Diagnostic radiography and adult acute myeloid leukaemia: an interview and medical chart review study.

BACKGROUND: Aetiology of acute myeloid leukaemia (AML) is not well understood, perhaps because of its distinct subtypes. High-dose ionising radiation is a known risk factor, but less is known about risk from low-dose exposure such as from diagnostic radiography. METHODS: Subjects were 412 matched case-control pairs. Ten-year subject histories of diagnostic radiography were based on interview and medical records. RESULTS: There was no convincing association between AML risk and ionising radiation exposure from diagnostic imaging procedures, either for AML overall or for any AML subtype. CONCLUSION: The association between diagnostic radiography and AML risk remains uncertain.

A pooled analysis of extremely low-frequency magnetic fields and childhood brain tumors.

Pooled analyses may provide etiologic insight about associations between exposure and disease. In contrast to childhood leukemia, no pooled analyses of childhood brain tumors and exposure to extremely low-frequency magnetic fields (ELF-MFs) have been conducted. The authors carried out a pooled analysis based on primary data (1960-2001) from 10 studies of ELF-MF exposure and childhood brain tumors to assess whether the combined results, adjusted for potential confounding, indicated an association. The odds ratios for childhood brain tumors in ELF-MF exposure categories of 0.1-<0.2 µT, 0.2-<0.4 µT, and ≥0.4 µT were 0.95 (95% confidence interval: 0.65, 1.41), 0.70 (95% CI: 0.40, 1.22), and 1.14 (95% CI: 0.61, 2.13), respectively, in comparison with exposure of <0.1 µT. Other analyses employing alternate cutpoints, further adjustment for confounders, exclusion of particular studies, stratification by type of measurement or type of residence, and a nonparametric estimate of the exposure-response relation did not reveal consistent evidence of increased childhood brain tumor risk associated with ELF-MF exposure. These results provide little evidence for an association between ELF-MF exposure and childhood brain tumors.

Effect of tuberculosis on the survival of women infected with human immunodeficiency virus.

Evidence regarding the effect of tuberculosis (TB) disease on progression of human immunodeficiency virus (HIV) disease is inconclusive. The authors estimated the effect of time-varying incident TB on time to acquired immunodeficiency syndrome (AIDS)-related mortality using a joint marginal structural Cox model. Between 1995 and 2002, 1,412 HIV type 1 (HIV-1)-infected women enrolled in the Women's Interagency HIV Study were followed for a median of 6 years. Twenty-nine women incurred incident TB, and 222 died of AIDS-related causes. Accounting for age, CD4 cell count, HIV-1 RNA level, serum albumin level, and non-TB AIDS at study entry, as well as for time-varying CD4 cell count, CD4 cell count nadir, HIV-1 RNA level, peak HIV-1 RNA level, serum albumin level, HIV-related symptoms, non-TB AIDS, anti-Pneumocystis jiroveci prophylaxis, antiretroviral therapy, and household income, the hazard ratio for AIDS-related death comparing time after incident TB with time before incident TB was 4.0 (95% confidence interval (CI): 1.2, 14). The effect of incident TB on mortality was similar among highly active antiretroviral therapy (HAART)-exposed women (hazard ratio = 4.3, 95% CI: 0.9, 22) and non-HAART-exposed women (hazard ratio = 3.9, 95% CI: 0.9, 17; interaction p = 0.91). Although results were imprecise because few women incurred TB, irrespective of HAART exposure, incident TB increases the hazard of AIDS-related death among HIV-infected women.

Beauty product-related exposures and childhood brain tumors in seven countries: results from the SEARCH International Brain Tumor Study.

Data from 1218 cases of childhood brain tumors (CBT) diagnosed between 1976 and 1994 and 2223 matched controls from the general population were included in an analysis of maternal beauty product exposure and beauty-related employment in 9 centers in 7 countries. A 50% increased odds ratio (OR) [95% confidence interval (CI) = 1.0-2.1] for CBT was observed among children of mothers who were exposed via personal use of and/or possible ambient contact with beauty products during the 5 years preceding the index child's birth compared with children of mothers never exposed to beauty products during this time period. Overall maternal personal use of hair-coloring agents in the month before or during the pregnancy of the index child's birth was not associated with CBT (OR = 1.0, CI = 0.83-1.3) or with astroglial (OR = 1.1, CI = 0.85-1.4), PNET (OR = 1.0, CI = 0.71-1.5) and other glial subtypes (OR = 1.0, CI = 0.62-1.0). Similarly, no statistically increased ORs or discernable pattern of risk estimates were observed for period of use or for number of applications per year for maternal personal use of hair-coloring agents overall or by histologic type. Among children born on or after 1980, increased ORs for CBT were associated with maternal non-work-related exposure to any beauty products (OR = 2.6, CI = 1.2-5.9), hair-dyes (OR = 11, CI = 1.2-90), and hair sprays (OR = 3.4, CI = 1.0-11). No overall increased OR for CBT was observed among children of mothers employed in beauty-related jobs during the 5 years preceding the index child's birth compared with those who reported no beauty-related employment. In general, other specific beauty product-related exposures were not associated with increased ORs for CBT. Data from our study provide little evidence of an increased risk for CBT with mothers' exposures to beauty products.

