Background: Components of the metabolic syndrome (MetS), such as elevated fasting glucose levels and abdominal obesity, have been suggested as potential risk factors for pancreatic cancer. However, data are still insufficient to assure the influence of MetS on incident pancreatic cancer. The objective of the current study was to investigate the association between MetS, metabolic components, and the risk of pancreatic cancer. Methods: In the Korea National Health Information Database, 223,138 individuals who were without pancreatic cancer in 2009 were enrolled and followed until 2013. They were categorized into 4 groups according to the number of baseline metabolic components (0, 1, 2, 3, and 4‐5). A multivariate Cox proportional hazard model was used to calculate the adjusted hazard ratios (HRs) and 95% CIs for incident pancreatic cancer according to the presence of MetS and the number of metabolic components. In addition, the risk of pancreatic cancer was evaluated in individuals who had a single metabolic component. Results: The presence of MetS was significantly associated with incident pancreatic cancer (adjusted HR, 1.47; 95% CI, 1.19‐1.81). The group with 4 or 5 baseline metabolic components had a higher risk of pancreatic cancer than the other groups (0 components: reference category; 1 component: adjusted HR, 0.94 [95% CI, 0.61‐1.45]; 2 components: adjusted HR, 1.03 [95% CI, 0.68‐1.56]; 3 components: adjusted HR, 1.35 [95% CI, 0.89‐2.04]; 4‐5 components: adjusted HR, 1.64 [95% CI, 1.06‐2.51]). Regarding associations between the individual metabolic components and pancreatic cancer, no metabolic component alone had a statistically significant association with pancreatic cancer. Conclusions: MetS is a potential risk factor for pancreatic cancer. The presence of ≥4 metabolic components leads to a higher risk of pancreatic cancer even within categories of the MetS.

Background: It has often been reported that thyroid-specific autoimmune diseases, such as Hashimoto's thyroiditis and Graves’ disease, could increase the risk of thyroid cancer, but the association between other autoimmune diseases beyond thyroid and thyroid cancer has not been well investigated. This study aimed to examine the risk of thyroid cancer in patients with 8 autoimmune diseases compared with those without autoimmune diseases. Methods: This nationwide retrospective matched cohort study was conducted to investigate the relationship of 8 autoimmune diseases (Hashimoto's thyroiditis, Graves’ disease, type 1 diabetes mellitus, Sjogren’s disease, inflammatory bowel disease, vitiligo, systemic lupus erythematosus, rheumatoid arthritis) with the risk of incident thyroid cancer using the National Health Insurance Service- National Sample Cohort. The Cox-proportional hazard model was used to estimate the adjusted hazard ratio (HR) and 95% confidence intervals (95% CI) for thyroid cancer in relation to each of autoimmune disease compared with control group without autoimmune disease. Results: During the average follow-up of 9.49 years, 138 thyroid cancer cases were newly developed in control group and 268 cases were occurred in group with 8 autoimmune diseases. For all of study participants, the risk of thyroid cancer was significantly increased in patients with Hashimoto’s thyroiditis (HR=2.10 [1.57 – 2.81]), Graves’ disease (HR=2.67 [1.99 – 3.62]), inflammatory bowel disease (HR=2.06 [1.50 – 2.83]), vitiligo (HR=1.71 [1.13 – 2.59]), rheumatoid arthritis (HR=1.76 [1.07 – 2.90]), and total of 8 autoimmune diseases (HR=1.97 [1.60 – 2.42]) compared with control group without autoimmune diseases. When autoimmune diseases were divided into three types, thyroid-specific autoimmune diseases (HR=2.37 [1.85 – 3.03]) showed the strongest and significant association with thyroid cancer, followed by local autoimmune diseases (HR=1.83 [1.41 – 2.38]), and systemic autoimmune diseases (HR=1.77 [1.14 – 2.74]). Conclusions: Specific autoimmune diseases – especially for thyroid specific autoimmune disease, vitiligo, inflammatory bowel disease and rheumatoid arthritis – were associated with increased risk for thyroid cancer.

