Abstract
The incidence of breast cancer among Japanese women, a traditionally low-risk population, has increased substantially. To evaluate the association of reproductive factors with breast cancer risk, we examined 38 159 Japanese women, aged 40-79 years, who responded to a questionnaire on reproductive and other lifestyle factors from 1988 to 1990 in the Japan Collaborative Cohort Study. During an average 7.6 years of follow-up, we documented 151 incidents of breast cancers. Cox proportional hazards modeling was employed to estimate relative risks (RR) and 95% confidence intervals (CI). There was a significant decline in the risk of breast cancer with increasing parity among parous women (trend P = 0.01). Women with four or more parities had a 69% lower risk than uniparous women, a reduced risk was also evident among menopausal women. Breast cancer risk tended to rise with increasing age at first delivery (trend P = 0.05), the association being very apparent among menopausal women (trend P = 0.02). Compared to the women who had their first delivery before age 25, those who delayed this event until after age 34 had an RR of 2.12 (95% CI: 0.72-6.21) and 3.33 (1.07-10.3) among the overall subjects and the menopausal, respectively. There was no apparent association of breast cancer risk with age at menarche or menopause. Our study concerning reproductive risk factors suggests that breast cancer in Japan is similar to that in Western countries, and that reproductive factors, particularly the number of parity and age at first delivery, might be important in the etiology of breast cancer among Japanese women.
| Original language | English |
|---|---|
| Pages (from-to) | 57-62 |
| Number of pages | 6 |
| Journal | Cancer Science |
| Volume | 96 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 01-01-2005 |
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All Science Journal Classification (ASJC) codes
- Oncology
- Cancer Research
Cite this
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Impact of menstrual and reproductive factors on breast cancer risk in Japan : Results of the JACC study. / Tamakoshi, Koji; Yatsuya, Hiroshi; Wakai, Kenji; Suzuki, Sadao; Nishio, Kazuko; Lin, Yingsong; Niwa, Yoshimitsu; Kondo, Takaaki; Yamamoto, Akio; Tokudome, Shinkan; Toyoshima, Hideaki; Tamakoshi, Akiko; Mori, Mitsuru; Motohashi, Yutaka; Tsuji, Ichiro; Nakamura, Yosikazu; Iso, Hiroyasu; Mikami, Haruo; Inaba, Yutaka; Hoshiyama, Yoshiharu; Suzuki, Hiroshi; Shimizu, Hiroyuki; Ito, Yoshinori; Hashimoto, Shuji; Kikuchi, Shogo; Koizumi, Akio; Kawamura, Takashi; Watanabe, Yoshiyuki; Miki, Tsuneharu; Date, Chigusa; Sakata, Kiyomi; Nose, Takayuki; Hayakawa, Norihiko; Yoshimura, Takesumi; Shibata, Akira; Okamoto, Naoyuki; Shio, Hideo; Ohno, Yoshiyuki; Kitagawa, Tomoyuki; Kuroki, Toshio; Tajima, Kazuo; Shimamoto, Takashi; Tanaka, Heizo; Hisamichi, Shigeru; Nakao, Masahiro; Suzuki, Takaichiro; Hashimoto, Tsutomu; Ishibashi, Teruo; Fukuda, Katsuhiro.