Incidence of acute lymphoblastic leukaemia in white and coloured children in the Western Cape.

UNLABELLED: Objectives. To record the age-specific incidence rate (ASIR) for diagnosed acute lymphoblastic leukaemia (ALL) in coloured and white children aged 0 - 12 years in the Western Cape (WC). DESIGN: A retrospective population-based study using the 1991 population census to calculate the mean annual childhood population and the ASIR for ALL in the 0 - 4, 5 - 9 and 10 - 12-year age groups in rural and Cape Town metropolitan areas for the period 1983 - 1999. Odds ratios were calculated using EpiInfo 2000. SETTING: Registry records of the paediatric cancer units at Tygerberg and Red Cross War Memorial Children's hospitals where all children with ALL in the WC were initially treated. SUBJECTS: All white and coloured children aged 0 - 12 years diagnosed as having ALL from 1983 - 1999. OUTCOME MEASURES: The ASIR by age and ethnic group in rural and metropolitan patients in the WC. RESULTS: The estimated annual childhood population in 1991 was 709 151 with 80.4% coloured and 19.6% white children, of whom 60% were resident in the Cape Town metropolitan area and 40% in the rural area of the WC. Of 246 children with ALL diagnosed in the period 1983 - 1999, 144 were male and 102 female. The ASIR in coloured children aged 0 - 4 years was 17.1/10(6) in the rural and 30.5/10(6) in the metropolitan area, compared with 55.7/10(6) and 56.2/10(6) respectively in white children. In the 5 - 9-year age group the ASIR in coloured children was 10.0/10(6) in the rural and 16.6/10(6) in the metropolitan area compared with 27.6/10(6) and 26.7/10(6) respectively in white children. The 10 - 12-year age group had comparable incidence rates in both populations and geographical areas. Only one case occurred within a 20 km radius of the Koeberg nuclear reactor. CONCLUSIONS: White children have an ASIR for ALL comparable to rates of diagnosis in the USA, while only half as many coloured children aged 0 - 9 years were diagnosed in both the rural and metropolitan areas. This contrast may indicate significant underdiagnosis of ALL in coloured children over the period in question. The change in health policy since 1994, which has improved access to primary health care, may improve the rate of diagnosis among coloured and black children.

Parental exposure to polycyclic aromatic hydrocarbons and the risk of childhood brain tumors: The SEARCH International Childhood Brain Tumor Study.

Experimental evidence suggests that parental exposure to polycyclic aromatic hydrocarbons (PAH), which occurs primarily through tobacco smoke, occupational exposure, and air pollution, could increase the risk of cancer during childhood. Population-based case-control studies carried out in seven countries as part of the SEARCH Program compared data for 1,218 cases of childhood brain tumors and 2,223 controls (1976-1994). Parental occupational exposure to PAH during the 5-year period before birth was estimated with a job exposure matrix. Risk estimates were adjusted for child's age, sex, and study center. Paternal preconceptional occupational exposure to PAH was associated with increased risks of all childhood brain tumors (odds ratio (OR) = 1.3, 95% confidence interval: 1.1, 1.6) and astroglial tumors (OR = 1.4, 95% confidence interval: 1.1, 1.7). However, there was no trend of increasing risk with predicted level of exposure. Paternal smoking alone (OR = 1.4) was also associated with the risk of astroglial tumors in comparison with nonsmoking, non-occupationally-exposed fathers. Risks for paternal occupational exposure were higher, with (OR = 1.6) or without (OR = 1.7) smoking. Maternal occupational exposure to PAH before conception or during pregnancy was rare, and this exposure was not associated with any type of childhood brain tumor. This large study supports the hypothesis that paternal preconceptional exposure to PAH increases the risk of brain tumors in humans.

Contacts with animals and humans as risk factors for adult brain tumours. An international case-control study.

