TY - JOUR
T1 - Body mass index and breast cancer risk in Japan
T2 - A pooled analysis of eight population-based cohort studies
AU - Wada, K.
AU - Nagata, C.
AU - Tamakoshi, A.
AU - Matsuo, K.
AU - Oze, I.
AU - Wakai, K.
AU - Tsuji, I.
AU - Sugawara, Y.
AU - Mizoue, T.
AU - Tanaka, K.
AU - Iwasaki, M.
AU - Inoue, M.
AU - Tsugane, S.
AU - Sasazuki, S.
N1 - Funding Information:
This work was supported in part by the National Cancer Center Research and Development Fund (24-A-3).
PY - 2014/2
Y1 - 2014/2
N2 - Background: A positive association between body mass index (BMI) and breast cancer risk among postmenopausal women has been reported, and a weak inverse association has been suggested among premenopausal women from studies in the Western population. The effects of BMI on breast cancer have remained unclear among the Asian population, especially in premenopausal women. Methods: We assessed the associations between BMI and breast cancer incidence by a pooled analysis from eight representative large-scale cohort studies in Japan. Cancer incidence was mainly confirmed through regional populationbased cancer registries and/or through active patient notification from major local hospitals. Breast cancer was defined as code C50 according to ICD10. Pooled estimates of the hazard ratios (HRs) and 95% confidence interval (CIs) for breast cancer were calculated using random-effects models. Results: Analytic subjects were 183 940 women, 1783 of whom had breast cancer during 2 194 211 person-years of follow-up. A positive association between BMI and the risk of postmenopausal breast cancer was observed (trend P < 0.001). The HRs for premenopausal breast cancer were 1.05 (95% CI 0.56-1.99), 1.07 (95% CI 0.76-1.52), 0.91 (95% CI 0.64-1.30), 1.15 (95% CI 0.76-1.73), 1.45 (95% CI 0.71-2.94), and 2.25 (95% CI 1.10-4.60), respectively, in BMIs of <19, 19 to <21, 21 to <23, 25 to <27, 27 to <30, and ≥30 kg/m2. These results were not substantially altered after excluding the patients who were diagnosed with breast cancer in the first 2 years of follow-up. Conclusions: The increased risk of postmenopausal breast cancer among women with higher BMIs was confirmed in Japanese. A borderline-significant positive association between BMI and premenopausal breast cancer was observed, suggesting that body mass in Asian women might have opposite effects on breast cancer compared with Western women.
AB - Background: A positive association between body mass index (BMI) and breast cancer risk among postmenopausal women has been reported, and a weak inverse association has been suggested among premenopausal women from studies in the Western population. The effects of BMI on breast cancer have remained unclear among the Asian population, especially in premenopausal women. Methods: We assessed the associations between BMI and breast cancer incidence by a pooled analysis from eight representative large-scale cohort studies in Japan. Cancer incidence was mainly confirmed through regional populationbased cancer registries and/or through active patient notification from major local hospitals. Breast cancer was defined as code C50 according to ICD10. Pooled estimates of the hazard ratios (HRs) and 95% confidence interval (CIs) for breast cancer were calculated using random-effects models. Results: Analytic subjects were 183 940 women, 1783 of whom had breast cancer during 2 194 211 person-years of follow-up. A positive association between BMI and the risk of postmenopausal breast cancer was observed (trend P < 0.001). The HRs for premenopausal breast cancer were 1.05 (95% CI 0.56-1.99), 1.07 (95% CI 0.76-1.52), 0.91 (95% CI 0.64-1.30), 1.15 (95% CI 0.76-1.73), 1.45 (95% CI 0.71-2.94), and 2.25 (95% CI 1.10-4.60), respectively, in BMIs of <19, 19 to <21, 21 to <23, 25 to <27, 27 to <30, and ≥30 kg/m2. These results were not substantially altered after excluding the patients who were diagnosed with breast cancer in the first 2 years of follow-up. Conclusions: The increased risk of postmenopausal breast cancer among women with higher BMIs was confirmed in Japanese. A borderline-significant positive association between BMI and premenopausal breast cancer was observed, suggesting that body mass in Asian women might have opposite effects on breast cancer compared with Western women.
KW - Body mass index
KW - Breast cancer
KW - Cohort study
KW - Pooled analysis
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U2 - 10.1093/annonc/mdt542
DO - 10.1093/annonc/mdt542
M3 - Article
C2 - 24412821
AN - SCOPUS:84893377867
VL - 25
SP - 519
EP - 524
JO - Annals of Oncology
JF - Annals of Oncology
SN - 0923-7534
IS - 2
ER -