Evidence has suggested an increased risk of psychiatric manifestations following viral infections including coronavirus disease-2019 (COVID-19). However, psychiatric adverse events (AEs) after COVID-19 vaccination, which were documented in case reports and case series, remain unclear. This study is aimed to investigate the psychiatric AEs after COVID-19 vaccination from a large population-based cohort in Seoul, South Korea. We recruited 50% of the Seoul-resident population randomly selected from the Korean National Health Insurance Service (KNHIS) claims database on 1, January, 2021. The included participants (n = 2,027,353) from the Korean National Health Insurance Service claims database were divided into two groups according to COVID-19 vaccination. The cumulative incidences per 10,000 of psychiatric AEs were assessed on one week, two weeks, one month, and three months after COVID-19 vaccination. Hazard ratios (HRs) and 95% Confidence interval (CIs) of psychiatric AEs were measured for the vaccinated population. The cumulative incidence of depression, anxiety, dissociative, stress-related, and somatoform disorders, sleep disorders, and sexual disorders at three months following COVID-19 vaccination were higher in the vaccination group than no vaccination group. However, schizophrenia and bipolar disorders showed lower cumulative incidence in the vaccination group than in the non-vaccinated group. Depression (HR [95% CI] = 1.683 [1.520–1.863]), anxiety, dissociative, stress-related, and somatoform disorders (HR [95% CI] = 1.439 [1.322–1.568]), and sleep disorders (HR [95% CI] = 1.934 [1.738–2.152]) showed increased risks after COVID-19 vaccination, whereas the risks of schizophrenia (HR [95% CI] = 0.231 [0.164–0.326]) and bipolar disorder (HR [95% CI] = 0.672 [0.470–0.962]). COVID-19 vaccination increased the risks of depression, anxiety, dissociative, stress-related, and somatoform disorders, and sleep disorders while reducing the risk of schizophrenia and bipolar disorder. Therefore, special cautions are necessary for administering additional COVID-19 vaccinations to populations vulnerable to psychiatric AEs.

Shim SY, et al. J Korean Med Sci. 2021 Mar;36(11):e81. https://doi.org/10.3346/jkms.2021.36.e81

Background: Preterm birth contributes to the morbidity and mortality of newborns and infants. Recent studies have shown that maternal exposure to particulate matter and extreme temperatures results in immune dysfunction, which can induce preterm birth. This study aimed to evaluate the association between fine particulate matter (PM_2.5) exposure, temperature, and preterm birth in Seoul, Republic of Korea. Methods: We used 2010–2016 birth data from Seoul, obtained from the Korea National Statistical Office Microdata. PM_2.5 concentration data from Seoul were generated through the Community Multiscale Air Quality (CMAQ) model. Seoul temperature data were collected from the Korea Meteorological Administration (KMA). The exposure period of PM_2.5 and temperature were divided into the first (TR1), second (TR2), and third (TR3) trimesters of pregnancy. The mean PM_2.5 concentration was used in units of ×10 µg/m³ and the mean temperature was divided into four categories based on quartiles. Logistic regression analyses were performed to evaluate the association between PM_2.5 exposure and preterm birth, as well as the combined effects of PM_2.5 exposure and temperature on preterm birth. Result: In a model that includes three trimesters of PM_2.5 and temperature data as exposures, which assumes an interaction between PM_2.5 and temperature in each trimester, the risk of preterm birth was positively associated with TR1 PM_2.5 exposure among pregnant women exposed to relatively low mean temperatures (<3.4 °C) during TR1 (OR 1.134, 95% CI 1.061–1.213, p < 0.001). Conclusions: When we assumed the interaction between PM_2.5 exposure and temperature exposure, PM_2.5 exposure during TR1 increased the risk of preterm birth among pregnant women exposed to low temperatures during TR1. Pregnant women should be aware of the risk associated with combined exposure to particulate matter and low temperatures during TR1 to prevent preterm birth.

The oncogenic potential of SARS-CoV-2 has been hypothetically proposed, but real-world data on COVID-19 infection and vaccination are insufficient. Therefore, this large-scale population-based retrospective study in Seoul, South Korea, aimed to estimate the cumulative incidences and subsequent risks of overall cancers 1 year after COVID-19 vaccination. Data from 8,407,849 individuals between 2021 and 2023 were obtained from the Korean National Health Insurance database. The participants were categorized into two groups based on their COVID-19 vaccination status. The risks for overall cancer were assessed using multivariable Cox proportional hazards models, and data were expressed as hazard ratios (HRs) and 95% confidence intervals (CIs). The HRs of thyroid (HR, 1.351; 95% CI, 1.206–1.514), gastric (HR, 1.335; 95% CI, 1.130–1.576), colorectal (HR, 1.283; 95% CI, 1.122–1.468), lung (HR, 1.533; 95% CI, 1.254–1.874), breast (HR, 1.197; 95% CI, 1.069–1.340), and prostate (HR, 1.687; 95% CI, 1.348–2.111) cancers significantly increased at 1 year post-vaccination. In terms of vaccine type, cDNA vaccines were associated with the increased risks of thyroid, gastric, colorectal, lung, and prostate cancers; mRNA vaccines were linked to the increased risks of thyroid, colorectal, lung, and breast cancers; and heterologous vaccination was related to the increased risks of thyroid and breast cancers. Given the observed associations between COVID-19 vaccination and cancer incidence by age, sex, and vaccine type, further research is needed to determine whether specific vaccination strategies may be optimal for populations in need of COVID-19 vaccination.