While numerous studies have addressed the possible role of farming and related exposures as risk factors for brain tumours in adults, few of them have examined the potential effect of exposure to farm animals or pets. In an international multicentre case-control study, we investigated whether residence on a farm, contact with animals, or working in occupations with a high degree of potential contact with animals or humans were associated with brain tumours. Using a common questionnaire, 1177 cases of glioma, 330 with meningioma and 2478 controls from eight centres were interviewed about the exposures and, in particular, about their contacts with nine species of animals: dairy cattle, beef cattle, pigs, horses, sheep, goats, poultry, dogs and cats. Living or working on a farm was not a risk factor, for either glioma or meningioma. Except in some centres, there was no relationship between having contacts with farm animals or pets and the risk of brain tumour, for either type of tumour or either sex. In relation to seven industrial groups involving frequent human and/or animal contacts, no association was apparent for either glioma or meningioma. In relation to 25 occupational groups with potential frequent contact with humans and/or animals, for glioma there was a reduced risk for biological technicians (Odds Ratio (OR)/=0, P=0.01), and general farm workers (OR=0.66, 95% Confidence Interval (CI): 0.5-0.9). For meningioma, there was an increased risk for cooks (OR=2.0; CI: 1.2-3.4). With some exceptions, these results indicate no association between either the type of brain tumour and contacts with animals, or with occupations that include a high level of contact with animals or a high level of contact with humans.

Parental occupations and childhood brain tumors: results of an international case-control study.

OBJECTIVE: To evaluate the role of parental occupations in the etiology of childhood brain tumors (CBT). METHODS: Population-based case-control studies were conducted concurrently in seven countries under the coordination of the International Agency for Research on Cancer, gathering 1,218 cases and 2,223 controls. We report here the findings related to parental occupations during the 5-year period before the child's birth. Risk estimates related to a number of paternal and maternal occupations were obtained by unconditional logistic regression adjusted for age, sex, year of birth, and center, for all types of CBT combined and for the subgroups of astroglial, primitive neuroectodermal tumors (PNET), and other glial tumors. RESULTS: An increased risk in relation with agricultural work was seen for all CBT combined and for other glial tumors. Increased risks for all tumors and PNET were seen for paternal occupation as an electrician; the same pattern held for maternal occupation when children under 5 were selected. Paternal occupation as a driver or mechanic, and maternal work in an environment related to motor-vehicles were associated with an increased risk for all CBT and astroglial tumors. More case mothers compared to control mothers were employed in the textile industry. CONCLUSION: Our study reinforces previous findings relative to the role of parental work in agriculture, electricity, or motor-vehicle related occupations and maternal work in the textile industry. It does not confirm previous associations with work environments including aerospace, the chemical industry, or the food industry, or with maternal occupation as a hairdresser, a nurse, or a sewing machinist, and paternal occupation as a welder.

A pooled analysis of case-control studies of thyroid cancer. VI. Fish and shellfish consumption.

OBJECTIVE: To better understand the role of fish and shellfish on thyroid cancer risk, we systematically re-analyzed the original data from 13 case-control studies conducted in the US, Japan, China, and Europe. METHODS: A total of 2497 cases (2023 women, 474 men) and 4337 controls (3268 women, 1069 men) were considered. Odds ratio (OR) and corresponding 95% confidence interval (CI) were estimated for each study by logistic regression models, conditioned on age and sex, and adjusted for history of goiter, thyroid nodules or adenomas, and radiation. Combined ORs were computed as the weighted average of the estimates from each study. RESULTS: The ORs for the highest level of total fish consumption (three or more times per week) as compared to the lowest one (less than once per week) was above unity in Hawaii, Connecticut, Japan, Norway, Tromsø, and Vaud. Conversely, the ORs for the studies in Los Angeles. Shanghai, southeastern Sweden, Uppsala, northern Sweden, northern Italy, and Athens were below one. The pattern of risk for salt water fish and shellfish was not substantially different from that of total fish. Fish was not associated with thyroid cancer risk in all studies combined (OR = 0.99, 95% CI 0.85-1.2 for moderate, and OR=0.88, 95% CI 0.71-1.1 for high total fish consumption), but there was a suggestion of a protective effect in endemic goiter areas (OR = 0.65, 95% CI 0.48-0.88). CONCLUSION: This combined analysis indicates that relatively elevated fish consumption does not appreciably increase thyroid cancer risk, and may have a favorable influence in areas where iodine deficiency is, or was, common.

Residential water source and the risk of childhood brain tumors.

