Incidence and survival of brain tumors: a population-based study.

Since 1976 the Lombardy Cancer Registry (RTL) has recorded all malignant tumors and the benign tumors of the nervous system, bladder and liver occurring in the Varese province. The aims of this report are: to describe age-specific incidence rates of the different oncotypes of primary nervous system tumors (PNSTs) and to analyze the duration of survival of the patients according to the histotype of the neoplasm. From 1976 to 1981, the RTL recorded 498 PNST: 213 tumors of glial origin, 132 tumors of mesodermal tissues, 15 tumors of multipotential cell origin, 37 tumors of nerve roots, 8 of vascular origin, and 54 PNST in which the histotype was not specified. For tumors of glial origin, the 60-69 year age class showed the highest incidence rate: 16 per 100,000/year. The incidence rate of tumors of mesodermal tissues reached the maximum value of 7.9 per 100,000/year in the age group of 75 years and over. Tumors of multipotential cell origin had a maximum incidence of 2.2 in the 60-69 year age class. The probability of survival at 5 years after diagnosis was computed by the method of Kaplan and Meier, and the log rank procedure was used to test statistical differences among survivors. Tumors of glial origin, excluding ependymomas and papillomas of choroid plexus, had a 5-year survival probability of 14%. Age (categorized in less than or equal to 50 and greater than 50 years) and histologic grade (grades I + II and grades III + IV) were analyzed as prognostic factors for tumors of glial origin: a younger age was the most predictive prognostic factor in grade I + II tumors (probability of survival = 53% in the group less than or equal to 50 years vs 0 in the group greater than 50 years; p less than 0.005). In the less differentiated tumors there were no differences between the two age groups. Patients with tumors of mesodermal tissues had a 5-year probability of survival of 83%. Subjects younger than 50 years had a probability of survival of 95%, whereas older patients had a probability of 79%. For the other oncotypes, the 5-year survival probability was: 50% for tumors of multipotential cell origin, 63% for ependymomas and papillomas of the choroid plexus, 64% for tumors of vascular derivation, and 21% for PNST with not specified histotype.

Gliomas and occupational exposure to carcinogens: case-control study.

Patients with gliomas of the central nervous system hospitalized during the period January 1979--March 1980 at the Neurological Institute C. Besta of Milan were compared with controls admitted to the Institute in the same period for nonneoplastic neurologic diseases or benign tumors. The comparison was based on occupational history, smoking habits, and alcohol consumption. Two analyses were carried out: the first by case-control pairs matched for age, sex, and residence; the second by age, sex, and residence stratification. Patients with glioma were more likely than controls to have worked in agricultural activities and showed a relative risk of 5.0 (p = 0.043) in the matched analysis and 1.9 (p = 0.113) in the analysis by stratification. This high risk was confined to those who performed agricultural work after 1960, suggesting a possible etiologic role of exposure to organic pesticides, fertilizers, and herbicides, which have only recently been commonly used in Italy. No significant difference was observed between cases and controls in regard to other analyzed occupations and habits.

Electrophysiological study of subjects occupationally exposed to lead and with low levels of lead poisoning.

The relationship between the length of exposure to lead, blood lead level (PbB), and peripheral nerve damage in a population occupationally exposed to low lead levels was evaluated. Sixty-two foundry workers were studied whose length of exposure ranged from 5 months to 10 a; their mean PbB in the last 2 a had not exceeded 50 microgram/100 ml (2.4 mumol/l). The referents were 27 hospital employees, of comparable ages, not occupationally exposed to lead. The electrophysiological examination consisted of the determination of the motor conduction velocity (MCV) of the median, and peroneal nerves, sensory conduction velocity (SCV) of the median and sural nerves, and the latency of the T and H reflexes. The mean MCV, SCV and the amplitude of the sensory action potential (SAP) of the median nerve were significantly lower in the group of exposed workers than in the reference group. When the exposed subjects were divided into three groups according to length of exposure, no difference was observed between the three groups. When they were divided into different groups according to the maximum PbB (max PbB) value, the observed differences with respect to the reference groups were already present in those with a max PbB of less than 50 microgram/100 ml (less than 2.4 mumol/l), but were more evident in the subjects with a max PbB of greater than 70 microgram/100 ml (greater than 3.4 mumol/l). Within the group of subjects with a max PbB of 50-69 microgram/100 ml (2.4-3.3 mumol/l), the differences with respect to the reference values were more evident for subjects with a short length of exposure (less than 2 a). The MCV of the median nerve correlated with the time since the PbB exceeded 50 microgram/100 ml (2.4 mumol/l). In conclusion, the electrophysiological changes observed in lead-exposed subjects do not seem correlated with the length of exposure. Such alterations seem more evident in those subjects whose PbB has been greater than 70 microgram/100 ml (3.4 mumol/l) at least once during the preceding 2 a and in those subjects who, at the time of the neurophysiological examination, have a PbB greater than 50 microgram/100 ml (2.4 mumol/l). The apparently greater sensitivity to lead in new employees, compared to workers with a longer exposure time, remains to be clarified.