Olof Nyrén

Physical activity and body mass index (BMI) are involved in prostate cancer etiology; possible biologic mechanisms include their effects on hormonal levels. Our aim was to investigate the relationship between physical activity, obesity, and prostate cancer. We followed a cohort of 13,109 Swedish men for 13 years and investigated the association of self-reported physical activity and BMI at baseline with prostate cancer incidence. We further analyzed whether BMI could modulate effects of physical activity. Occupational, recreational, and total physical activity were analyzed in relation to overall, localized, and advanced prostate cancer. During the study follow-up, we observed a total of 904 cases of prostate cancer (429 localized, 407 advanced, and 68 unclassified). High levels of occupational physical activity were associated with a nonsignificantly decreased risk of overall (HR 0.81, 95 % CI 0.61–1.07), localized (HR 0.75, 95 % CI 0.51–1.12), and advanced (HR 0.85, 95 % CI 0.55–1.31) prostate cancer. We found no association between high BMI and risk of prostate cancer incidence: We observed, however, a significant interaction between BMI and leisure physical activity. No association was confirmed between total physical activity and localized or advanced prostate cancer. The highest, relative to the lowest, level of occupational physical activity tended to be linked to a lower risk of prostate cancer, with a suggested dose–response relationship. We found no association between high BMI and risk of prostate cancer incidence; however, our analyses suggested an interaction between BMI and physical activity during recreational time that merits further investigation in future studies.

Frequent hand-washing is standard advice for avoidance of respiratory tract infections, but the evidence for a preventive effect in a general community setting is sparse. We therefore set out to quantify, in a population-based adult general population cohort, the possible protection against acute respiratory tract infections (ARIs) conferred by a person’s self-perceived hand-washing frequency. During the pandemic influenza season from September 2009 through May 2010, a cohort of 4365 adult residents of Stockholm County, Sweden, reported respiratory illnesses in real-time. A questionnaire about typical contact and hand-washing behaviour was administered at the end of the period (response rate 70%). There was no significant decrease in ARI rates among adults with increased daily hand-washing frequency: Compared to 2–4 times/day, 5–9 times was associated with an adjusted ARI rate ratio (RR) of 1.08 (95% confidence interval [CI] 0.87-1.33), 10–19 times with RR = 1.22 (CI 0.97-1.53), and ≥20 times with RR = 1.03 (CI 0.81-1.32). A similar lack of effect was seen for influenza-like illness, and in all investigated subgroups. We found no clear effect modification by contact behaviour. Health care workers exhibited rate ratio point estimates below unity, but no dose-risk trend. Our results suggest that increases in what adult laymen perceive as being adequate hand-washing may not significantly reduce the risk of ARIs. This might have implications for the design of public health campaigns in the face of threatening outbreaks of respiratory infections. However, the generalizability of our results to non-pandemic circumstances should be further explored.

In the meta-analysis of pancreatic cancer case–control studies reported by Bertuccio et al. [1], the authors found no association between use of smokeless tobacco (ST) and risk of pancreatic cancer. This finding contradicts two large cohort studies from northern Europe [2, 3]. The authors speculate about possible differences in ST products but emphasise as the most likely explanation for the discrepancy that the case–control studies, as opposed to the cohort studies, adjusted for major confounding factors, including ethnicity, education, body mass index (BMI), diabetes and alcohol consumption. The results have prompted a proponent for ST to exclaim “ … almost significant for a PROTECTIVE EFFECT” and “ … directly addresses a persistent question about the integrity of previous studies” (http://rodutobaccotruth.blogspot.com/). Therefore, we feel obliged to comment on the authors’ interpretation.

BACKGROUND: Transfusion safety rests heavily on the health of blood donors. Although they are perceived as being healthier than average, little is known about their long-term disease patterns and to which extent the blood banks' continuous efforts to optimize donor selection has resulted in improvements. Mortality and cancer incidence among blood donors in Sweden and Denmark was investigated. STUDY DESIGN AND METHODS: All computerized blood bank databases were compiled into one database, which was linked to national population and health data registers. With a retrospective cohort study design, 1,110,329 blood donors were followed for up to 35 years from first computer-registered blood donation to death, emigration, or December 31, 2002. Standardized mortality and incidence ratios expressed relative risk of death and cancer comparing blood donors to the general population. RESULTS: Blood donors had an overall mortality 30 percent lower (99% confidence interval [CI] 29%-31%) and cancer incidence 4 percent lower (99% CI 2%-5%) than the background population. Mortality rates and cancer incidence were lowest for outcomes that are recognized as being related to lifestyle factors such as smoking or to the selection criteria for blood donation. Blood donors recruited in more recent years exhibited a lower relative mortality than those who started earlier. CONCLUSION: Blood donors enjoy better than average health. Explicit and informal requirements for blood donation in Scandinavia, although mostly of a simple nature, have successfully refined the selection of a particularly healthy subpopulation.

Background and Objectives  Even with appropriate donor deferrals and advanced screening tests, the risk of disease transmission through blood transfusion cannot be completely disregarded. Efficient monitoring of possible disease transmission between blood donors and recipients should be an important component of a comprehensive haemovigilance system.Materials and Methods  We assembled the Scandinavian Donations and Transfusions (SCANDAT) database, with data on virtually all blood donors and recipients who have been registered at least once in any of the computerized local blood bank databases in Sweden and Denmark since the start of computerized registration in 1966. The records of these individuals, with their entire computerized donation and/or transfusion histories and all donor‐component‐recipient connections, were linked to nationwide population and health registers to attain essentially complete follow‐up for up to 36 years regarding reproduction, hospital morbidity, cancer, and death.Results  After data cleaning, the database contained 1 134 290 blood donors who contributed 15 091 280 records of donations and 1 311 079 recipients who received 11 693 844 transfusions. The data quality in the existing data sources was satisfactory. From the data obtained from local blood banks, 4·6%, 1·6%, and 6·4% of the person, donation, and transfusion records, respectively, had to be discarded after review of the legitimacy of recorded values, and comparisons with independent, external databases.Conclusion  It is possible to use existing computerized data, collected in routine health care, in haemovigilance systems for monitoring long‐term outcome and disease concordance in blood donors and transfusion recipients.