A nested case-control study of radiation exposure and brain cancer incidence in the United States Air Force

A nested case-control study design was used to investigate the relationship between radiation exposure and brain cancer risk in the United States Air Force (USAF). The cohort consisted of approximately 880,000 men with at least 1 year of service between 1970 and 1989. Two hundred and thirty cases were identified from hospital discharge records with a diagnosis of primary malignant brain tumor (International Classification of Diseases, 9th revision, code 191). Four controls were exactly matched with each case on year of age and race using incidence density sampling. Potential career summary extremely low frequency (ELF) and microwave-radiofrequency (MWRF) radiation exposures were based upon the duration in each occupation and an intensity score assigned by an expert panel. Ionizing radiation (IR) exposures were obtained from personal dosimetry records.^ Relative to the unexposed, the overall age-race adjusted odds ratio (OR) for ELF exposure was 1.39, 95 percent confidence interval (CI) 1.03-1.88. A dose-response was not evident. The same was true for MWRF, although the OR = 1.59, with 95 percent CI 1.18-2.16. Excess risk was not found for IR exposure (OR = 0.66, 45 percent CI 0.26-1.72).^ Increasing socioeconomic status (SES), as identified by military pay grade, was associated with elevated brain tumor risk (officer vs. enlisted personnel age-race adjusted OR = 2.11, 95 percent CI 1.98-3.01, and senior officers vs. all others age-race adjusted OR = 3.30, 95 percent CI 2.0-5.46). SES proved to be an important confounder of the brain tumor risk associated with ELF and MWRF exposure. For ELF, the age-race-SES adjusted OR = 1.28, 95 percent CI 0.94-1.74, and for MWRF, the age-race-SES adjusted OR = 1.39, 95 percent CI 1.01-1.90.^ These results indicate that employment in Air Force occupations with potential electromagnetic field exposures is weakly, though not significantly, associated with increased risk for brain tumors. SES appeared to be the most consistent brain tumor risk factor in the USAF cohort. Other investigators have suggested that an association between brain tumor risk and SES may arise from differential access to medical care. However, in the USAF cohort health care is universally available. This study suggests that some factor other than access to medical care must underlie the association between SES and brain tumor risk. ^

Correlates of post-diagnosis weight management among female breast cancer survivors: An Internet survey

Objective. Weight gain after cancer treatment is associated with breast cancer recurrence. In order to prolong cancer-free survivorship, interventions to manage post-diagnosis weight are sometimes conducted. However, little is known about what factors are associated with weight management behaviors among cancer survivors. In this study, we examined associations of demographic, clinical, and psychosocial variables with weight management behaviors in female breast cancer survivors. We also examined whether knowledge about post-diagnosis weight gain and its risk is associated with weight management behaviors. ^ Methods. 251 female breast cancer survivors completed an internet survey. They reported current performance of three weight management behaviors (general weight management, physical activity, and healthy diet). We also measured attitude, elf-efficacy, knowledge and social support regarding these behaviors along with demographic and clinical characteristics. ^ Results. Multiple regression models for the weight management behaviors explained 17% of the variance in general weight management, 45% in physical activity and 34% in healthy dieting. The models had 9–14 predictor variables which differed in each model. The variables associated with all three behaviors were social support and self-efficacy. Self-efficacy showed the strongest contribution in all models. The knowledge about weight gain and its risks was not associated with any weight management behaviors. However, women who obtained the knowledge during cancer treatment were more likely to engage in physical activity and healthy dieting. ^ Conclusions. The findings suggest that an intervention designed to increase their self-efficacy to manage weight, to be physically active, to eat healthy will effectively promote survivors to engage in these behaviors. Knowledge may motivate women to manage post-diagnosis weight about risk if information is provided during cancer treatment.^