Posttraumatic Stress Disorder and Cancer Risk: A Nested Case-Control Study

A meta-analysis of the association between post-traumatic stress disorder and cancer risk

BACKGROUND

Several studies have investigated the link between post-traumatic stress disorder (PTSD) and cancer risk but reported mixed results. The objective of our study was to investigate the association between PTSD and cancer risk.

METHODS

Studies published in English about the relationship between PTSD and cancer incidence were systematically searched. We performed a meta-analysis to estimate the relative risks (RR) and 95% confidence intervals (CI) for cancer incidence.

RESULT

A total of 3,129 articles were screened. Finally, 8 articles and 11 studies were included in the meta-analysis. We found that PTSD was not associated with cancer risk compared with controls. For site-specific cancer, our results showed that women with PTSD were associated with higher risk of ovarian cancer than controls. However, PTSD was not associated with the risk of gastrointestinal cancer, breast cancer and lung cancer.

CONCLUSION

These analyzes based on studies published in English suggest that PTSD is associated with ovarian cancer risk, although the evidence base is very limited. Future studies are needed to investigate the mechanisms that PTSD diagnosis influenced cancer incidence depending on types of cancer.

Stress-related disorders and subsequent cancer risk and mortality: a population-based and sibling-controlled cohort study in Sweden

Prior research has suggested a potential role of psychological stress on cancer development while the role of familial factors on this association is underexplored. We conducted a nationwide cohort study including 167,836 individuals with a first-onset stress-related disorder (including post-traumatic stress disorder, acute stress reaction, adjustment disorder and other stress reactions) diagnosed between 1981 and 2016 in Sweden (i.e., exposed patients), 1,631,801 birth year- and sex-matched unexposed individuals, and 179,209 unaffected full siblings of the exposed patients. Cox models were used to estimate the hazard ratios (HRs) of newly diagnosed cancer and cancer-related death, beyond 1 year after diagnosis of stress-related disorders. We further examined the potential mediation roles of behavior-related morbidities in the associations of stress-related disorders with smoking or alcohol-related cancer incidence and mortality. We found modestly elevated risks of cancer incidence and mortality among exposed patients compared with matched unexposed individuals (incidence: HR = 1.03, 95% CI 1.01–1.06; mortality: HR = 1.13, 95% CI 1.07–1.18), while not when comparing with full siblings (incidence: HR = 1.03, 95% CI 0.99–1.08; mortality: HR = 1.09, 95% CI 1.00-1.19). Similarly, the suggested elevations in incidence and mortality of individual cancer sites (or groups) in the population-based comparison attenuated towards null in the between-sibling comparison. The risk elevations for smoking or alcohol-related cancers in the population-based comparison (incidence: HR = 1.18, 95% CI 1.11–1.24; mortality: HR = 1.20, 95% CI 1.12–1.29) were partially mediated by alcohol-related morbidities during follow-up. Collectively, our findings suggest that the association between stress-related disorders and cancer risk and mortality is largely explained by familial factors, including shared behavioral hazards.

Posttraumatic stress disorder and breast cancer: Risk factors and the role of inflammation and endocrine function

A breast cancer diagnosis can be a life-changing and stressful experience that can lead to chronic mental health conditions such as posttraumatic stress disorder (PTSD). Greater than one-third of patients initially diagnosed with PTSD after a diagnosis of breast cancer continue to have persistent or worsening PTSD symptoms after 4 years. An emerging body of literature has indicated several key environmental and biological risk factors for PTSD among survivors of breast cancer. Well-recognized risk factors include having a history of childhood trauma, being nonwhite, obesity, younger age at the time of diagnosis, diagnosis with a higher stage of breast cancer, and short time since treatment. Of the emerging risk factors related to fear circuitry in the brain, 2 pathways of particular importance are the stress-driven activation of inflammatory pathways and the long-term effect of antiendocrine therapies. These central and peripheral responses during and after stress exposure are important because increased fear and anxiety can lead to the maintenance of PTSD and worse patient outcomes. Given the poor outcomes associated with PTSD and the high prevalence of breast cancer in women, more research to identify those women at heightened risk of PTSD after breast cancer is warranted to reduce the number of diagnoses and lessen the negative impact of this chronic mental health condition.