Dietary acrylamide and the risk of pancreatic cancer in the International Pancreatic Cancer Case-Control Consortium (PanC4)

Background

Occupational exposure to acrylamide was associated with excess mortality from pancreatic cancer, though in the absence of dose-risk relationship. Few epidemiological studies have examined the association between acrylamide from diet and pancreatic cancer risk.

Patients and methods

We considered this issue in a combined set of 1975 cases of pancreatic cancer and 4239 controls enrolled in six studies of the Pancreatic Cancer Case-Control Consortium (PanC4). We calculated pooled odds ratios (ORs) and their 95% confidence intervals (CI) by estimating study-specific ORs through multivariate unconditional logistic regression models and pooling the obtained estimates using random-effects models.

Results

Compared with the lowest level of estimated dietary acrylamide intake, the pooled ORs were 0.97 (95% CI, 0.79-1.19) for the second, 0.91 (95% CI, 0.71-1.16) for the third, and 0.92 (95% CI, 0.66-1.28) for the fourth (highest) quartile of intake. For an increase of 10 µg/day of acrylamide intake, the pooled OR was 0.96 (95% CI, 0.87-1.06), with heterogeneity between estimates (I2 = 67%). Results were similar across various subgroups, and were confirmed when using a one-stage modelling approach.

Conclusions

This PanC4 pooled-analysis found no association between dietary acrylamide and pancreatic cancer.

Diabetes, antidiabetic medications, and pancreatic cancer risk: an analysis from the International Pancreatic Cancer Case-Control Consortium

BACKGROUND

Type 2 diabetes mellitus has been associated with an excess risk of pancreatic cancer, but the magnitude of the risk and the time-risk relationship are unclear, and there is limited information on the role of antidiabetic medications.

PATIENTS AND METHODS

We analyzed individual-level data from 15 case-control studies within the Pancreatic Cancer Case-Control Consortium, including 8305 cases and 13 987 controls. Pooled odds ratios (ORs) were estimated from multiple logistic regression models, adjusted for relevant covariates.

RESULTS

Overall, 1155 (15%) cases and 1087 (8%) controls reported a diagnosis of diabetes 2 or more years before cancer diagnosis (or interview, for controls), corresponding to an OR of 1.90 (95% confidence interval, CI, 1.72-2.09). Consistent risk estimates were observed across strata of selected covariates, including body mass index and tobacco smoking. Pancreatic cancer risk decreased with duration of diabetes, but a significant excess risk was still evident 20 or more years after diabetes diagnosis (OR 1.30, 95% CI 1.03-1.63). Among diabetics, long duration of oral antidiabetic use was associated with a decreased pancreatic cancer risk (OR 0.31, 95% CI 0.14-0.69, for ≥15 years). Conversely, insulin use was associated with a pancreatic cancer risk in the short term (OR 5.60, 95% CI 3.75-8.35, for <5 years), but not for longer duration of use (OR 0.95, 95% CI 0.53-1.70, for ≥15 years).

CONCLUSION

This study provides the most definitive quantification to date of an excess risk of pancreatic cancer among diabetics. It also shows that a 30% excess risk persists for more than two decades after diabetes diagnosis, thus supporting a causal role of diabetes in pancreatic cancer. Oral antidiabetics may decrease the risk of pancreatic cancer, whereas insulin showed an inconsistent duration-risk relationship.

Ulcer, gastric surgery and pancreatic cancer risk: an analysis from the International Pancreatic Cancer Case-Control Consortium (PanC4)

BACKGROUND

Peptic ulcer and its treatments have been associated to pancreatic cancer risk, although the evidence is inconsistent.

METHODS

We pooled 10 case-control studies within the Pancreatic Cancer Case-control Consortium (PanC4), including 4717 pancreatic cancer cases and 9374 controls, and estimated summary odds ratios (OR) using multivariable logistic regression models.

RESULTS

The OR for pancreatic cancer was 1.10 [95% confidence interval (CI) 0.98-1.23] for history of ulcer (OR = 1.08 for gastric and 0.97 for duodenal ulcer). The association was stronger for a diagnosis within 2 years before cancer diagnosis (OR = 2.43 for peptic, 1.75 for gastric, and 1.98 for duodenal ulcer). The OR was 1.53 (95% CI 1.15-2.03) for history of gastrectomy; however, the excess risk was limited to a gastrectomy within 2 years before cancer diagnosis (OR = 6.18, 95% CI 1.82-20.96), while no significant increased risk was observed for longer time since gastrectomy. No associations were observed for pharmacological treatments for ulcer, such as antacids, H2-receptor antagonists, or proton-pump inhibitors.

CONCLUSIONS

This uniquely large collaborative study does not support the hypothesis that peptic ulcer and its treatment materially affect pancreatic cancer risk. The increased risk for short-term history of ulcer and gastrectomy suggests that any such association is due to increased cancer surveillance.

Postmenopausal hormone therapy and non-Hodgkin lymphoma: a pooled analysis of InterLymph case-control studies

BACKGROUND

Non-Hodgkin lymphoma (NHL) subtypes, diffuse large B-cell (DLBCL) and follicular lymphoma (FL) have different sex ratios and are diagnosed at ages over 60 years; DLBCL is more common in men and diagnosed at older ages than FL, which occurs more among women. This analysis of postmenopausal women examines the relationship between postmenopausal hormone therapy and NHL.

DESIGN

Self-reported use of postmenopausal hormone therapy from 2094 postmenopausal women with NHL and 2731 without were pooled across nine case-control studies (1983-2005) from North America, Europe and Japan. Study-specific odds ratios (OR) and 95% confidence intervals (CI) estimated using logistic regression were pooled using random-effects meta-analyses.

RESULTS

Postmenopausal women who used hormone therapy were at decreased risk of NHL (pooled OR = 0.79, 95% CI 0.69-0.90). Risks were reduced when the age of starting was 50 years or older. There was no clear trend with number of years of use. Current users were at decreased risk while those stopping over 2 years before diagnosis were not. Having a hysterectomy or not did not affect the risk. Favourable effects were present for DLBCL (pooled OR = 0.66, 95% CI 0.54-0.80) and FL (pooled OR = 0.82, 95% CI 0.66-1.01).

CONCLUSION

Postmenopausal hormone therapy, particularly used close to menopause, is associated with a decreased risk of NHL.

Pancreatitis and pancreatic cancer risk: a pooled analysis in the International Pancreatic Cancer Case-Control Consortium (PanC4)

BACKGROUND

Pancreatitis is a known risk factor for pancreatic cancer; however, an unknown fraction of the disease is thought to be a consequence of tumor-related duct obstruction.

PATIENTS AND METHODS

A pooled analysis of a history of pancreatitis and risk of pancreatic cancer was carried out considering the time interval between diagnoses and potential modification by covariates. Adjusted pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated from 10 case-control studies (5048 cases of ductal pancreatic adenocarcinoma and 10,947 controls) taking part in the International Pancreatic Cancer Case-Control Consortium (PanC4).

RESULTS

The association between pancreatitis and pancreatic cancer was nearly three-fold at intervals of >2 years between diagnoses (OR: 2.71, 95% CI: 1.96-3.74) and much stronger at intervals of ≤2 years (OR: 13.56, 95% CI: 8.72-21.90) probably reflecting a combination of reverse causation and antecedent misdiagnosis of pancreas cancer as pancreatitis. The younger (<65 years) pancreatic cancer cases showed stronger associations with previous (>2 years) pancreatitis (OR: 3.91, 95% CI: 2.53-6.04) than the older (≥65 years) cases (OR: 1.68, 95% CI: 1.02-2.76; P value for interaction: 0.006).

CONCLUSIONS

Despite a moderately strong association between pancreatitis (diagnosed before >2 years) and pancreatic cancer, the population attributable fraction was estimated at 1.34% (95% CI: 0.612-2.07%), suggesting that a relatively small proportion of pancreatic cancer might be avoided if pancreatitis could be prevented.

Menstrual and reproductive factors, and hormonal contraception use: associations with non-Hodgkin lymphoma in a pooled analysis of InterLymph case-control studies

BACKGROUND

The two most common forms of non-Hodgkin lymphoma (NHL) exhibit different sex ratios: diffuse large B-cell lymphoma (DLBCL) occurs more frequently in men and follicular lymphoma (FL) more frequently in women. Looking among women alone, this pooled analysis explores the relationship between reproductive histories and these cancers.