In: Cancer Science, Vol. 96, No. 1, 01.01.2005, p. 57-62.Research output: Contribution to journal › Article
TY - JOUR
T1 - Impact of menstrual and reproductive factors on breast cancer risk in Japan
T2 - Results of the JACC study
AU - Tamakoshi, Koji
AU - Yatsuya, Hiroshi
AU - Wakai, Kenji
AU - Suzuki, Sadao
AU - Nishio, Kazuko
AU - Lin, Yingsong
AU - Niwa, Yoshimitsu
AU - Kondo, Takaaki
AU - Yamamoto, Akio
AU - Tokudome, Shinkan
AU - Toyoshima, Hideaki
AU - Tamakoshi, Akiko
AU - Mori, Mitsuru
AU - Motohashi, Yutaka
AU - Tsuji, Ichiro
AU - Nakamura, Yosikazu
AU - Iso, Hiroyasu
AU - Mikami, Haruo
AU - Inaba, Yutaka
AU - Hoshiyama, Yoshiharu
AU - Suzuki, Hiroshi
AU - Shimizu, Hiroyuki
AU - Ito, Yoshinori
AU - Hashimoto, Shuji
AU - Kikuchi, Shogo
AU - Koizumi, Akio
AU - Kawamura, Takashi
AU - Watanabe, Yoshiyuki
AU - Miki, Tsuneharu
AU - Date, Chigusa
AU - Sakata, Kiyomi
AU - Nose, Takayuki
AU - Hayakawa, Norihiko
AU - Yoshimura, Takesumi
AU - Shibata, Akira
AU - Okamoto, Naoyuki
AU - Shio, Hideo
AU - Ohno, Yoshiyuki
AU - Kitagawa, Tomoyuki
AU - Kuroki, Toshio
AU - Tajima, Kazuo
AU - Shimamoto, Takashi
AU - Tanaka, Heizo
AU - Hisamichi, Shigeru
AU - Nakao, Masahiro
AU - Suzuki, Takaichiro
AU - Hashimoto, Tsutomu
AU - Ishibashi, Teruo
AU - Fukuda, Katsuhiro
PY - 2005/1/1
Y1 - 2005/1/1
N2 - The incidence of breast cancer among Japanese women, a traditionally low-risk population, has increased substantially. To evaluate the association of reproductive factors with breast cancer risk, we examined 38 159 Japanese women, aged 40-79 years, who responded to a questionnaire on reproductive and other lifestyle factors from 1988 to 1990 in the Japan Collaborative Cohort Study. During an average 7.6 years of follow-up, we documented 151 incidents of breast cancers. Cox proportional hazards modeling was employed to estimate relative risks (RR) and 95% confidence intervals (CI). There was a significant decline in the risk of breast cancer with increasing parity among parous women (trend P = 0.01). Women with four or more parities had a 69% lower risk than uniparous women, a reduced risk was also evident among menopausal women. Breast cancer risk tended to rise with increasing age at first delivery (trend P = 0.05), the association being very apparent among menopausal women (trend P = 0.02). Compared to the women who had their first delivery before age 25, those who delayed this event until after age 34 had an RR of 2.12 (95% CI: 0.72-6.21) and 3.33 (1.07-10.3) among the overall subjects and the menopausal, respectively. There was no apparent association of breast cancer risk with age at menarche or menopause. Our study concerning reproductive risk factors suggests that breast cancer in Japan is similar to that in Western countries, and that reproductive factors, particularly the number of parity and age at first delivery, might be important in the etiology of breast cancer among Japanese women.
AB - The incidence of breast cancer among Japanese women, a traditionally low-risk population, has increased substantially. To evaluate the association of reproductive factors with breast cancer risk, we examined 38 159 Japanese women, aged 40-79 years, who responded to a questionnaire on reproductive and other lifestyle factors from 1988 to 1990 in the Japan Collaborative Cohort Study. During an average 7.6 years of follow-up, we documented 151 incidents of breast cancers. Cox proportional hazards modeling was employed to estimate relative risks (RR) and 95% confidence intervals (CI). There was a significant decline in the risk of breast cancer with increasing parity among parous women (trend P = 0.01). Women with four or more parities had a 69% lower risk than uniparous women, a reduced risk was also evident among menopausal women. Breast cancer risk tended to rise with increasing age at first delivery (trend P = 0.05), the association being very apparent among menopausal women (trend P = 0.02). Compared to the women who had their first delivery before age 25, those who delayed this event until after age 34 had an RR of 2.12 (95% CI: 0.72-6.21) and 3.33 (1.07-10.3) among the overall subjects and the menopausal, respectively. There was no apparent association of breast cancer risk with age at menarche or menopause. Our study concerning reproductive risk factors suggests that breast cancer in Japan is similar to that in Western countries, and that reproductive factors, particularly the number of parity and age at first delivery, might be important in the etiology of breast cancer among Japanese women.
UR - http://www.scopus.com/inward/record.url?scp=85047691285&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85047691285&partnerID=8YFLogxK
U2 - 10.1111/j.1349-7006.2005.00010.x
DO - 10.1111/j.1349-7006.2005.00010.x
M3 - Article
VL - 96
SP - 57
EP - 62
JO - Cancer Science
JF - Cancer Science
SN - 1347-9032
IS - 1
ER -