Gestation may represent a window of susceptibility to transplacental effects of environmental exposures, including chemicals in water. The N-nitroso compounds (NNC), a class of chemicals with demonstrated neurocarcinogenic potential, include substances detected in drinking water. We used data from a study of possible risk factors for childhood brain tumors (CBT) to investigate the association of source of residential drinking water during pregnancy and CBT occurrence among offspring. In addition, dipstick measurements were made of nitrates and nitrites in tap water for the subset of women living in the same home they had lived in during their pregnancies. Population-based CBT cases (n = 540) and controls (n = 801) were identified in three regions including Los Angeles County, and the San Francisco Bay Area of California, and the Seattle-Puget Sound area of western Washington state. Overall, we observed no increased risk of CBT in offspring associated with wells as the source of residential water. However, an increased risk of CBT [odds ratio (OR) = 2.6; 95% confidence interval (CI), = 1.3-5.2] was observed in western Washington among offspring of women who relied exclusively on well water, and a decreased risk of CBT (OR = 0.2; 95% CI, 0.1-0.8) was observed in Los Angeles County. Among the small subset of subjects for whom dipstick measurements of tap water were available, the risk of CBT associated with the presence of either measurable nitrite and/or nitrate was 1.1 (95% CI, 0.7-2.0). Given the crude measurement method employed and because measurements often were obtained years after these pregnancies occurred, the relevance of the dipstick findings is unclear. The lack of consistency in our findings related to residential water source does not support the hypothesis of increased risk related to consumption of well water; however, regional differences in well water content may exist, and the increased risk observed in western Washington deserves further evaluation.

Maternal cured meat consumption during pregnancy and risk of paediatric brain tumour in offspring: potentially harmful levels of intake.

OBJECTIVE: To describe the relationship between specific levels of nitrite intake from cured meat consumption during pregnancy and the relative risk of paediatric brain tumours in the offspring. DESIGN: Exposure data were previously collected for a population-based case-control study of paediatric brain tumours; data on nitrite content were obtained by a comprehensive literature review of surveys of residual nitrite content in cured meats published in the USA and Canada. The level of nitrite intake for each mother was predicted by year of pregnancy based on survey results. Dose-response was evaluated both categorically and continuously using polynomial and quadratic spline regression. SETTING: The US west coast: Los Angeles County, the San Francisco-Oakland Bay Area and the Seattle-Puget Sound area. SUBJECTS: There were 540 cases diagnosed between 1984 and 1990 at ages varying from 0 to 19 years, and 801 controls frequency-matched by geographic area, age and birth year. RESULTS: In general, survey results suggest a trend of decreasing nitrite levels in cured meats over time. We observed a moderate increase in brain tumour risk in the offspring of mothers with relatively low levels of nitrite consumption from cured meats during pregnancy, and a two- to three-fold risk increase in offspring of mothers who consumed 3 mg day-1 nitrite from cured meats (about 125 g day-1 of cured meat consumption throughout the pregnancy). CONCLUSIONS: A substantial risk of paediatric brain tumour appears to be associated with relatively high levels of maternal cured meat consumption during pregnancy. A more scientifically valid approach than a literature review to estimate nitrite intake from cured meats and data from a large group of highly exposed subjects would be useful in determining potentially harmful levels.

Reliability of demographic, smoking and occupational data provided by mothers vs. fathers in a childhood cancer study.

A large case-control study of children was used to test mothers' reporting of information on fathers' background, lifestyle and occupational factors. For a subset (104) of 1341 enrolled families, both parents were interviewed about fathers' characteristics. Reliability of reporting was determined for fathers' race, education, smoking status, non-recent job history and use of occupational agents. The ability of mothers to report fathers' race, education and smoking status was high (kappa > 0.70). Mothers were generally able to report jobs held by the fathers in the 5 years preceding the birth of the child, but reliability was higher for jobs held for longer (kappa typically above 0.70), rather than shorter periods (kappa above 0.40). The finding that mothers' reporting on fathers' background, lifestyle and non-recent job history was reliable is encouraging, because many studies on childhood health rely exclusively on information from interviews with mothers. However, mothers were not reliably able to describe exposure to specific occupational agents.

A pooled analysis of thyroid cancer studies. V. Anthropometric factors.

