improve documentation and coding decisions. METHODS: Fifty office visits for sore throat were documented using templates and were compared with 50 sore throat visits that were documented using progress notes. We counted history and physical examination items and compared the level of service charged to the level of service supported by the note. RESULTS: Significantly more history of present illness and physical examination items were recorded on templates. Decisions related to treatment for patients with a low probability of GABHS were also improved by the templates. Templates had no effect on billing and coding errors. CONCLUSIONS: The template resulted in more-thorough documentation but had no effect on coding and billing errors relative to progress notes.

Impact of race in lung cancer: analysis of temporal trends from a surveillance, epidemiology, and end results database.

STUDY OBJECTIVES: We analyzed data from a community-based cancer database over a 26-year period in order to characterize clinicopathologic differences between black and white patients with lung cancer, and to identify relevant temporal trends in incidence and survival. DESIGN, SETTING, AND PATIENTS: Data on demographics, stage, histology, and survival were obtained on all black and white patients with primary bronchogenic carcinoma registered in the community-based metropolitan Detroit Surveillance, Epidemiology, and End Results database from 1973 to 1998. RESULTS: Of 48,318 eligible patients, 23% were black. Lung cancer incidence rates decreased for men of both races from 1985 to 1998, with a greater decline occurring in black men (p < 0.0001). Although incidence rates declined over time for men of both races < 50 years of age, this decrease was greater in white men, resulting in an increase in the racial differential in younger men. Temporal trends in incidence rates were similar for women of both races. The incidence of distant-stage disease was higher among blacks throughout the study period. The incidence of local-stage disease decreased for both races, though this decline was greater in blacks. A significant racial difference in 2-year and 5-year survival rates developed during the study period, due to a distinct lack of improvement in black patients. In a multivariate model, the relative risks of death for black patients, relative to white patients, were 1.24 (p < 0.0001) for local stage, 1.14 (p < 0.0001) for regional stage, and 1.03 (p = 0.045) for distant stage. CONCLUSION: Significant racial differences exist in the incidence and survival rates for lung cancer in metropolitan Detroit. Since 1973, several disturbing trends have developed, particularly with regard to the lack of improvement in overall survival in black patients. Further study is required to determine the factors responsible for these temporal trends.

Risk of injury in African American hospital workers.

Very few data exist that describe the risk of injury in African American health care workers, who are highly represented in health care occupations. The present study examined the risk for work-related injury in African American hospital workers. Hospital Occupational Health Service medical records and a hospital human resource database were used to compare risk of injury between African American and white workers after adjusting for gender, age, physical demand of the job, and total hours worked. Risk of work-related injury was 2.3 times higher in African Americans. This difference was not explained by the other independent variables. Differences in injury reporting, intra-job workload, psychosocial factors, and organizational factors are all potential explanations for racial disparity in occupational injury. More research is needed to clarify these findings.

Non-Hodgkin's lymphoma: an analysis of the Metropolitan Detroit SEER database.

We evaluated incidence and survival trends of non-Hodgkin's lymphoma (NHL) in a large population-based cancer registry. Data regarding demographics, histology, incidence, and survival were obtained on all patients with NHL registered in the Metropolitan Detroit Cancer Surveillance System, a participant in the Surveillance Epidemiology and End Results (SEER) Program of the National Cancer Institute. Incidence and survival trends from 1973 through 1995 were evaluated and stratified based on age at diagnosis, sex, race, and tumor grade. There were 11,978 patients diagnosed with NHL and recorded in the Metropolitan Detroit SEER registry from 1973 to 1995. The age-adjusted incidence rate increased from 8.6 to 15.8 per 100,000, leading to an overall increase in incidence of 83% and an average annual increase of 3.2% per year. Incidence increased significantly (p < 0.05) over time in all age groups except the youngest (ages 0-19) and in all demographic groups studied. Incidence was highest in white men and lowest in black women. The incidence of both low-grade and intermediate/high-grade NHL increased significantly for each age group (p < 0.05) except the youngest (ages 0-19). In the oldest patients (70+ years), the incidence of intermediate/high-grade NHL was almost double that of low-grade NHL. Five-year relative survival increased from 64% (1973-1983) to 68% (1984-1991) for patients with low-grade NHL and from 40% to 44% for those with intermediate/high-grade NHL. The increase in relative survival was only seen in whites, however, with 5-year relative survival in blacks decreased from 53% (1973-1983) to 45% (1984-1991). In metropolitan Detroit, the current NHL epidemic affects all age groups except the very young (ages 0-19), both sexes, and both whites and blacks and is due to increases in the incidence of both low-grade and intermediate/high-grade NHL. Five-year survival rates have increased for whites but not for blacks.

Early deaths in childhood cancer.

BACKGROUND: Deaths prior to or shortly after the diagnosis of childhood cancer may reflect inadequacies in detection and appropriate referral for care. This study was performed to determine the extent of and factors associated with early death in childhood cancer. PROCEDURE: Patients with of primary cancer, aged <20 years at diagnosis, were identified from the SEER data (n = 23,470) from 1973 to 1995. Early deaths were defined as cases identified by 1) death certificate, 2) autopsy report, or 3) death within 1 month of initial diagnoses (n = 481). Cause of death was determined by ICD-8 and -9 codes. Age at diagnosis, year of diagnosis, morphology, site of disease, race, and gender were evaluated for association with early death. RESULTS: Age <1 year at diagnosis (6.2% early deaths), being diagnosed earlier in the observation period, and a diagnosis of a brain tumor, neuroblastoma, leukemia, or liver tumor were associated with increased early death. Gender and race were not associated with early death. Among the cases for whom the malignant diagnosis was made at the time of death (n = 119), the cause of death was nonmalignant for 36. For 22 of these cases the malignancy was an incidental finding and appeared not to contribute directly to the cause of death. Among these patients, 11 had neuroblastoma, 9 being <1 year of age. CONCLUSIONS: A decrease in the proportion of early deaths associated with childhood cancer has occurred during the past 2 decades. This decrease may reflect earlier diagnosis or improved imaging capabilities, surgical techniques, medical therapy, and supportive care. Awareness among pediatricians, general practitioners, and emergency physicians is warranted, with a focus on high-risk groups for early detection among childhood cancer patients.