MATERIALS AND METHODS

Self-reported reproductive histories from 4263 women with NHL and 5971 women without NHL were pooled across 18 case-control studies (1983-2005) from North America, Europe and Japan. Study-specific odd ratios (ORs) and confidence intervals (CIs) were estimated using logistic regression and pooled using random-effects meta-analyses.

RESULTS

Associations with reproductive factors were found for FL rather than NHL overall and DLBCL. In particular, the risk of FL decreased with increasing number of pregnancies (pooled OR(trend) = 0.88, 95% CI 0.81-0.96). FL was associated with hormonal contraception (pooled OR = 1.30, 95% CI 1.04-1.63), and risks were increased when use started after the age of 21, was used for <5 years or stopped for >20 years before diagnosis. DLBCL, on the other hand, was not associated with hormonal contraception (pooled OR = 0.87, 95% CI 0.65-1.16).

CONCLUSIONS

Hormonal contraception is associated with an increased risk of FL but not of DLBCL or NHL overall.

Cigarette smoking and pancreatic cancer: an analysis from the International Pancreatic Cancer Case-Control Consortium (Panc4)

BACKGROUND

To evaluate the dose-response relationship between cigarette smoking and pancreatic cancer and to examine the effects of temporal variables.

METHODS

We analyzed data from 12 case-control studies within the International Pancreatic Cancer Case-Control Consortium (PanC4), including 6507 pancreatic cases and 12 890 controls. We estimated summary odds ratios (ORs) by pooling study-specific ORs using random-effects models.

RESULTS

Compared with never smokers, the OR was 1.2 (95% confidence interval [CI] 1.0-1.3) for former smokers and 2.2 (95% CI 1.7-2.8) for current cigarette smokers, with a significant increasing trend in risk with increasing number of cigarettes among current smokers (OR=3.4 for ≥35 cigarettes per day, P for trend<0.0001). Risk increased in relation to duration of cigarette smoking up to 40 years of smoking (OR=2.4). No trend in risk was observed for age at starting cigarette smoking, whereas risk decreased with increasing time since cigarette cessation, the OR being 0.98 after 20 years.

CONCLUSIONS

This uniquely large pooled analysis confirms that current cigarette smoking is associated with a twofold increased risk of pancreatic cancer and that the risk increases with the number of cigarettes smoked and duration of smoking. Risk of pancreatic cancer reaches the level of never smokers ∼20 years after quitting.

Alcohol consumption and pancreatic cancer: a pooled analysis in the International Pancreatic Cancer Case-Control Consortium (PanC4)

BACKGROUND

Heavy alcohol drinking has been related to pancreatic cancer, but the issue is still unsolved.

METHODS

To evaluate the role of alcohol consumption in relation to pancreatic cancer, we conducted a pooled analysis of 10 case-control studies (5585 cases and 11,827 controls) participating in the International Pancreatic Cancer Case-Control Consortium. We computed pooled odds ratios (ORs) by estimating study-specific ORs adjusted for selected covariates and pooling them using random effects models.

RESULTS

Compared with abstainers and occasional drinkers (< 1 drink per day), we observed no association for light-to-moderate alcohol consumption (≤ 4 drinks per day) and pancreatic cancer risk; however, associations were above unity for higher consumption levels (OR = 1.6, 95% confidence interval 1.2-2.2 for subjects drinking ≥ 9 drinks per day). Results did not change substantially when we evaluated associations by tobacco smoking status, or when we excluded participants who reported a history of pancreatitis, or participants whose data were based upon proxy responses. Further, no notable differences in pooled risk estimates emerged across strata of sex, age, race, study type, and study area.

CONCLUSION

This collaborative-pooled analysis provides additional evidence for a positive association between heavy alcohol consumption and the risk of pancreatic cancer.

Cigar and pipe smoking, smokeless tobacco use and pancreatic cancer: an analysis from the International Pancreatic Cancer Case-Control Consortium (PanC4)

BACKGROUND

Cigarette smoking is the best-characterized risk factor for pancreatic cancer. However, data are limited for other tobacco smoking products and smokeless tobacco.

MATERIALS AND METHODS

We conducted a pooled analysis of cigar and pipe smoking and smokeless tobacco use and risk of pancreatic cancer using data from 11 case-control studies (6056 cases and 11,338 controls) within the International Pancreatic Cancer Case-Control Consortium (PanC4). Pooled odds ratios (OR) and the corresponding 95% confidence intervals (CI) were estimated by unconditional multiple logistic regression models adjusted for study center and selected covariates.

RESULTS

Compared with never tobacco users, the OR for cigar-only smokers was 1.6 (95% CI: 1.2-2.3), i.e. comparable to that of cigarette-only smokers (OR 1.5; 95% CI 1.4-1.6). The OR was 1.1 (95% CI 0.69-1.6) for pipe-only smokers. There was some evidence of increasing risk with increasing amount of cigar smoked per day (OR 1.82 for ≥ 10 grams of tobacco), although not with duration. The OR for ever smokeless tobacco users as compared with never tobacco users was 0.98 (95% CI 0.75-1.3).

CONCLUSION

This collaborative analysis provides evidence that cigar smoking is associated with an excess risk of pancreatic cancer, while no significant association emerged for pipe smoking and smokeless tobacco use.

Highly elevated PSA and dietary PhIP intake in a prospective clinic-based study among African Americans

African-American men die from prostate cancer (PC) nearly twice as often as white US men and consume about twice as much of the predominant US dietary heterocyclic amine, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a genotoxic rat-prostate carcinogen found primarily in well-cooked chicken and beef. To investigate the hypothesis that PhIP exposure increases PC risk, an ongoing prospective clinic-based study compared PC screening outcomes with survey-based estimates of dietary PhIP intake among 40-70-year-old African-American men with no prior PC in Oakland, CA. They completed food-frequency and meat-cooking/consumption questionnaires and had a prostate-specific antigen (PSA) test and digital-rectal exam. Results for 392 men indicated a 17 (+/-17) ng/kg day mean (+/-1 s.d.) daily intake of PhIP, about twice that of white US men of similar age. PhIP intake was attributable mostly to chicken (61%) and positively associated (R(2)=0.32, P<0.0001) with saturated fat intake. An odds ratio (95% confidence interval) of 31 (3.1-690) for highly elevated PSA > or =20 ng/ml was observed in the highest 15% vs lowest 50% of estimated daily PhIP intake (> or =30 vs < or =10 ng/kg day) among men 50+ years old (P=0.0002 for trend) and remained significant after adjustment for self-reported family history of (brother or father) PC, saturated fat intake and total energy intake. PSA measures were higher in African-American men with positive family history (P=0.007 all men, P<0.0001 highest PSA quartile). These preliminary results are consistent with a positive association between PhIP intake and highly elevated PSA, supporting the hypothesis that dietary intervention may help reduce PC risk.

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.

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.

A pooled analysis of 10 case-control studies of melanoma and oral contraceptive use

Data regarding the effects of oral contraceptive use on women's risk of melanoma have been difficult to resolve. We undertook a pooled analysis of all case-control studies of melanoma in women completed as of July 1994 for which electronic data were available on oral contraceptive use along with other melanoma risk factors such as hair colour, sun sensitivity, family history of melanoma and sun exposure. Using the original data from each investigation (a total of 2391 cases and 3199 controls), we combined the study-specific odds ratios and standard errors to obtain a pooled estimate that incorporates inter-study heterogeneity. Overall, we observed no excess risk associated with oral contraceptive use for 1 year or longer compared to never use or use for less than 1 year (pooled odds ratio (pOR)=0.86; 95% CI=0.74-1.01), and there was no evidence of heterogeneity between studies. We found no relation between melanoma incidence and duration of oral contraceptive use, age began, year of use, years since first use or last use, or specifically current oral contraceptive use. In aggregate, our findings do not suggest a major role of oral contraceptive use on women's risk of melanoma.

