Norie Sawada’s research while affiliated with National Cancer Center, Japan and other places

Background While the preventive effects of green tea and coffee on cognitive decline have been demonstrated, their long-term effects on cognition remain unclear. Objective This study aims to investigate the effect of green tea and coffee consumption in middle age on the prevention of dementia. Methods This population-based cohort study included 1155 participants (aged 44–66 in 1995). Participants’ consumption of green tea and coffee was assessed using questionnaires in 1995 and 2000. Their cognitive levels were neuropsychologically evaluated in 2025–2015. Logistic regression analyses were conducted with significant cognitive decline (defined as multi-domain cognitive decline and more severe conditions) as the dependent variable. Stratified analyses were also conducted by sex and age. Results Individuals who consumed 2–3 cups of green tea daily had a significantly reduced risk of cognitive decline (OR = 0.56, 95%CI: 0.35–0.91) after adjusting potential confounders. However, this effect was not significant with consumption of 4 or more cups. This protective effect was particularly observed in males (OR = 0.38, 95%CI: 0.19–0.76). A significant risk reduction was also observed in individuals consuming one or more cups of coffee daily (OR = 0.54, 95%CI: 0.34–0.84) in the older subjects (median age [53 years old] and older in 1995) in the same fully adjusted model, but not in the entire sample. Conclusions Our findings suggest that moderate green tea consumption in midlife may have a beneficial effect on preventing dementia, particularly in males. The effects of coffee consumption may be more advantageous for older individuals.

Background While previous literature suggests that multimorbidity is linked to a higher risk of mortality, evidence is scarce among individuals in middle adulthood. We aimed to examine the association between physical multimorbidity and all-cause mortality among individuals aged 40–64 years at baseline in Japan. Methods Data were obtained from two cohort studies, the Japan Public Health Center-based Prospective Study (JPHC) and the Japan Epidemiology Collaboration on Occupational Health Study (J-ECOH). The study participants were 144,774 individuals aged 40–64 years at baseline who were followed up for a maximum of 29 and 10 years in the JPHC and J-ECOH, respectively. Multimorbidity was defined as the presence of ≥ 2 of 10 morbidities or conditions based on self-reported information. A Cox proportional hazards model was used to examine the association in relation to all-cause mortality. We calculated pooled hazard ratios (HR) and corresponding 95% confidence intervals (CI) using a random-effects meta-analysis model. Cause-specific analysis was performed using the JPHC dataset, which provided a sufficient number of events for mortality due to physical disorders, mental disorders/suicide, and unintentional injuries. Results During a follow-up of 2,304,375 person-years in the JPHC and 311,637 person-years in the J-ECOH, 23,611 and 275 deaths were recorded, respectively. Participants with vs. without physical multimorbidity at baseline were more likely to die prematurely in both cohorts with a pooled HR of 1.61 (95%CI = 1.29–2.01). Cause-specific analyses among the JPHC participants revealed that physical multimorbidity at baseline was linked with mortality due to physical disorders, mortality due to mental disorders/suicide, and mortality due to unintentional injuries. Conclusions Physical multimorbidity in middle adulthood is associated with an increased risk of all-cause mortality in Japan.

Background There are scarce data on risk factors for epithelial ovarian cancer (EOC) in Asian populations. Our goal was to advance knowledge on reproductive -related risk factors for EOC in a large population of Asian women. Methods This study used pooled individual data from baseline questionnaires in 11 prospective cohorts (baseline years, 1958–2015) in the Asia Cohort Consortium. A Cox proportional hazards regression model was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) adjusting for age, parity and cohort. Results After a mean = 17.0 years (SD = 6.3) of follow-up, 674 incident invasive EOC cases were identified among 325,626 women. In multivariable adjusted models we observed an inverse association with parity (5+ children vs. 0, HR = 0.44, 95% CI = 0.28–0.68, Ptrend < 0.001), and a positive association with increasing menopausal age (55+ years vs. <45, HR = 1.77, 95% CI = 1.05–3.01, Ptrend = 0.02) for risk of all EOC. Conclusions In this large study of Asian women we identified an inverse association with parity and a positive association with higher menopausal age in relation to EOC risk. Further work is needed to understand EOC risk factors for rare histologic subtypes that occur more frequently in Asian populations.

Background Intake of branched-chain amino acids (BCAA) has been suggested to have a prophylactic effect against carcinogenesis in colorectal cancer (CRC). However, the possible effect of plasma BCAA concentration has not been fully evaluated. Methods We conducted a prospective case–control study within a cohort of four public health center areas for which blood sample and questionnaire data from a 5-year follow-up survey were available. We identified 360 newly diagnosed CRC cases during the follow-up period and selected two matched controls for each case. We estimated odds ratio (OR) and 95% confidence intervals (CI) for CRC using conditional logistic regression models adjusted for potential confounding factors. Results Increased plasma concentrations of BCAAs were not inversely associated with CRC risk after adjustment for potential confounders. Compared with the lowest quartile, ORs in the highest quartile of leucine, isoleucine, valine, and total BCAA were 0.74 (95% CI, 0.49–1.12), 0.85 (0.56–1.29), 0.75 (0.50–1.13), and 0.70 (0.47–1.05), respectively. After excluding cases diagnosed within the first 6 years of follow-up, total BCAA and leucine were significantly related to a decreased risk of CRC, with ORs in the highest quartile of total BCAA and leucine of 0.58 (0.35–0.96) and 0.56 (0.33–0.93), respectively. Conclusions We found no statistically significant inverse association between plasma BCAA concentrations and CRC risk in overall analyses, whereas on 6-year exclusion, total BCAA and leucine were associated with decreased CRC risk. Plasma BCAA concentrations may play a prophylactic role in colorectal carcinogenesis, and further investigation is warranted.

Background Although cigarette smoking and alcohol consumption are established causes of cancer, most cohort studies and meta-analyses have reported inverse associations with thyroid cancer risk. However, epidemiologic evidence for this possibility is limited in Asia, where thyroid cancer histologic type differs from the West. In this study, we examined the association between cigarette smoking or alcohol consumption and the risk of thyroid cancer in Japanese. Methods We analyzed data of 101,849 Japanese included in the Japan Public Health Center–Based Prospective Study. Cigarette smoking and alcohol consumption were assessed at baseline using a self-administered questionnaire. Cox proportional hazards regression models were used to estimate the HRs and 95% confidence intervals (CI). Results During a mean 18.7 years of follow-up, we identified 232 incident cases of thyroid cancer. The multivariable-adjusted HRs (95% CIs) for current cigarette smoking with ≥20 pack-years compared with never-smoking were 0.65 (0.39–1.06) and 0.45 (0.23–0.88), respectively, combined for both sexes. After detailed adjustment for cigarette smoking, compared with no current alcohol consumption, HRs (95% CIs) were 0.90 (0.61–1.33) for any current consumption and 0.81 (0.33–1.97) for ≥300 g ethanol/week consumption combined for both sexes. Conclusions We observed an inverse association between cigarette smoking and thyroid cancer in Japan. Although an inverse association between alcohol consumption and thyroid cancer is suggested, the CI was wide and included 1. Impact Cigarette smoking was shown to be potentially inversely associated with thyroid cancer in Japanese, providing insights into risk factors in Asians. Further studies with larger sample sizes are needed to verify these findings.