Physical activity and risk of lymphoma: a meta-analysis.

BACKGROUND: Physical activity has a protective effect on some types of cancer. The aim of the present meta-analysis was to explore the literature on the association between physical activity and risk of lymphoma. METHODS: A meta-analysis was conducted for cohort and case-control studies examining the association between self-reported physical activity and risk of lymphoma. Depending on statistical heterogeneity, a random or fixed effects model was used to estimate the summary OR and corresponding 95% confidence interval (CI). RESULTS: Seven case-control studies and 5 cohort studies were included. When data from both study designs were combined, no significant influence of physical activity on risk of lymphoma was found (pooled OR = 0.90; 95% CI: 0.79-1.02; P = 0.10). Subgroup analysis revealed a significant protective influence of physical activity on risk of lymphoma in case-control studies (pooled OR = 0.81; 95% CI: 0.68-0.96; P = 0.02). In contrast, cohort studies, which have a higher level of evidence than case-control studies, confirm the results of the primary meta-analysis (pooled OR = 1.02; 95% CI: 0.88-1.19; P = 0.76). A subsequent subgroup analysis found no significant differences between results for Hodgkin lymphoma and non-Hodgkin lymphoma (χ(2) = 0.16; P = 0.69), nor between results for recreational and occupational activities (χ(2) = 1.01; P = 0.31). CONCLUSIONS: Epidemiologic research indicates no significant influence of physical activity on risk of lymphoma. IMPACT: Future research should examine the association between sedentary behavior and risk of lymphoma and investigate the dose-response and timing effect of physical activity on risk of lymphoma.

Observations as to male fertility in the Flemish environment and health studies.

We report the observations made on 101 healthy non-smoking men aged 21-40 (50 from two industrial suburbs of the big city of Antwerp and 51 from Peer, a predominantly rural municipality with 14,622 inhabitants, 70 km east of Antwerp, chosen as the "control" area in spite of its intensive agriculture). Persons with known occupational exposures, persons working in a region with characteristics clearly different from the area of residence, and people commuting over long distances were excluded from the study. Sperm morphology was significantly worse in Peer than in Antwerp. Serum testosterone levels were significantly lower in Peer than in Antwerp. The proportions of men with very low and low serum testosterone levels, of men with very low and low spermatozoa concentrations and of men with very low and low percentages of spermatozoa with normal morphology, were all higher in Peer than in Antwerp. We speculate that both the lower testosterone concentrations and the poorer sperm quality are due to disturbance of the hypothalamic-pituitary-testicular function by hormone disrupters. Our data suggest that exposure to levels of environmental pollution which are widespread in developed nations, can have unfavourable effects on endocrine equilibrium and may disturb male fertiline disrupters.