Rarity of CDK4 germline mutations in familial melanoma

To date, two genes have been implicated in melanoma pathogenesis. The first, CDKN2A, is a tumour suppressor gene with germline mutations detected in 20% of melanoma-prone families. The second, CDK4, is an oncogene with co-segregating germline mutations detected in only three kindreds worldwide. We examined 16 American melanoma-prone families for mutations in all coding exons of CDK4 and screened additional members of two previously reported families with the Arg24Cys germline CDK4 mutation to evaluate the penetrance of the mutation. No new CDK4 mutations were identified. In the two Arg24Cys families, the penetrance was estimated to be 63%. Overall, 12 out of 12 invasive melanoma patients, none out of one in situ melanoma patient, five out of 13 dysplastic naevi patients, two out of 15 unaffected family members, and none out of 10 spouses carried the Arg24Cys mutation. Dysplastic naevi did not strongly co-segregate with the Arg24Cys mutation. Thus the phenotype observed in melanoma-prone CDK4 families appears to be more complex than just the CDK4 mutation. Both genetic and environmental factors are likely to contribute to the occurrence of melanoma and dysplastic naevi in these families. In summary, although CDK4 is a melanoma susceptibility gene, it plays a minor role in hereditary melanoma.

Effect of highly active antiretroviral therapy on the natural history of anal squamous intraepithelial lesions and anal human papillomavirus infection

The effect of highly active antiretroviral therapy (HAART) on the natural history of anal squamous intraepithelial lesions (ASIL)-the likely anal cancer precursor-and anal human papillomavirus (HPV) infection is unknown. ASIL severity and level of anal HPV DNA were evaluated among HIV-positive men who have sex with men (MSM) for at least 6 months before initiation of HAART. The results were compared with those from a 6-month period after initiation of HAART. Anal swabs for cytology and HPV studies were obtained, followed by high-resolution anoscopy and biopsy. Among men whose most severe pre-HAART diagnosis was atypical squamous cells of undetermined significance or low-grade ASIL, 18% (confidence interval [CI], 6-31%, 7 of 38) progressed and 21% (CI, 8-34%, 8 of 38) regressed 6 months after starting HAART. Seventeen percent (CI, 0-38%, 2 of 12) of study subjects who began with a normal diagnosis developed ASIL. Only 4% (CI, 0-10%, 1 of 28) of study subjects with high-grade ASIL regressed to normal. There was no reduction in the proportion of study subjects who tested positive for HPV DNA or HPV DNA levels after HAART initiation. The ASIL and HPV data were similar to those of the pre-HAART comparison period. These results indicate that HAART has little effect on either ASIL or HPV in the first 6 months after HAART initiation.

DNA copy number alterations in HIV-positive and HIV-negative patients with diffuse large-cell lymphomas

Individuals infected with HIV are at increased risk of developing aggressive non-Hodgkin's lymphoma with a worse prognosis than those similarly afflicted without HIV infection. The underlying genetic differences in tumor behavior between these two groups are not known. We explored the hypothesis that lymphomas from HIV-positive individuals have distinct somatic genetic changes that may provide clues to the genetic basis of disease progression and outcome. Genome-wide DNA copy number alterations (CNAs) in primary tumors from 14 HIV-positive and 11 HIV-negative patients with diffuse large B-cell lymphoma (DLCL) were quantified using comparative genomic hybridization (CGH). Tumors from HIV-positive patients displayed fewer regional DNA-CNAs than those from patients who did not have HIV. When CNAs were present, they occurred at lower frequency in HIV-positive patients. Gains at chromosomes 8q and Xp were the most frequent changes in the HIV-negative group, and gains on 2p and 12q were common in the combined HIV-positive and HIV-negative groups. No alteration was specific to AIDS-related DLCL. These data suggest that fewer somatic genomic changes are needed for progression to DLCL in HIV-immunocompromised hosts, and that other factors, such as reduced immune surveillance, may contribute to neoplastic progression.

Prevalence and risk factors for anal squamous intraepithelial lesions in women

BACKGROUND

Anal cancers are thought to arise from squamous intraepithelial lesions in the anal canal, and women infected with human immunodeficiency virus-1 (HIV) may be at higher risk of anal cancer. Our aim was to determine the prevalence of human papillomavirus (HPV)-related abnormalities of the anal canal in women and to characterize risk factors for these lesions.

METHODS

We evaluated HPV-related abnormalities in 251 HIV-positive and in 68 HIV-negative women. We completed physical examinations and obtained questionnaire data on medical history and relevant sexual practices. Univariate and adjusted relative risks (RRs) and 95% confidence intervals (CIs) were computed using the Mantel-Haenszel procedure and regression techniques. All statistical tests were two-sided.

RESULTS

Abnormal anal cytology, including atypical squamous cells of undetermined significance, low-grade squamous intraepithelial lesions, or high-grade squamous intraepithelial lesions (HSILs), was diagnosed in 26% of HIV-positive and in 8% of HIV-negative women. HSILs were detected by histology or cytology in 6% of HIV-positive and in 2% of HIV-negative women. HIV-positive women showed increased risk of anal disease as the CD4 count decreased (P<.0001) and as the plasma HIV RNA viral load increased (P =.02). HIV-positive women with abnormal cervical cytology had an increased risk of abnormal anal cytology at the same visit (RR = 2.2; 95% CI = 1.4 to 3.3). Abnormal anal cytology in HIV-positive women was associated with anal HPV RNA detected by the polymerase chain reaction and by a nonamplification-based test (RR = 4.3; 95% CI = 1.6 to 11). In a multivariate analysis, the history of anal intercourse and concurrent abnormal cervical cytology also were statistically significantly (P =.05) associated with abnormal anal cytology.

CONCLUSIONS

HIV-positive women had a higher risk of abnormal anal cytology than did HIV-negative women with high-risk lifestyle factors. These data provide strong support for anoscopic and histologic assessment and careful follow-up of women with abnormal anal lesions.

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.

Prevalence and risk factors for anal human papillomavirus infection in human immunodeficiency virus (HIV)-positive and high-risk HIV-negative women

Little is known about the epidemiology of anal human papillomavirus (HPV) infection in women. We studied 251 human immunodeficiency virus (HIV)-positive and 68 HIV-negative women for the presence of anal HPV by use of polymerase chain reaction (PCR) and hybrid capture. Medical and behavioral risk factors were evaluated; 76% of HIV-positive and 42% of HIV-negative women were found to have anal HPV DNA via analysis by PCR (relative risk [RR], 1.8; 95% confidence interval [CI], 1.3-2.5). Among 200 women for whom there were concurrent anal and cervical HPV data, anal HPV was more common than cervical HPV in both HIV-positive (79% vs. 53%) and HIV-negative women (43% vs. 24%). By multivariate analysis of HIV-positive women, CD4(+) cell counts </=200 cells/mm(3), compared with counts >500 cells/mm(3) (RR, 1.4; 95% CI, 1.1-1.5), and cervical HPV infection (RR, 1.3; 95% CI, 1.1-1.4) were associated with anal HPV infection. Women >45 years old had reduced risk, compared with women <36 years old (RR, 0.80; 95% CI, 0.50-0.99), as did African American women (RR, 0.86; 95% CI, 0.72-1.0), compared with white women. Anal HPV infection is underrecognized in HIV-positive and high-risk HIV-negative women.

K-ras and p53 in pancreatic cancer: association with medical history, histopathology, and environmental exposures in a population-based study

Pancreatic cancer is a highly fatal cancer with few identified risk factors. Increased risk of pancreatic cancer in tobacco smokers and among diabetic patients is well established, and some reports have suggested associations with coffee consumption and occupational exposure to organochlorines. At present, there is little information regarding the possible association of these risk factors with the known genetic alterations found in pancreatic cancers, such as activation of the K-ras oncogene and inactivation of the p53 tumor suppressor gene. Knowledge of such relationships may help to understand the molecular pathways of pancreatic tumorigenesis. We investigated the association between these molecular defects and risk factors for pancreatic cancer in 61 newly diagnosed patients identified through an ongoing study of pancreatic cancer in the San Francisco Bay Area. Interview information was obtained regarding environmental exposures, medical history, and demographic factors. Serum levels of dichlorodiphenyltrichloroethylene (DDE) and polychlorinated biphenyls were available on a subset of 24 patients. Tumor blocks were located from local hospitals and used for K-ras mutational analysis at codon 12 and for p53 protein immunohistochemistry. The molecular analyses were facilitated through the use of laser capture microdissection, which provides a reliable method to obtain almost pure populations of tumor cells. Mutations in K-ras codon 12 were found in 46 (75%) of 61 pancreatic cancers. A prior diagnosis of diabetes was significantly associated with K-ras negative tumors (P = 0.002, Fisher's exact test). The absence of this mutation was also associated with increased serum levels of DDE, although this association was not statistically significant (P = 0.16, Wilcoxon's test). There was no difference in polychlorinated biphenyl levels between the K-ras wild-type and mutant groups. Immunohistochemical staining for p53 protein did not differ by patient characteristics or clinical history, but significant associations were found with poor glandular differentiation (P = 0.002, chi2 trend test), severe nuclear atypia (P = 0.0007, chi2 trend test), and high tumor grade (P = 0.004, chi2 trend test). Our results are suggestive of the presence of K-ras codon 12 mutation-independent tumorigenesis pathways in patients with prior diabetes and possibly in patients with higher serum levels of DDE. Our results also support a role for the p53 tumor suppressor protein in the maintenance of genomic integrity.

