Key Points Question Is the interaction between mammographic breast density and overweight or obesity associated with breast cancer risk, and if so, does any association vary according to menopausal status? Findings In a cohort study of 3 248 941 premenopausal and 4 373 473 postmenopausal women aged 40 years or older screened for breast cancer, a positive additive interaction between high breast density and high body mass index was associated with an increased risk of breast cancer, especially among women in the postmenopausal period. Meaning This study suggests that women with overweight or obesity and dense breast tissue might benefit from tailored breast cancer screening strategies; these 2 factors should be incorporated into risk stratification in population-based breast cancer screening.

Background and Objectives：Laboratory research was carried out to investigate the teratogenic effect of X-ray on chick embryos, especially with regard to cardiovascular malformation. Materials and Methods：The chick embryos, 242, 242 and 215 eggs, were irradiated with X-ray at the dose of 500, 750 and 1000 cGy, respectively, during the incubation period between 0 and 9 days. A control group of 90 eggs received no irradiation. After 2 weeks of incubation, the embryos were sacrificed and examined. Results：The survival rate of irradiated group was significantly lower than that of control group (62.5 vs. 87.8%, p<0.0001). The incidence rate of cardiovascular malformation was significantly higher in the irradiated than the control group (16.2 vs. 2.5%, p<0.005). The rate of cardiovascular malformation in the irradiated group increased from 9.4% with 500 cGy to 24.5% with 1000 cGy (p<0.05). There were a total of 33 cases of cardiac malformation, of which 24 were ventricular septal defects and 9 were complex congenital heart diseases. The higher the administered dose of radiation, the higher the observed incidence rate of cardiac malformation and the more complex the cardiac anomaly. Also, the rates of exocardia, exencephaly, beak anomalies and anopia were all increased in the irradiated group. Con-clusion：X-ray irradiation of chick embryos increased the rates of death and cardiovascular malformation. The highest dose resulted in greater complexity of the cardiovascular malformation. (Korean Circulation J 2005; 35:402-410) KEY WORDS：X-rays；Chick embryo；Heart；Malformations.

Objectives: This study aimed to determine the association between metabolic syndrome (MetS) and the incidence of colorectal cancer (CRC) in Korean women with obesity.Methods: Cancer-free women (n=6 142 486) aged 40-79 years, who underwent National Health Insurance Service health examinations in 2009 and 2010 were included. The incidence of CRC was followed until 2018. The hazard ratio (HR) of MetS for the incidence of colon and rectal cancer was analyzed according to body mass index (BMI) categories, adjusting for confounders such as women’s reproductive factors. In addition, the heterogeneity of associations across BMI categories was assessed.Results: Women with MetS were at increased risk of colon and rectal cancer compared to women without MetS (HR, 1.20; 95% confidence interval [CI], 1.16 to 1.23 and HR,1.15; 95% CI, 1.11 to 1.20), respectively. The HR of MetS for colon cancer across BMI categories was 1.12 (95% CI, 1.06 to 1.19), 1.14 (95% CI, 1.08 to 1.20), and 1.16 (95% CI, 1.12 to 1.21) in women with BMIs <23.0 kg/m², 23.0-24.9 kg/m², and ≥25.0 kg/m², respectively. The HR of MetS for rectal cancer across corresponding BMI categories was 1.16 (95% CI, 1.06 to 1.26), 1.14 (95% CI, 1.05 to 1.23), and 1.13 (95% CI, 1.06 to 1.20). The heterogeneity of associations across BMI categories was not significant in either colon or rectal cancer (<i>p</i>=0.587 for colon cancer and <i>p</i>=0.927 for rectal cancer).Conclusions: Women with MetS were at increased risk of colon and rectal cancer. Clinical and public health strategies should be considered for primary CRC prevention with an emphasis on improving women’s metabolic health across all BMI groups.

In 1945, atomic bombs were dropped on Hiroshima and Nagasaki. Approximately 70 000 Koreans are estimated to have been exposed to radiation from atomic bombs at that time. After Korea’s Liberation Day, approximately 23 000 of these people returned to Korea. To investigate the long-term health and hereditary effects of atomic bomb exposure on the offspring, cohort studies have been conducted on atomic bomb survivors in Japan. This study is an ongoing cohort study to determine the health status of Korean atomic bomb survivors and investigate whether any health effects were inherited by their offspring. Atomic bomb survivors are defined by the Special Act On the Support for Korean Atomic Bomb Victims, and their offspring are identified by participating atomic bomb survivors. As of 2024, we plan to recruit 1500 atomic bomb survivors and their offspring, including 200 trios with more than 300 people. Questionnaires regarding socio-demographic factors, health behaviors, past medical history, laboratory tests, and pedigree information comprise the data collected to minimize survival bias. For the 200 trios, whole-genome analysis is planned to identify <i>de novo</i> mutations in atomic bomb survivors and to compare the prevalence of <i>de novo</i> mutations with trios in the general population. Active follow-up based on telephone surveys and passive follow-up with linkage to the Korean Red Cross, National Health Insurance Service, death registry, and Korea Central Cancer Registry data are ongoing. By combining pedigree information with the findings of trio-based whole-genome analysis, the results will elucidate the hereditary health effects of atomic bomb exposure.

Background Atomic bombs dropped on Hiroshima and Nagasaki in Japan in August 1945 were estimated to have killed approximately 70,000 Koreans. In Japan, studies on the health status and mortality of atomic bomb survivors compared with the non-exposed population have been conducted. However, there have been no studies related to the mortality of Korean atomic bomb survivors. Therefore, we aimed to study the cause of death of atomic bomb survivors compared to that of the general population. Methods Of 2,299 atomic bomb survivors registered with the Korean Red Cross, 2,176 were included in the study. In the general population, the number of deaths by age group was calculated from 1992 to 2019, and 6,377,781 individuals were assessed. Causes of death were categorized according to the Korean Standard Classification of Diseases. To compare the proportional mortality between the two groups, the P value for the ratio test was confirmed, and the Cochran-Armitage trend test and χ 2 test were performed to determine the cause of death according to the distance from the hypocenter. Results Diseases of the circulatory system were the most common cause of death (25.4%), followed by neoplasms (25.1%) and diseases of the respiratory system (10.6%) in atomic bomb survivors who died between 1992 and 2019. The proportional mortality associated with respiratory diseases, nervous system diseases, and other diseases among atomic bomb survivors was higher than that of the general population. Of the dead people between 1992 and 2019, the age at death of survivors who were exposed at a close distance was younger than those who were exposed at a greater distance. Conclusion Overall, proportional mortality of respiratory diseases and nervous system diseases was high in atomic bomb survivors, compared with the general population. Further studies on the health status of Korean atomic bomb survivors are needed.