Paternal military service and risk for childhood leukemia in offspring.

To assess the association between paternal military service and risk for childhood leukemia, the authors analyzed data from three case-control studies conducted by the Children's Cancer Group from 1983 to 1993. A total of 605 acute myeloid leukemia (AML, age < or = 18 years) cases, 2,117 acute lymphoblastic leukemia (ALL, age < or = 14 years) cases, and 3,155 individually matched controls were included in these studies. Paternal military history and other exposure data were obtained in 2,343 matched case-control sets, including 1,805 ALL and 528 AML cases. Paternal general military service was not associated with the leukemia risk. A small, but significant, increase in the risk for AML was seen, however, among offspring of veterans who had served in Vietnam or Cambodia (odds ratio (OR) = 1.7; 95% confidence interval (CI): 1.0, 2.9), after adjustment for paternal education, race, income, smoking, X-ray exposure, and marijuana use. The risk was predominantly present in children diagnosed before the age of 2 (OR = 4.6; 95% CI: 1.3, 16.1), although there were inconsistencies in the risks associated with length of time served and interval between service and diagnosis of leukemia. Military service in Vietnam or Cambodia was unrelated to the risk for ALL. The etiologic importance, if any, of these observations has yet to be determined.

Consistency of occupational exposure history from pattern and model makers.

This study investigates the consistency of occupational histories reported by the same men in 1985 and again in 1988. Detroit-area pattern and model makers participating in a colorectal cancer screening program that was offered at 3-year intervals completed a career length occupational exposure questionnaire at each screening. Analysis of the data from the 243 men who participated in both screening programs provided the opportunity to examine the consistency with which these workers reported the extent of their exposure to 13 substances commonly found in their work environment. Workers were asked to provide a work history, and for each different pattern or model maker job they had held, to estimate the percentage of time they were exposed to the 13 substances. The data indicated that over the 3-year study period, pattern and model makers were highly consistent in reporting whether or not they were exposed to the 13 substances. In addition, their first estimates of the percentage of time they were exposed to each substance were within 10% of their second estimates more than 70% of the time. This concordance was somewhat diminished after excluding those who reported no exposure. These findings suggest that skilled tradesman can provide occupational exposure information that is likely to be useful for physicians in considering an occupational cause for a presenting health concern.

Patterns of infection and day care utilization and risk of childhood acute lymphoblastic leukaemia.

To investigate if decreased exposure to common childhood infections is associated with risk of childhood acute lymphoblastic leukaemia (ALL) we conducted a case-control study of 1842 newly diagnosed and immunophenotypically defined cases of ALL under age 15, and 1986 matched controls in the US. Data regarding day care, sibship size and common childhood infections were obtained through parental interviews. Data were analysed stratified by leukaemia lineage and separately for 'common' childhood ALL (age 2-5 years, CD19, CD10-positive). Neither attendance at day care nor time at day care was associated with risk of ALL overall or 'common' ALL. Ear infections during infancy were less common among cases, with odds ratios of 0.86, 0.83, 0.71 and 0.69 for 1, 2-4, 5+ episodes, and continuous infections respectively (trend P = 0.026). No effect of sibship size or birth interval was seen. With one exception (ear infections), these data do not support the hypothesis that a decrease in the occurrence of common childhood infection increases risk of ALL.

Seasonal variations in the diagnosis of childhood cancer in the United States.

Seasonal trends in month of diagnosis have been reported for childhood acute lymphoblastic leukaemia (ALL) and non-Hodgkin's lymphoma (NHL). This seasonal variation has been suggested to represent an underlying viral aetiology for these malignancies. Some studies have shown the highest frequency of diagnoses in the summer months, although this has been inconsistent. Data from the Children's Cancer Group and the Pediatric Oncology Group were analysed for seasonal incidence patterns. A total of 20,949 incident cancer cases diagnosed in the USA from 1 January 1989 through 31 December 1991 were available for analyses. Diagnosis-specific malignancies available for evaluation included ALL, acute myeloid leukaemia (AML), Hodgkin's disease, NHL, rhabdomyosarcoma, neuroblastoma, retinoblastoma, osteosarcoma, Wilms' tumour, retinoblastoma, Ewings' sarcoma, central nervous system (CNS) tumours and hepatoblastoma. Overall, there was no statistically significant seasonal variation in the month of diagnosis for all childhood cancers combined. For diagnosis-specific malignancies, there was a statistically significant seasonal variation for ALL (P = 0.01; peak in summer), rhabdomyosarcoma (P = 0.03; spring/summer) and hepatoblastoma (P = 0.01; summer); there was no seasonal variation in the diagnosis of NHL. When cases were restricted to latitudes greater than 40 degrees ('north'), seasonal patterns were apparent only for ALL and hepatoblastoma. Notably, 33% of hepatoblastoma cases were diagnosed in the summer months. In contrast, for latitudes less than 40 degrees ('south'), only CNS tumours demonstrated a seasonal pattern (P = 0.002; winter). Although these data provide modest support for a summer peak in the diagnosis of childhood ALL, any underlying biological mechanisms that account for these seasonal patterns are likely complex and in need of more definitive studies.