Childhood brain tumours and exposure to animals and farm life: a review

Brain tumours are the most common solid tumour in children. However, little is known about their aetiology, and only a small percentage of cases can be attributed to established risk factors. Exposure to farm animals and pets have been considered as possible risk factors for childhood brain tumour (CBT) development for several reasons. Numerous factors associated with farm life, including bacteria, pesticides, solvents and some animal oncogenic viruses, have been found to induce brain tumour formation in animals. Some studies have found viral gene sequences in human brain tumours. Epidemiological studies of brain tumours in adults have reported an increased risk among veterinarians and farmers. In this review, data are examined from seven case-control studies published between 1979 and 1998 that considered a possible relationship between fetal or childhood exposure to farm animals or pets and CBT. Five of the seven studies examined childhood farm residence or exposure of mother or child to farm animals and, of these five, four reported elevated risk for CBT with odds ratios (OR) ranging from 0.9 to 2.5 for maternal exposures and from 0.6 to 6.7 for children's exposures. Later studies that were larger subsequently examined histological type and reported excess risk for primitive neuroectodermal tumours (PNETs) with farm residence prenatally (OR = 3.7, CI = 0.8, 24) or in childhood (OR = 5.0, CI = 1.1, 4.7). Increased risk of PNET was also associated with maternal exposure to pigs (OR = 12, CI = .1, 47) or poultry (OR = 4.0, CI = 1.2, 13). The results of these studies showed few other consistent relationships between farm life or farm animals and CBT.

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.

Pancreatic cancer and serum organochlorine levels

Occupational exposure to p,p'-dichlorodiphenyltrichloroethane (DDT) has been associated with increased pancreatic cancer risk. We measured organochlorine levels in serum obtained at the study enrollment from 108 pancreatic cancer cases and 82 control subjects aged 32-85 years in the San Francisco Bay Area between 1996 and 1998. Cases were identified using rapid case-ascertainment methods; controls were frequency-matched to cases on age and sex via random digit dial and random sampling of Health Care Financing Administration lists. Serum organochlorine levels were adjusted for lipid content to account for variation in the lipid concentration in serum between subjects. Median concentrations of p,p'-dichlorodiphenyldichloroethylene (DDE, 1290 versus 1030 ng/g lipid; P = 0.05), polychlorinated biphenyls (PCBs; 330 versus 220 ng/g lipid; P<0.001), and transnonachlor (54 versus 28 ng/g lipid; P = 0.03) were significantly greater among cases than controls. A significant dose-response relationship was observed for total PCBs (P for trend <0.001). Subjects in the highest tertile of PCBs (> or =360 ng/g lipid) had an odds ratio (OR) of 4.2 [95% confidence interval (CI) = 1.8-9.4] compared to the lowest tertile. The OR of 2.1 for the highest level of p,p'-DDE (95% CI = 0.9-4.7) diminished (OR = 1.1; 95% CI = 0.4-2.8) when PCBs were included in the model. Because pancreatic cancer is characterized by cachexia, the impact of this on the serum organochlorine levels in cases is difficult to predict. One plausible effect of cachexia is bioconcentration of organochlorines in the diminished lipid pool, which would lead to a bias away from the null. To explore this, a sensitivity analysis was performed assuming a 10-40% bioconcentration of organochlorines in case samples. The OR associated with PCBs remained elevated under conditions of up to 25% bioconcentration.

Case-control study of non-Hodgkin's lymphoma among women and heterosexual men in the San Francisco Bay Area, California

A population-based case-control study was conducted between 1988 and 1995 in the San Francisco Bay Area of California to determine risk factors for non-Hodgkin's lymphoma. Participants completed in-person interviews, and blood was drawn to test for viruses and lymphocyte subsets. This report includes data for 1,281 cases and 2,095 controls. In multivariate analyses, the factors associated with a decreased risk for non-Hodgkin's lymphoma were allergy to plants, bee and wasp stings, five or more vaccinations, drugs to lower blood cholesterol, nonsteroidal anti-inflammatory drugs, total number of sexual partners, and lifetime marijuana use, whereas an increased risk was associated with cimetidine and other histamine H2-receptor antagonists, splenectomy, gonorrhea, and body mass index. Unique to sex-specific models was an increased risk for endocrine gland disorders among women and for polio among men. Median CD3, CD4, CD8, CD20, and lymphocyte counts for non-Hodgkin's lymphoma patients were significantly lower than those for controls. These results implicate environmental factors that may influence the early stages of lymphomagenesis by stimulating the immune system. Antigen-driven B cells that accumulate to form lymphoma may be suppressed by immunologic stresses such as exposure to an increased number of sexual partners and to certain medications. A history of allergies provides evidence for a persistent capacity for B-cell differentiation and therefore a decreased accumulation of B cells. The decreased risk for non-Hodgkin's lymphoma with use of nonsteroidal anti-inflammatory drugs and cholesterol-lowering drugs is consistent with a macrophage inflammatory role in B-cell proliferation.

A population based, case control study of non-Hodgkin's lymphoma in patients with rheumatoid arthritis

OBJECTIVE

Epstein-Barr virus (EBV) associated lymphoproliferative disorders (LPD) similar to those that occur in immunosuppressed solid organ recipients have been reported in patients with rheumatoid arthritis (RA). These LPD cause significant morbidity and/or mortality in a state of sustained immunosuppression, but may spontaneously regress if immunocompetence is restored. We determined the population based frequency of EBV associated LPD relative to all non-Hodgkin's lymphomas (NHL) that occur in the general population of patients with RA.

METHODS

Forty-two case patients with NHL and RA and 49 control patients with NHL and no RA were identified in a population based, case control study of NHL that occurred in a 6 county Northern California area during the years 1988-94. The lymphoma tissue specimens were reviewed and the diagnosis of NHL was confirmed. In addition, the specimens were analyzed for NHL grade, histologic subtype, histopathologic features associated with immunosuppression, immunophenotype, and the presence of EBV genome in the tumor cells.

RESULTS

No significant differences were identified between NHL in the RA case group and the control group (no RA) with respect to any variables investigated. One patient (2%) in the case group and one (2%) in the control group developed LPD containing EBV.

CONCLUSION

Our findings reveal that EBV associated lymphomas represent only a small fraction of all NHL in the general RA patient population. EBV associated LPD should be recognized when they occur because they require a special approach to patient management. However, these data indicate that the majority of NHL that occurs in patients with RA is probably coincidental with RA and not the result of significant immunosuppression.

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.

Prenatal vitamin supplementation and risk of childhood brain tumors

An international case-control study of primary pediatric brain tumors included interviews with mothers of cases diagnosed from 1976 to 1994 and mothers of population controls. Data are available on maternal vitamin use during pregnancy for 1,051 cases and for 1,919 controls from 8 geographic areas in North America, Europe and Israel. While risk estimates varied by study center, combined results suggest that maternal supplementation for 2 trimesters decreased risk of brain tumor [odds ratio (OR) = 0.7; 95% confidence interval (CI) = 0.5, 0.9], with a trend of less risk with longer duration of use (p trend = 0.0007). The greatest risk reduction was among children diagnosed under 5 years of age whose mothers used supplements during all 3 trimesters (OR = 0.5; CI = 0.3, 0.8). This effect did not vary by histology and was seen for supplementation during pregnancy rather than during the month before pregnancy or while breastfeeding. Our findings are largely driven by data from the United States, where most mothers took vitamins. The proportion of control mothers who took vitamins during pregnancy varied markedly from 3% in Israel and in France, 21% in Italy, 33% in Canada and 52% in Spain to 86-92% at the 3 U.S. centers. The composition of the various multivitamin compounds taken also varied: daily dose of vitamin C ranged from 0 to 600 mg; vitamin E from 0 to 70 mg; vitamin A from 0 to 30,000 IU; and folate from 0 to 2,000 micrograms. Mothers also took individual micronutrient supplements (e.g., vitamin C tablets), but most mothers who took these also took multivitamins, making it impossible to determine the potential independent effects of these micronutrients.

