Journal of Epidemiology
Online ISSN : 1349-9092
Print ISSN : 0917-5040
ISSN-L : 0917-5040
Volume 29, Issue 5
Displaying 1-5 of 5 articles from this issue
Original Article
  • Xuelian Yuan, Fang Yi, Can Hou, Hui Lee, Xiaorong Zhong, Ping Tao, Hui ...
    2019 Volume 29 Issue 5 Pages 173-179
    Published: May 05, 2019
    Released on J-STAGE: May 05, 2019
    Advance online publication: August 11, 2018
    Supplementary material

    Background: The association between induced abortion and birth control methods (including oral contraceptives and intrauterine devices) and breast cancer may vary among countries, due to the different usage and frequency of birth control methods and induced abortion among countries. A better understanding of this association may help in determining safer birth control methods for Chinese women.

    Methods: A case-control study was conducted with a total of 794 cases and 805 controls. Standardized questionnaires were used to collect information on demographic characteristics, exposure to induced abortion, birth control methods, and other risk factors for breast cancer. Multivariate logistic regression was conducted to explore the association between birth control methods and breast cancer.

    Results: Multivariate logistic regression analyses showed that having a history of medical abortions, ≥3 surgical abortions, or both medical and surgical abortions was associated with an increased risk of breast cancer in post-menopausal women (odds ratio [OR] 2.48; 95% confidence interval [CI], 1.14–5.40). Pre-menopausal women who had used intra-uterine devices (IUDs) for more than 20 years tended to have a lower breast cancer risk than other age-matched pre-menopausal women (OR 0.41; 95% CI, 0.25–0.68). Both pre-menopausal and post-menopausal women who had <20 years exposure to IUDs and those who had used two or more birth control methods (with the exception of women who used IUDs for more than 20 years) tended to have much higher breast cancer risk.

    Conclusion: The relationship between induced abortion and birth control methods and breast cancer was complex, though being exposed to induced abortion and two or more birth control methods in one’s lifetime appeared to be risk factors for breast cancer in Chinese women.

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  • Takeshi Makiuchi, Tomotaka Sobue, Tetsuhisa Kitamura, Norie Sawada, Mo ...
    2019 Volume 29 Issue 5 Pages 180-186
    Published: May 05, 2019
    Released on J-STAGE: May 05, 2019
    Advance online publication: May 11, 2018

    Background: Smoking and alcohol are established risk factors for several types of cancer, but the effects on biliary cancers, comprising biliary tract cancer (BTC) and intrahepatic bile duct cancer (IHBDC), have been inconclusive.

    Methods: In this population-based prospective cohort study in Japan, we investigated the association of smoking and alcohol consumption with the risks of BTC and its subtypes and IHBDC incidence in men and women. Furthermore, the association of smoking stratified by drinking status was investigated. The hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using the Cox proportional hazard model.

    Results: A total of 48,367 men and 54,776 women aged 40–69 years were enrolled from 1990 through 1994 and followed up for 846,417 person-years in men and 1,021,330 person-years in women until 2012, during which 246 BTC and 80 IHBDC male cases and 227 BTC and 60 IHBDC female cases were identified. In men, smoking was significantly associated with an increased risk of IHBDC (HR 2.25; 95% CI, 1.19–4.25 for current smokers with ≥30 pack-years compared with non-smokers), and the risk was enhanced among regular drinkers compared with non/occasional-drinkers (HR 3.48; 95% CI, 1.41–8.61). A non-significant increase of IHBDC risk associated with alcohol was observed. Neither smoking nor alcohol consumption was associated with BTC risk. In women, the association of smoking and alcohol consumption with IHBDC and BTC was unclear because current smokers and regular drinkers were very few.

    Conclusion: Our findings suggest that smoking increases IHBDC risk in men, especially among regular drinkers.

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  • Hyo Kyozuka, Keiya Fujimori, Mitsuaki Hosoya, Seiji Yasumura, Tadahiko ...
    2019 Volume 29 Issue 5 Pages 187-191
    Published: May 05, 2019
    Released on J-STAGE: May 05, 2019
    Advance online publication: August 04, 2018

    Background: In Japan, mean maternal age at first childbirth is increasing. The aim of this study was to investigate whether maternal age at the first childbirth is a risk factor for preterm birth (PTB), low birth weight (LBW), and small for gestational age (SGA).

