While early-life exposure to stress has been associated with subsequent psychiatric and cardiovascular morbidity, little is known regarding its potential role in cancer development. We hypothesized that severe emotional stress, such as the loss of a parent through death during childhood, may increase the risk of cancer in early life.
Based on the Swedish Multi-Generation Register, we identified a cohort of 4,219,691 individuals who had both parents identifiable in the same register and followed the cohort from birth to the age of 40 years between 1961 and 2006. Through information retrieved from the Swedish Causes of Death and Cancer Registers, we ascertained death among the parents and cancer diagnosis among the cohort individuals. We used Poisson regression to calculate the relative risks (RRs) and 95 % confidence intervals (CIs).
Parental death was not associated with total cancer risk. However, parental death during childhood was associated with a higher risk of human papillomavirus (HPV) infection-related cancers (RR 1.4; 95 % CI 1.2-1.7), and loss during early adulthood (>18 years) entailed a higher risk of cancers of the stomach (RR 1.8; 95 % CI 1.3-2.6), lung (RR 1.7; 95 % CI 1.1-2.4), rectum (RR 1.4; 95 % CI 1.0-2.0), and breast (RR 1.1; 95 % CI 1.0-1.3). A significant association was observed for pancreatic cancer for both loss during childhood (RR 2.6; 95 % CI 1.6-4.2) and afterward (RR 2.8; 95 % CI 1.9-4.3).
Our results suggest that severe psychological stress in early life may be associated with premature development of certain malignancies, particularly cancers related to smoking and HPV infection.
To investigate whether dog and cat owners and their pets share a risk of developing diabetes.
Register based longitudinal study, Sweden.
208?980 owner-dog pairs and 123?566 owner-cat pairs identified during a baseline assessment period (1 January 2004 to 31 December 2006).
Type 2 diabetes events in dog and cat owners and diabetes events in their pets, including date of diagnosis during the follow-up period (1 January 2007 to 31 December 2012). Owners with type 2 diabetes were identified by combining information from the National Patient Register, the Cause of Death Register, and the Swedish Prescribed Drug Register. Information on diabetes in the pets was extracted from veterinary care insurance data. Multi-state models were used to assess the hazard ratios with 95% confidence intervals and to adjust for possible shared risk factors, including personal and socioeconomic circumstances.
The incidence of type 2 diabetes during follow-up was 7.7 cases per 1000 person years at risk in dog owners and 7.9 cases per 1000 person years at risk in cat owners. The incidence of diabetes in the pets was 1.3 cases per 1000 dog years at risk and 2.2 cases per 1000 cat years at risk. The crude hazard ratio for type 2 diabetes in owners of a dog with diabetes compared with owners of a dog without diabetes was 1.38 (95% confidence interval 1.10 to 1.74), with a multivariable adjusted hazard ratio of 1.32 (1.04 to 1.68). Having an owner with type 2 diabetes was associated with an increased hazard of diabetes in the dog (crude hazard ratio 1.28, 1.01 to 1.63), which was attenuated after adjusting for owner's age, with the confidence interval crossing the null (1.11, 0.87 to 1.42). No association was found between type 2 diabetes in cat owners and diabetes in their cats (crude hazard ratio 0.99, 0.74 to 1.34, and 1.00, 0.78 to 1.28, respectively).
Data indicated that owners of a dog with diabetes were more likely to develop type 2 diabetes during follow-up than owners of a dog without diabetes. It is possible that dogs with diabetes could serve as a sentinel for shared diabetogenic health behaviours and environmental exposures.
Stress resilience is recognised as a determinant of both psychiatric and somatic health, but the potential link between stress resilience and cancer development has not been explored.
In this nationwide cohort study, we examined the association between stress resilience in adolescence and subsequent cancer risk. We identified a cohort of 284?257 Swedish men, born 1952-1956, who underwent compulsory military enlistment examinations including measures of psychological stress resilience (median age 18 years). The resulting score was categorised as low, moderate and high stress resilience. Individuals diagnosed with cancer during the follow-up time were identified through data linkage to the Swedish Cancer Register.
Lowest stress resilience, compared with the highest, was associated with increased risks of liver (HR: 4.73, 95% CI 2.73 to 8.19) and lung (HR: 2.75, 95%?CI 2.02 to 3.74) cancer after adjusting for markers of socioeconomic circumstances in childhood (p for trend