Hair-color products and risk for non-Hodgkin's lymphoma: a population-based study in the San Francisco bay area

OBJECTIVES

As part of a large, epidemiologic study of non-Hodgkin's lymphoma, this study investigated a possible association between use of hair-color products and non-Hodgkin's lymphoma.

METHODS

A population-based case-control study was conducted in the San Francisco Bay area. Of 4108 participants, 2544 were questioned about use of hair-color products. Control subjects were identified by use of random-digit dialing.

RESULTS

Ever use of hair-color products was reported by 56% of case and 56% of control women and 10% of case and 9% of control men. Risks were not elevated for women for use of any hair-color products. Men who ever used semipermanent hair color had slightly elevated risks for non-Hodgkin's lymphoma, with trends associated with greater lifetime frequency of use and frequency of use per year, although individual confidence intervals overlapped unity. These elevated risks were diminished with exclusive use of semipermanent products, and confidence intervals overlapped unity.

CONCLUSIONS

Integration of our results with those from experimental animal studies and other epidemiologic studies provides little convincing evidence linking non-Hodgkin's lymphoma with normal use of hair-color products in humans.

Prenatal vitamin supplementation and pediatric brain tumors: huge international variation in use and possible reduction in risk

An international case-control study of primary pediatric brain tumors included interviews with mothers of cases diagnosed from 1976-1994 and mothers of population controls. Data are available on maternal vitamin use during pregnancy for 1051 cases and for 1919 controls in eight geographic areas of North America, Europe and Israel. While risk estimates varied by study center, combined results suggest that maternal supplementation for two trimesters may decrease risk of brain tumor [odds ratio (OR)=0.7; 95% confidence interval (CI)=0.5-0.9], with a trend toward less risk with longer duration of use (P trend= 0.0007). The greatest risk reduction was among children diagnosed under 5 years of age whose mothers used supplements during all three trimesters (OR=0.5; CI=0.3- 0.8). This effect did not vary by histology and was seen for supplementation during pregnancy rather than during the month before pregnancy or while breast feeding. These findings are largely driven by data from the US, where most mothers took vitamins. The proportion of control mothers who took vitamins during pregnancy varied tremendously, from 3% in Israel and in France through 21% in Italy, 33% in Canada, 52% in Spain to 86-92% at the three US centers. The composition of the various multivitamin compounds taken also varied: daily dose of vitamin C ranged from 0 up to 600 mg; vitamin E from 0 to 70 mg; vitamin A from 0 to 30,000 IU and folate from 0 to 2000 mg. Mothers also took individual micronutrient supplements (e.g., vitamin C tablets), but most mothers who took these also took multivitamins, making it impossible to determine potential independent effects of these micronutrients.

Farm and animal exposures and pediatric brain tumors: results from the United States West Coast Childhood Brain Tumor Study

Nineteen counties from San Francisco and Los Angeles, California and Seattle, Washington were the United States sites for a large population-based case-control study of childhood brain tumors (CBTs), sponsored by the National Cancer Institute. CBT patients who were < 20 years of age and were diagnosed between 1984 and 1991 were reported to each region's cancer registry. The 801 control subjects were obtained by random digit dial and were frequency-matched to the 540 CBT patients in San Francisco and Seattle (one patient to two controls) and in Los Angeles (one patient to one control). Data collected by in-person interview with subjects' mothers were analyzed to investigate an association between risk for CBTs and life on a farm, exposure to farm animals (dairy cattle, beef cattle, pigs, sheep/goats, poultry, and horses), and some cat and non-farm horse exposures. Elevated risks for CBTs were observed in association with mothers' exposure to pigs [odds ratio (OR) = 3.8, 95% confidence interval (CI) = 1.2-12] and horses (OR = 2.2, 95% CI = 1.0-4.8) on a farm during the index pregnancy. Children diagnosed with primitive neuroectodermal tumors showed elevated risks for CBTs with personal and maternal prenatal exposure to pigs (child, OR = 4.0, 95% CI = 1.2-13; mother, OR = 11.9, 95% CI = 2.8-51) and poultry (child, OR = 3.0, 95% CI = 1.1-8.0; mother, OR = 4.0, 95% CI = 1.2-14). No other animal exposures of children or mothers were found to be consistently related to CBTs. Children diagnosed with primitive neuroectodermal tumors who were on a farm for > 1 year and were first on a farm when they were < 6 months of age also had increased risk for CBTs (OR = 3.9, 95% CI = 1.2-13). A somewhat increased risk for CBTs was found for children of mothers who ever had worked on livestock farms compared with mothers who never had worked on a farm (OR = 7.4, 95% CI = 0.86-64, based on five case mothers and one control mother who worked on livestock farms during the 5 years preceding the birth of the index child). The associations are consistent with those of two previous studies in Norway (P. Kristensen et al., Int. J. Cancer, 65: 39-50, 1996) and the United States and Canada (G. R. Bunin et al., Cancer Epidemiol. Biomark. Prev., 3: 197-204, 1994) that investigated the role of farm-related exposures in the etiology of CBTs.

Results from an international case-control study of childhood brain tumors: the role of prenatal vitamin supplementation

An international case-control study of primary pediatric brain tumors included interviews with mothers of cases diagnosed from 1976 to 1994 and mothers of population controls. Data are available on maternal vitamin use during pregnancy for 1051 cases and 1919 controls from eight geographic areas in North America, Europe, and Israel. Although risk estimates varied by study center, combined results suggest that maternal supplementation for two trimesters may decrease risk of brain tumor (odds ratio [OR] 0.7, 95% confidence interval [CI] 0.5-0.9), with a trend of less risk with longer duration of use (p trend = 0.0007). The greatest risk reduction was among children diagnosed under 5 years of age whose mothers used supplements during all three trimesters (OR 0.5, CI 0.3-0.8). This effect did not vary by histology and was seen for supplementation during pregnancy rather than during the month before pregnancy or while breast feeding. These findings are largely driven by data from the United States, where most mothers took vitamins. The proportion of control mothers who took vitamins during pregnancy varied tremendously: from 3% in Israel and France, 21% in Italy, 33% in Canada, 52% in Spain and 86 to 92% at the three U.S. centers. The composition of the various multivitamin compounds taken also varied: the daily dose of vitamin C ranged from 0 to 600 mg, vitamin E ranged from 0 to 70 mg, vitamin A ranged from 0 to 30,000 IU, and folate ranged from 0 to 2000 micrograms. Mothers also took individual micronutrient supplements (e.g., vitamin C tablets), but most mothers who took these also took multivitamins, making it impossible to determine potential independent effects of these micronutrients.

Virologic, immunologic, and clinical parameters in the incidence and progression of anal squamous intraepithelial lesions in HIV-positive and HIV-negative homosexual men

Anal cancer may be preceded by anal squamous intraepithelial lesions (ASIL), but the natural history of ASIL is poorly understood. In this report, we characterize the 2-year incidence and progression of low-grade SIL (LSIL) and high-grade SIL (HSIL) in a cohort study in 346 HIV-positive and 262 HIV-negative homosexual or bisexual men. Subjects were studied at defined intervals using anal cytology, anoscopy with biopsy of visible lesions, human papillomavirus (HPV) testing, HIV serostatus, CD4 level, and data on medical history and lifestyle. The incidence of HSIL within 2 years was 20% in HIV-positive men and 8% in HIV-negative men who were normal at baseline. In total, 62% of HIV-positive and 36% of HIV-negative men with LSIL at baseline progressed to HSIL. The relative risk (RR) for anal disease progression in HIV-positive men was 2.4 (95% confidence interval [CI], 1.8-3.2) when compared with HIV-negative men. The RR increased to 3.1 (95% CI, 2.3-4.1) in HIV-positive men with CD4 counts <200/mm3. Infection with multiple HPV types was a risk factor for anal disease progression in both HIV-positive (RR = 2.0; 95% CI, 1.0-4.1) and HIV-negative (RR = 5.1; 95% CI, 2.3-11) men. The incidence of anal HSIL and progression of LSIL to HSIL within 2 years of follow-up is high in HIV-positive homosexual or bisexual men and to a lesser extent, in HIV-negative men. Men with the above risk factors may be at increased risk of developing anal cancer.