    Methods: We used the results of Japan Environment and Children’s Study (JECS) who gave birth in 2011–2014. Cases of primiparous singleton pregnancies where the subject was ≥20 years and delivered after 22 weeks were included. All subjects were categorized into five groups according to maternal age: 20–24, 25–29, 30–34, 35–39, and ≥40 years. Adjusted odds ratios (aORs) for PTB (before 37 and 34 weeks), LBW (<2,500 g and <1,500 g), and SGA were calculated using a logistic regression model, with the 20–24-year age group as reference.

    Results: We analyzed 38,412 singleton primiparous pregnancies. The aORs of all outcomes increased in parallel with each maternal age group >30 years. The aORs of PTB before 37 and 34 weeks, LBW <2,500 g, LBW <1,500 g, and SGA in the 30–34-year age group were 1.39 (95% confidence interval [CI], 1.16–1.67), 2.23 (95% CI, 1.45–3.41), 1.34 (95% CI, 1.18–1.53), 2.30 (95% CI, 1.35–3.94), and 1.24 (95% CI, 1.05–1.46), respectively.

    Conclusion: The present study showed that higher maternal age (>30 years) at the first childbirth was an independent risk factor for PTB, LBW, and SGA.

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  • Ayaka Igarashi, Jun Aida, Toshimi Sairenchi, Toru Tsuboya, Kemmyo Sugi ...
    2019 Volume 29 Issue 5 Pages 192-196
    Published: May 05, 2019
    Released on J-STAGE: May 05, 2019
    Advance online publication: May 31, 2018

    Background: Annually, more than 1.2 million deaths due to road traffic accidents occur worldwide. Although previous studies have examined the association between cigarette smoking and injury death, the mortality outcome often included non-traffic accident-related deaths. This study aimed to examine the association between cigarette smoking and traffic accident death.

    Methods: We conducted a prospective cohort study using data from the Ibaraki Prefectural Health Study conducted from 1993 through 2013. The cohort included 97,078 adults (33,138 men and 63,940 women) living in Ibaraki Prefecture who were aged 40–79 years at an annual health checkup in 1993. We divided participants into four smoking status groups: non-smokers, ex-smokers, and current smokers who smoked <20 and ≥20 cigarettes per day. Hazard ratios (HRs) of traffic accident death were calculated using a Cox proportional hazards model.

    Results: During 20 years of follow-up, the average person-years of follow-up were 16.8 and 18.2 in men and women, respectively. Among men, after adjusting for age and alcohol intake, HRs for traffic accident death among current smokers of <20 cigarettes/day and ≥20 cigarettes/day compared to non-smokers were 1.32 (95% confidence interval [CI], 0.79–2.20) and 1.54 (95% CI, 0.99–2.39), respectively. In contrast, among women, we found no association between smoking status and traffic accident deaths.

    Conclusion: In this prospective cohort study, we found a positive association, though marginally significant, between smoking and traffic accident death among men in Japan. Among women, because of the smaller number of deaths among smokers, adequate estimation could not be obtained.

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  • Supot Kamsa-ard, Vor Luvira, Krittika Suwanrungruang, Siriporn Kamsa-a ...
    2019 Volume 29 Issue 5 Pages 197-204
    Published: May 05, 2019
    Released on J-STAGE: May 05, 2019
    Advance online publication: August 04, 2018

    Background: Cholangiocarcinoma (CCA) is a common malignancy in northeastern Thailand. Over the last 4 decades, several policies have been implemented for its prevention, but there has been no update on the trends and relative survival (RS). Our aim was (a) to perform a statistical assessment of the incidence trends of CCA and project future trends, and (b) to estimate relative survival.

    Methods: All cases of CCA diagnosed from 1989 through 2013 were abstracted from the Khon Kaen Cancer Registry (KKCR). A jointpoint regression model was used to estimate the annual percentage change (APC) and to project future trends. We also calculated RS.

    Results: There were 11,711 cases of CCA. The incidence rate increased with an APC of 1.79% (95% confidence interval [CI], −0.2 to 3.8) from 1989 through 2002, and decreased with an APC of −6.09% (95% CI, −8.2 to −3.9) from 2002 through 2013. The projected incidence of CCA should stable over the next 10 years, albeit higher than the world rate. The respective 5-year RS for both sexes for age groups of 30–40, 41–45, 51–60, and 61–98 years was 22.3% (95% CI, 16.8–29.5), 14.3% (95% CI, 12.0–17.0), 8.6% (95% CI, 7.8–10.0), and 7.2% (95% CI, 6.4–8.0).

    Conclusion: The incidence rate of CCA has decreased since 2002, representing a real decline in the risk of CCA. The incidence of CCA is projected to stabilize by 2025. The survival of patients with CCA remains poor.

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