Risk factors for meningiomas in men in Los Angeles County.

A case-control study among men in Los Angeles County was conducted to investigate further the causes of intracranial meningiomas. Meningioma patients and a neighbor of each one were interviewed about past experiences that might be associated with tumor development. Analysis of information from the 105 matched pairs showed an association with meningioma occurrence for various factors relating to head trauma and head X-rays: 1) ever boxed as a sport [odds ratio (OR) = 2.0, P = 0.03], 2) had a serious head injury (OR = 1.9, P = 0.01), and 3) had X-ray treatment to the head before 20 years of age and/or had five or more full mouth dental X-ray series before 1945 (OR = 3.5, P = 0.02). Of the 105 subjects, 72 (69%) had a history of exposure to at least one of these factors.

Case-control study of intracranial meningiomas in women in Los Angeles County, California.

A case-control study was conducted among women in Los Angeles County to investigate possible causes of intracranial meningiomas. Questionnaires sought information from patients and from a neighbor of each one on characteristics and past experiences that might be associated with the development of this disease. Information was obtained on 188 matched patient-neighbor pairs. Three primary factors appeared to be associated with meningioma occurrence: 1) a history of head trauma (odds ratio = 2.0, P = 0.01), 2) consumption of certain cured meats (odds ratio = 2.8, P less than 0.01), and 3) exposure to medical and dental diagnostic X-rays to the head. For diagnostic X-rays, the strongest association was with early exposure (less than 20 yr old) to full-mouth dental X-ray series (odds ratio = 4.0, P less than 0.01).

Risk factors for gliomas and meningiomas in males in Los Angeles County.

Detailed job histories and information about other suspected risk factors were obtained during interviews with 272 men aged 25-69 with a primary brain tumor first diagnosed during 1980-1984 and with 272 individually matched neighbor controls. Separate analyses were conducted for the 202 glioma pairs and the 70 meningioma pairs. Meningioma, but not glioma, was related to having a serious head injury 20 or more years before diagnosis [odds ratio (OR) = 2.3; 95% confidence interval (CI) = 1.1-5.4], and a clear dose-response effect was observed relating meningioma risk to number of serious head injuries (P for trend = 0.01; OR for greater than or equal to 3 injuries = 6.2; CI = 1.2-31.7). Frequency of full-mouth dental X-ray examinations after age 25 related to both glioma (P for trend = 0.04) and meningioma risk (P for trend = 0.06). Glioma, but not meningioma risk, related to duration of prior employment in jobs likely to involve high exposure to electric and magnetic fields (P for trend = 0.05). This risk was greatest for astrocytoma (OR for employment in such jobs for greater than 5 years = 4.3; CI = 1.2-15.6). More glioma cases had worked in the rubber industry (discordant pairs 6/1) and more worked in hot processes using plastics (9/1). More meningioma cases had jobs that involved exposure to metal dusts and fumes (discordant pairs 13/5), and six of these cases and two controls worked as machinists. Finally, there was a protective effect among glioma pairs relating to frequency of use of vitamin C and other vitamin supplements (P for trend = 0.004); the OR for use at least twice a day was 0.4 (CI = 0.2-0.8).

Occupational differences in rates of lung cancer.

Lung cancer rates in Los Angeles County were reviewed for different occupations and industries. Employment groups found to be at excess risk who have not been previously implicated included roofers, dental lab technicians, decorators, nonautomotive mechanics, photoengravers, clothing ironers, electricians, bar and restaurant managers, janitors: and workers in the radio-TV brooad-casting, dairy, leather, food and drink, bakery, and auto repair industries. Mo lung cancer in Los Angeles County had exposure to asbestos, polycyclic aromatic hydrocarbon compounds (PAH), or both.

Medical and dental x rays as risk factors for recently diagnosed tumors of the head.

We used epidemiologic data on 2 tumor sites, the intracranial meninges and the parotid gland, to evaluate the importance of medical and dental x rays as risk factors for radiogenic tumors of the head diagnosed among residents of Los Angeles County in recent years. Exposures to x-ray treatment to the head and to full-mouth dental x-ray series before 1960 appear to be risk factors for both meningiomas and parotid tumors. Evidence from both descriptive and analytic studies suggests that the female over male excess of meningiomas, which is greatest from ages 25 to 54 years, may be partially explained by the excess exposure of young women to dental x rays. Study participants' ability to recall diagnostic x rays accurately is also evaluated by our comparisons of interview data to those available from dental charts. Recall of these events appears to be unbiased and accurate enough to justify the use of interview data in investigations of these risk factors.

Descriptive epidemiology of cancers of the upper respiratory tract in Los Angeles.

The descriptive epidemiology of cancer of three upper respiratory tract sites (lip; mouth and pharynx, excluding nasopharynx; and nose, sinus and nasopharynx) was explored using data from 1972-1976 from the population-based cancer registry covering Los Angeles County, California. In addition, the proportion of Los Angeles cases at each site which are explained by tobacco use was estimated using attributable risks calculated from previously published case-control studies. Causes of nontobacco-related cases are considered. Lip cancer was found to be a disease predominantly of white males with a male/female ratio of 9.8 for the lower lip and of 1.0 for the upper lip. Tobacco use is responsible for 60% of male lip cancers, and incidence rates of lip cancer after subtraction of the proportion of the incidence due to tobacco use were more than three times greater in men than in women. A hypothesis is proposed that an important etiologic factor is exposure to sun, wind and cold which results in chapping; this exposure is most intense for the lower lip; and the use of lip coverings in women protects their lips both from the sun and from chapping. Cigarette smoking was responsible for 51% of mouth and pharynx cancer in men and women in Los Angeles County, and after subtraction of the proportion of the incidence due to smoking, rates in men and women were similar. Factors such as poor dentition and nutritional deficiencies may help explain demographic characteristics such as the higher rates of mouth and pharynx cancer among men and women in the lower social classes and the secular decline in incidence rates. Cancers of the nose, sinus and nasopharynx were found to occur among workers in a wide range of occupations and industries which involved inhalation of dust, fumes and vapors. High incidence rates of nasopharynx cancer were observed among Chinese in Los Angeles and high rates of sinus cancer among Spanish-surnamed residents. Cancers at these sites appear to be related to the action of carcinogens on tissue chronically irritated by repeated upper respiratory infections or allergic responses. In addition racial differences in the physical structure of the nasal passage may influence where inhaled particles are deposited.

A dental x-ray validation study. Comparison of information from patient interviews and dental charts.

Information was collected from dentists of a subset of participants in a case-control interview study conducted in Los Angeles County, California, in August 1980-August 1981 to evaluate the relationship of dental x-rays to tumors of the parotid gland. Complete dental charts were available from 142 dentists of 84 cases and from 130 dentists of 79 controls. Analysis of data from these interview-chart comparisons indicates that recall appears to be unbiased since the measures of agreement between interview and dental chart data are similar for cases and controls. The authors further conclude that interview data alone may be used for case-control comparisons of dental x-ray exposure and would, because of unbiased misclassification, tend to underestimate the relative risks.