Anal squamous intraepithelial lesions in HIV-positive and HIV-negative homosexual and bisexual men: prevalence and risk factors

Anal cancer is more commonly found in homosexual and bisexual men than cervical cancer is in women. Invasive anal cancer may be preceded by anal squamous intraepithelial lesions (ASIL), and treatment of ASIL may prevent the development of anal cancer. We characterized the prevalence and risk factors for ASIL in 346 HIV-positive and 262 HIV-negative homosexual men. Anal cytology, biopsy of visible anal lesions, and human papillomavirus (HPV) tests were performed, and data on HIV serostatus, CD4 count, and medical and lifestyle history were collected. ASIL was diagnosed in 36% of HIV-positive men and 7% of HIV-negative men (relative risk [RR] = 5.7; 95% confidence interval [CI], 3.6-8.9). Among HIV-positive men, the RR for ASIL increased with lower CD4 levels but was elevated even in men with CD4 levels >500/mm3 (RR = 3.8; 95% CI, 2.1-6.7) when compared with HIV-negative men. High-level HPV infection, as measured by detection of both hybrid capture (HC) group A and group B types, was another significant risk factor for ASIL in both HIV-positive men (RR = 8.8; 95% CI, 2.3-35) and HIV-negative men (RR = 20; 95% CI, 5.5-71) when compared with HC-negative men. HIV-negative men with anal HPV infection and HIV-positive men, regardless of CD4 level, are at high risk for ASIL.

Parental occupation and childhood brain tumors: astroglial and primitive neuroectodermal tumors

Data from a population-based case-control study in 19 counties in California and Washington State were used to investigate the association between parental employment and childhood brain tumors. Parents of 540 cases (including 308 astroglial and 109 primitive neuroectodermal tumors) and 801 controls diagnosed from 1984 to 1991 were interviewed. Analysis was completed for parents' self-reported industry of employment and job tasks during the five years preceding the birth of the child. Parents who worked in the chemical industry were at increased risk of having had children with astroglial tumors (fathers' odds ratio [OR] = 2.1; 95% confidence interval [CI], 1.1-3.9); mothers' OR = 3.3; 95% CI, 1.4-7.7), but no trend by duration of employment was seen for mothers. Children of fathers employed as electrical workers were at increased risk of developing brain tumors of any histologic type (OR = 2.3; 95% CI, 1.3-4.0).

High incidence of anal high-grade squamous intra-epithelial lesions among HIV-positive and HIV-negative homosexual and bisexual men

OBJECTIVE

The incidence of anal cancer among homosexual men exceeds that of cervical cancer in women, and HIV-positive homosexual men may be at even higher risk than HIV-negative men. Cervical cancer is preceded by high-grade squamous intra-epithelial lesions (HSIL) and anal HSIL may similarly be the precursor to anal cancer. In this study, we describe the incidence of and risk factors for HSIL in HIV-positive and HIV-negative homosexual and bisexual men.

DESIGN

Prospective cohort study of HIV-positive and HIV-negative homosexual men.

SETTING

The University of California, San Francisco.

PATIENTS

346 HIV-positive and 262 HIV-negative men enrolled at baseline, 277 HIV-positive and 221 HIV-negative homosexual men followed after baseline.

STUDY DESIGN

A questionnaire was administered detailing lifestyle habits, medical history and sexual practices. Anal swabs for cytology and human papillomavirus studies were obtained, followed by biopsies of visible lesions. Human papillomavirus testing was performed using polymerase chain reaction (PCR) and 'hybrid capture'. Blood was obtained for HIV testing and measurement of CD4 levels.

MAIN OUTCOME MEASURES

Incident HSIL.

RESULTS

HIV-positive men were more likely to develop HSIL than HIV-negative men relative risk (RR), 3.7; 95% confidence interval (CI), 2.6-5.7. Life-table estimates of the 4-year incidence of HSIL was 49% (95% CI, 41-56) among HIV-positive men and 17% (95% CI, 12-23) among HIV-negative men. Among HIV-positive men, those with lower baseline CD4 counts (P = 0.007) and persistent infection with one or more human papillomavirus types, determined using PCR (P = 0.0001), were more likely to develop HSIL.

CONCLUSIONS

HIV infection, lower CD4 levels and human papillomavirus infection were associated with high rates of incident HSIL among homosexual men. However, high rates were found at all CD4 levels among HIV-positive men and among HIV-negative men.

Prevalence and risk factors for human papillomavirus infection of the anal canal in human immunodeficiency virus (HIV)-positive and HIV-negative homosexual men

One of the groups at highest risk of anal cancer is homosexual and bisexual men. Like cervical cancer, anal cancer is associated with human papillomavirus (HPV) infection. Anal HPV infection was characterized in a study of 346 human immunodeficiency virus (HIV)-positive and 262 HIV-negative homosexual and bisexual men. Anal HPV DNA was detected in 93% of HIV-positive and 61% of HIV-negative men by polymerase chain reaction. The spectrum of HPV types was similar in HIV-positive and HIV-negative men, with HPV-16 the most common type. Infection with multiple HPV types was found in 73% of HIV-positive and 23% of HIV-negative men. Among HIV-positive men who were positive by hybrid capture for group B HPV types (16/18/31/33/35/39/45/51/52/56/58) or group A types (6/11/42/43/44), lower CD4 cell levels were associated with higher levels of group B DNA (P = .004) but not group A DNA. These data suggest increased replication of the more oncogenic HPV types with more advanced immunosuppression.

A study of pediatric brain tumors and their association with epilepsy and anticonvulsant use

OBJECTIVES

To evaluate the risk of childhood brain tumor occurrence in relation to epilepsy and anticonvulsant use.

STUDY DESIGN

As part of a multicenter case-control study of pediatric brain tumors, maternal report on epilepsy occurrence before diagnosis of her child's brain tumor was collected for 540 cases and compared with 801 control children. Mothers also reported on any long-term (> or = 2 weeks) use of medications by her child before the date of tumor diagnosis (or a comparable reference date for controls) and these medications were classified according to whether they contained barbiturates.

RESULTS

As expected, because seizures are often an early brain tumor symptom, a strong association was observed between epilepsy and brain tumor occurrence (odds ratio, OR = 6.2; 95% confidence limit, CL = 2.9, 14). The association remained elevated even after a > or = 10-year interval between diagnoses of epilepsy and brain tumor (OR = 4.7; CL = 0.8, 48). Elevated odds ratios were observed both for epileptic children who were treated with anticonvulsants containing barbiturates (OR = 5.8; CL = 2.2, 18) and for those not treated with barbiturates (OR = 7.9; CL = 1.7, 74), relative to nonepileptic children.

CONCLUSION

Whereas most of the brain tumor risk associated with epilepsy may be due to occult tumors, the finding of an elevated risk many years after diagnosis of epilepsy is of interest.

Colposcopic appearance of anal squamous intraepithelial lesions: relationship to histopathology

PURPOSE

The incidence of anal cancer is increased in men with a history of anal receptive intercourse. Analogous to cervical cancer, whose precursor is cervical high-grade squamous intraepithelial lesion (HSIL), anal cancer may be preceded by anal HSIL. Although not yet proven, detection, follow-up, and treatment of HSIL may prevent development of anal cancer. Cervical colposcopic methodology was used to describe anal lesions and to determine if HSIL could be distinguished from low-grade squamous intraepithelial lesion (LSIL).

METHODS

The colposcopic characteristics of 385 biopsied anal lesions were described and correlated with results of histopathology in a cohort of 121 human immunodeficiency virus-positive and 31 human immunodeficiency-negative homosexual/bisexual men with anal lesions followed as part of a longitudinal study of anal squamous intraepithelial lesions. Color, contour, surface, and vascular patterns of anal lesions were analyzed and correlated with histologic diagnosis.