OBJECTIVE: To assess the relation between anthropometric factors and thyroid cancer risk in a pooled analysis of individual data from 12 case-control studies conducted in the US, Japan, China and Europe. METHODS: 2056 female and 417 male cases, 3358 female and 965 male controls were considered. Odds ratios (OR) were derived from logistic regression, conditioning on age, A-bomb exposure (Japan) and study, and adjusting for radiotherapy. RESULTS: Compared to the lowest tertile of height, the pooled OR was 1.2 for females for the highest one, and 1.5 for males, and trends in risk were significant. With reference to weight at diagnosis, the OR for females was 1.2 for the highest tertile, and the trend in risk was significant, whereas no association was observed in males. Body mass index (BMI) at diagnosis was directly related to thyroid cancer risk in females (OR = 1.2 for the highest tertile), but not in males. No consistent pattern of risk emerged with BMI during the late teens. Most of the associations were observed both for papillary and follicular cancers, and in all age groups. However, significant heterogeneity was observed across studies. CONCLUSIONS: Height and weight at diagnosis are moderately related to thyroid cancer risk.

Descriptive epidemiology of thyroid cancer in Los Angeles County, 1972-1995.

OBJECTIVE: To examine the descriptive epidemiologic features of incident thyroid cancers diagnosed among Los Angeles County residents between 1972 and 1995. METHODS: The Los Angeles County/University of Southern California Cancer Surveillance Program (CSP) collected data on 8820 newly diagnosed thyroid cancer of cases occurring in Los Angeles County. Average annual age-adjusted incidence rates were calculated to study the epidemiology of each of the major histologic types of thyroid carcinoma. RESULTS: For all races combined, the age-adjusted incidence rates were 2.5 per 100,000 males and 6.0 per 100,000 females. Differences in incidence by ethnicity were particularly striking, with Filipinos demonstrating the highest incidence rates (4.44 per 100,000 males, 11.3 per 100,000 females). Over the 23-year period, thyroid cancer incidence rates increased 1.5% per year for males and 1% per year for females. By histology, papillary carcinoma rates increased over time and follicular carcinoma rates decreased. Non-Spanish surnamed white men employed in certain white-collar occupations and radiologic technicians were at greater risk of thyroid cancer. CONCLUSIONS: Additional research on the epidemiologic risk factors for thyroid cancer, particularly for gender and ethnicity, is needed to explain the marked elevated incidence rates among females and the Filipino population in Los Angeles County.

Reproductive and hormonal risk factors for thyroid cancer in Los Angeles County females.

We conducted an individually matched case-control study (292 pairs) of female thyroid cancer patients to examine the role of reproductive history and exogenous hormones in this disease. Radiation treatment to the head or neck [28 cases and 2 controls exposed; odds ratio (OR), 14.0; 95% confidence interval (CI), 3.5-121.3] and certain benign thyroid diseases (including adolescent thyroid enlargement, goiter, and nodules or tumors) were strongly associated with thyroid cancer. Irregular menstruation increased risk (OR, 1.8; 95% CI, 0.9-3.7). Age at menarche and pregnancy history were not related to disease. Women with natural menopause and hysterectomized women without oophorectomy had no increase in risk, but disease risk was elevated in women with bilateral oophorectomy (OR, 6.5; 95% CI, 1.1-38.1). In general, use of oral contraceptives and other exogenous estrogens was not associated with thyroid cancer. However, risk increased with number of pregnancies in women using lactation suppressants (P = 0.03) and decreased with duration of breastfeeding (P = 0.04). These data provide only limited support for the hypothesis that reproductive and hormonal exposures are responsible for the marked excess of thyroid cancer risk in adult females.

SEARCH international case-control study of childhood brain tumours: role of index pregnancy and birth, and mother's reproductive history.

A series of co-ordinated population-based case-control studies of childhood brain tumours (CBT) was undertaken under the auspices of the Surveillance of Environmental Aspects Related to Cancer in Humans (SEARCH) programme of the International Agency for Research on Cancer (IARC) to evaluate, inter alia, the risk in relation to characteristics of the index pregnancy and birth, and maternal reproductive history. Subjects comprised 1218 cases aged 0-19 years and 2223 controls. Risk estimates were calculated by unconditional logistic regression, adjusted for age, sex, centre and mother's years of schooling, for all types of CBT combined as well as for four groups defined by histopathology (astrologlial tumours, primitive neuroectodermal tumours of the brain, 'other glial' tumours and 'other histological types') and for five age groups (0-1, 0-4, 5-9, 10-14, 15-19 years). Use of anaesthetic 'gas' was associated with an increased risk of CBT (OR = 1.5, 95% CI [1.1, 2.0]), apparent in children aged 0-4 years (OR = 2.4, 95% CI [1.4, 4.1]) and for astroglial tumours (OR = 1.6, 95% CI [1.1, 2.2]) with non-significantly increased relative risks for each of the other histological groups. However, not all centre-specific relative risks were elevated. No other aspect of the index pregnancy, delivery and early neonatal period or of the mother's previous reproductive history was associated with risk for CBT.