RESULTS

Sixty-seven percent of biopsies showed LSIL and 26 percent showed HSIL. The positive predictive value for anal HSIL in lesions with characteristics typical of cervical LSIL was 7.7 percent (95 percent confidence interval, 1.8-14), whereas the positive predictive value for anal HSIL in lesions with characteristics typical of cervical HSIL was 49 percent (95 percent confidence interval, 40-58).

CONCLUSIONS

The colposcopic appearance of different grades of anal squamous intraepithelial lesions was similar to those described for the cervix. Incorporation of colposcopy into assessment of anal disease could aid in distinguishing anal LSIL from HSIL.

Comparison of conventional cytologic smears and ThinPrep preparations from the anal canal

OBJECTIVE

To compare anal cytology prepared via conventional methods and the ThinPrep processor.

STUDY DESIGN

Cells from the anal canal were collected using a moistened swab. One hundred thirty-six samples were collected from 133 gay or bisexual men; 102 were human immunodeficiency virus seropositive. A conventional smear was prepared and fixed in 95% ethanol. The residual cells on the swab were collected for thin-layer preparation using the Cytyc processor.

RESULTS

The diagnoses made from the conventional smears and thin layers agreed in 113 of 136 cases. An additional 19 cases were classified within one diagnostic category of each other. Two cases of low grade squamous epithelial lesion (SIL) diagnosed on the ThinPrep were judged negative on the conventional smear. Similarly, two cases of low grade SIL diagnosed on the conventional smear were judged negative on the thin-layer preparations. Rectal columnar cells were present on 127 of the ThinPrep samples but on only 113 of the conventional smears.

CONCLUSION

ThinPrep and conventional smears of the anal canal yielded similar diagnoses. Rectal columnar cells were more frequently encountered on the thin layers; their presence is an indication that the rectal transformation zone may have been adequately sampled. In addition, the ThinPrep technique reduces fecal and bacterial contamination and air-drying artifact, which frequently hinder cytologic evaluation of the anal canal.

Non-Hodgkin's lymphoma in homosexual men in the San Francisco Bay Area: occupational, chemical, and environmental exposures

Chemical, occupational, and other exposures as risk factors for non-Hodgkin's lymphoma (NHL) among homosexual men are reported from a population-based case-control study of 1593 eligible subjects with NHL and 2515 control subjects conducted in the San Francisco Bay Area between 1988 and 1995. Results are presented for 312 homosexual men with NHL and 420 homosexual control subjects. HIV-positive patients were less likely than control subjects to have worked in technical, sales, and administrative occupations; service occupations; and precision production, craft, or repair-related occupations. They were likely to have had less exposure to petroleum products, aldehydes, cleaning solvents, adhesives, insecticides, welding fumes, and tar, pitch, soot, or ash. The HIV-negative patients were less likely than the control subjects to have worked in managerial or professional specialty occupations and in technical, sales, or administrative occupations. HIV-negative patients were somewhat more likely than control subjects to have been exposed to herbicides (OR = 2.0, CI = 0.89 to 4.7), to radioactivity (OR = 4.7, CI = 1.7 to 13), and to tar, soot, pitch, or ash (250+ hours: OR = 2.3, CI = 0.96 to 5.6). HIV-negative NHL patients also were somewhat more likely to have lived on a farm as children than the control subjects (OR = 2.4, CI = 1.0 to 5.6). Pooled over HIV status, patients were somewhat more likely to have worked as motor vehicle or rail operators for more than 1 year (OR = 2.1, CI = 0.98 to 4.4). Most occupational exposures were of brief duration and many chemical exposures were reported as minimal. No clear and strong associations were found, although the risk for NHL related to exposure to several chemicals generally was reduced among HIV-positive men and elevated among HIV-negative men.

Non-Hodgkin's lymphoma in HIV-positive and HIV-negative homosexual men in the San Francisco Bay Area: allergies, prior medication use, and sexual practices

Lifestyle, sexual history, and medical history characteristics were analyzed as risk factors for non-Hodgkin's lymphoma (NHL) in a population-based case-control study of 1593 subjects with NHL and 2515 control subjects conducted in the San Francisco Bay Area between 1988 and 1995. The results for homosexual men, 312 with NHL and 420 control subjects, showed that HIV infection was associated with a 20-fold increased risk for NHL. Among HIV-positive homosexual men, after adjustment for other factors, those that were associated with a reduced risk for NHL were frequency of receptive anal intercourse between the ages of 20 and 29 (1 to 9 times: OR = 0.63; > or = 10 times: OR = 0.37; trend: p = 0.02), allergy to grass, hay, leaves, plants and pollen (OR = 0.35, CI = 0.19 to 0.64), number of bee or wasp stings (1 to 3 times: OR = 0.65; > or =4 times: OR = 0.56; trend: p = 0.07), use of Tagamet (cimetidine) for 4 consecutive weeks or longer (OR = 0.39, CI = 0.17 to 0.89), vaccination against influenza (OR = 0.41, CI = 0.23 to 0.74), and lifetime frequency of amphetamine use (1 to 19 times: OR = 0.59; > or =20 times: OR = 0.38; trend: p = 0.003). Among HIV-negative homosexual men, after adjustment for other factors, factors that were associated with NHL status were frequency of receptive anal intercourse between the ages of 20 and 29 (1 to 9 times: OR = 0.39; > or =10 times: OR = 0.20; trend: p = 0.001), nonmedication allergies (OR = 0.43, CI = 0.21 to 0.89), vaccination against poliomyelitis at <10 years (OR = 0.41, CI = 0.17 to 0.99), and having five or more siblings (OR = 3.6, CI = 1.7 to 7.7). An increased immunosuppressive effect of seminal fluid on sensitive rectal tissue and support from earlier work suggesting that HIV-related lymphomas may be outgrowths of antigen-driven B cells provide a possible mechanism for the results of this study. The role of allergic reactions in NHL is likely to be complex and may be related to B-cell differentiation. These associations may provide insight into an antigen-driven process early in lymphomagenesis.

Anal cytological abnormalities and anal HPV infection in men with Centers for Disease Control group IV HIV disease

OBJECTIVE

To characterise risk factors for abnormal and cytology and anal human papilloma virus (HPV) infection in homosexual/bisexual men with advanced HIV related immunosuppression.

DESIGN

Cross sectional study of men with Centers for Disease Control group IV HIV disease.

SETTING

The University of California San Francisco, AIDS Clinic.

PATIENTS

129 homosexual or bisexual men with group IV HIV disease.

METHODS

A questionnaire was administered detailing tobacco, alcohol and recreational drug use, medical history, and sexual practices. Anal swabs for cytology and HPV studies were obtained, as was blood for CD4 levels.

MAIN OUTCOME MEASURES

Abnormal anal cytology and anal HPV infection.

RESULTS

Abnormal anal cytology was detected in 39% of subjects and anal HPV infection in 93% as measured by polymerase chain reaction (PCR). Risk factors for abnormal cytology in multivariate analysis included HPV 16/18 infection (measured by PCR, RR = 2.1, 95% CI = 1.2-3.5) and intravenous drug use (RR = 1.8, 95% CI = 1.2-2.7). Infection with HPV 6/11 also had significantly elevated RRs in a separate model. Cigarette smoking, alcohol use, recreational drug use, and low CD4 level were associated with abnormal anal cytology in univariate analysis, as was infection with multiple HPV types and high levels of hybrid capture group B viral DNA.

CONCLUSIONS

Anal cytological abnormalities and HPV infection are common among homosexual/bisexual men with group IV HIV disease. In this study population, the main risk factors for abnormal cytology were HPV infection and intravenous drug use.

Clinically recognized dysplastic nevi. A central risk factor for cutaneous melanoma

OBJECTIVE

To investigate the relationship of number and type of nevi to the development of melanoma.

DESIGN

Case-control study.

SETTING

Outpatient clinics in referral hospitals.

PATIENTS

Cases were 716 consecutive patients with newly diagnosed melanoma identified at 2 melanoma centers between January 1, 1991, and December 31, 1992. Stratified random sampling of patients from outpatient clinics was used to identify 1014 participating controls of the same age, sex, race, and geographic distribution as the melanoma cases. All study subjects underwent an interview, a complete skin examination, photography of the most atypical nevi, and, if the patient was willing, a biopsy of the most atypical nevus.

MAIN OUTCOME MEASURES

Number and type of nevi on the entire body were systematically reported. All diagnoses of clinically dysplastic nevi were confirmed by expert examiners.

RESULTS

Risk for melanoma was strongly related to number of small nevi, large nondysplastic nevi, and clinically dysplastic nevi. In the absence of dysplastic nevi, increased numbers of small nevi were associated with an approximately 2-fold risk, and increased numbers of both small and large nondysplastic nevi were associated with a 4-fold risk. One clinically dysplastic nevus was associated with a 2-fold risk (95% confidence interval, 1.4-3.6), while 10 or more conferred a 12-fold increased risk (95% confidence interval, 4.4-31). Congenital nevi were not associated with increased risk of melanoma.

CONCLUSIONS

Although nondysplastic nevi confer a small risk, clinically dysplastic nevi confer substantial risk for melanoma. On the basis of nevus number and type, clinicians can identify a population at high risk of this epidemic cancer for screening and intervention.

Anal cytology as a screening tool for anal squamous intraepithelial lesions

Anal squamous intraepithelial lesions (ASIL) are common in homosexual and bisexual men, and high-grade ASIL (HSIL) in particular may represent an anal cancer precursor. Cervical cytology is a useful screening tool for detection of cervical HSIL to prevent cervical cancer. To assess anal cytology as a screening tool for anal disease, we compared anal cytology with anoscopy and histopathology of anal biopsies. A total of 2958 anal examinations were performed on 407 HIV-positive and 251 HIV-negative homosexual or bisexual men participating in a prospective study of ASIL. The examination consisted of a swab for anal cytology and anoscopy with 3% acetic acid and biopsy of visible lesions. Defining abnormal cytology as including atypical squamous cells of undetermined significance and ASIL, the sensitivity of anal cytology for detection of biopsy-proven ASIL was 69% (95% confidence interval: 60 to 78) in HIV-positive and 47% (95% confidence interval; 26 to 68) in HIV-negative men at their first visit and was 81% and 50%, respectively, for all subsequent visits combined. The absence of columnar cells did not affect the sensitivity, specificity, or predictive value of anal cytology. Anal cytology may be a useful screening tool to detect ASIL, particularly in HIV-positive men. The grade of disease on anal cytology did not always correspond to the histologic grade, and anal cytology should be used in conjunction with histopathologic confirmation.

Incidence of cutaneous melanoma among non-Hispanic whites, Hispanics, Asians, and blacks: an analysis of california cancer registry data, 1988-93

Cutaneous malignant melanoma occurs less frequently among non-White populations than among Whites. As a result, little is known about the incidence and epidemiology of melanoma among other race/ethnicity groups. Data from the California Cancer Registry (United States) among 879 Hispanic, 126 Asian, and 85 Black men and women diagnosed with melanoma in 1988-93 were analyzed and compared with data for 17,765 non-Hispanic White cases. Average, annual, age-adjusted incidence rates per 100,000 population were 17.2 for men (M) and 11.3 for women (W) for non-Hispanic Whites; 2.8 (M), 3.0 (W) for Hispanics; 0.9 (M), 0.8 (W) for Asians; and 1.0 (M), 0.7 (W) for non-Hispanic Blacks. Among men, melanoma occurred on the lower extremity for 20 percent of Hispanics, 36 percent of Asians, and 50 percent of Blacks compared with nine percent of non-Hispanic Whites, with similar but less pronounced differences in site distribution by race/ethnicity for women. Among men, melanoma was diagnosed after it had metastasized to a remote site for 15 percent of Hispanics, 13 percent of Asians, and 12 percent of Blacks, compared with six percent of non-Hispanic Whites. Among women, seven percent of Hispanics, 21 percent of Asians, and 19 percent of Blacks were diagnosed with late-stage melanoma compared with four percent of non-Hispanic Whites. Although histologic type was not specified for nearly half of the cases, Hispanic, Asian, and Black patients were more likely than non-Hispanic White patients to have been diagnosed with acral lentiginous melanoma. Melanoma among Hispanics, Asians, and Blacks differs in incidence, site distribution, stage at diagnosis, and histologic type from melanoma among non-Hispanic Whites, and identification of risk factors for melanoma in these race/ ethnicity groups would elucidate further the role of sun and other factors in the etiology of melanoma.

Patient outcomes after spinal reconstructive surgery in patients > or = 40 years of age

This study provides outcome data on the quality of life in 84 patients 40 years of age or older who had spinal reconstructive surgery. A 30-min questionnaire covering the patients' pre- and postoperative functional status, expectations for surgery, medication use, quality of life, and overall satisfaction was administered via telephone by a trained interviewer. Clinical data were obtained from chart and radiographic review. The majority of the patients had back or leg pain as their indication for surgery. Diagnoses included kyphosis, scoliosis, spinal stenosis, spondylolisthesis, and failed surgery. Overall satisfaction with functional status and surgical outcome was 81%, and there was significant improvement in most functional measures. This study suggests that improved qualify of life for the majority of appropriately selected spinal reconstruction patients is achievable in this mature population.

Head injury as a risk factor for brain tumors in children: results from a multicenter case-control study

We evaluated the risk of brain tumor occurrence in relation to previous head injury in a population-based case-control study of 540 children with a primary brain tumor and 801 control children. The risk of a brain tumor among children with a previous head injury that resulted in medical attention was slightly elevated when compared with children with no reported head injury [odds ratio (OR) = 1.4; 95% confidence limits (CL) = 1.0, 1.9]. This effect was stronger when we restricted the head-injured group to the few children with loss of consciousness (OR = 1.6; 95% CL = 0.6, 3.9) or an overnight admission to a hospital (OR = 1.7; 95% CL 0.7, 4.6), relative to those with no head injury. We observed no appreciable association between brain tumor occurrence and birth injury involving the head or a forceps delivery. Among the few children with either a birth injury or forceps delivery and a subsequent head injury, we observed approximately twofold elevations in risk. The OR was 2.6 (95% CL = 1.1, 6.9) for those with a birth injury and subsequent head injury, relative to those with neither a birth injury nor head injury. Our results provide only weak evidence in support of head injury as an etiologic agent for brain tumor occurrence in children, although most of our exposed group had only mild head injury.

Maternal consumption of cured meats and vitamins in relation to pediatric brain tumors

Brain tumors are the leading cause of death from childhood cancer, yet the causes of most of these tumors remain obscure. Few chemicals are effective in causing brain tumors experimentally after systemic administration of low doses; a notable exception is one group of N-nitroso compounds, the nitrosamides (in particular the nitrosoureas). Feeding pregnant animals nitrosamide precursors (e.g., sodium nitrite and an alkylamide such as ethylurea) causes a high incidence of nervous system tumors in offspring. This population-based epidemiological study was designed to test the hypothesis that maternal consumption during pregnancy of meats cured with sodium nitrite increases the risk of brain tumors among offspring. The intake of vitamins C and E blocks endogenous formation of nitroso compounds and was expected to be protective. Mothers of 540 children under age 20 with a primary brain tumor diagnosed during 1984-1991 and 801 control children in the same 19 counties on the U.S. West Coast were interviewed. Risk increased with increasing frequency of eating processed meats [odds ratio (OR) = 2.1 for eating at least twice a day compared to not eating; 95% confidence interval (CI) = 1.3-3.2; P = 0.003). Risk also increased with increasing average daily grams of cured meats or mg of nitrite from cured meats (P for each <0.005) but not with nitrate from vegetables. Daily use of prenatal vitamins throughout the pregnancy decreased risk (OR = 0.54; CI = 0.39-0.75). Risk among mothers who consumed above the median level of nitrite from cured meat was greater if vitamins were not taken (OR = 2.4; CI = 1.4-3.6) than if they were (OR = 1.3). These effects were evident for each of three major histological types and across social classes, age groups, and geographic areas. This largest study to date of maternal diet and childhood brain tumors suggests that exposure during gestation to endogenously formed nitroso compounds may be associated with tumor occurrence. Laboratory exploration is needed to: (a) define dietary sources of exposure to alkylamides; (b) investigate the reactivity of nitrite in high concentration such as around bits of cured meats in the stomach after ingestion compared to nitrite in dilute solution; and (c) confirm that simultaneous ingestion of alkylamides and cured meats leads to the endogenous formation of nitrosamides.