Twinship and risk of postmenopausal breast cancer

James R Cerhan, Lawrence H. Kushi, Janet E Olson, Stephen S. Rich, Wei Zheng, Aaron R. Folsom, Thomas A. Sellers

Research output: Contribution to journalArticle

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Abstract

Background: Intrauterine exposure to high levels of endogenous estrogens has been hypothesized to increase the risk of breast cancer. Because estrogens and other pregnancy hormones are substantially elevated in twin pregnancies, and possibly more so in dizygotic twin pregnancies, we evaluated the association between aspects of twin membership (i.e., belonging to a twin pair) and the risk of breast cancer. Methods: In a cohort of 29 197 postmenopausal Iowa women with no prior diagnosis of cancer (except for nonmelanoma skin cancer), breast cancer risk factors were determined by use of a mailed questionnaire in 1986 (baseline); twin membership, sex of the twin, and zygosity were determined by use of a follow-up questionnaire in 1992. Results: Within the cohort, 1.8% (n = 538) of the women reported being a twin; of these 24% (n = 130) were monozygotic twins, 63% (n = 337) were dizygotic twins, and 13% (n = 71) did not know their zygosity. From 1986 through 1996, 1230 breast cancers in the cohort were ascertained by linkage to the Iowa Cancer Registry.o Compared with singletons, women who belonged to a twin pair were at elevated risk of breast cancer (multivariate-adjusted risk ratio [RR] = 1.72; 95% confidence interval [CI = 1.22-2.42), with adjustment for educational level, family history of breast cancer, height, body mass index, body fat distribution, age at menarche, age at first live birth, use of hormone replacement therapy, and alcohol use. Multivariate- adjusted risk was elevated (in comparison with singletons) if the sex of the other twin was female (RR = 1.82; 95% CI = 1.20-2.75); however, this risk was limited to female dizygotic twins (RR = 2.14; 95% CI = 1.21-+3.79), since no excess risk was evident for monozygotic twins (RR = 1.04; 95% CI = 0.43- 2.50). The risk to women with a male twin was also elevated (RR = 1.49; 95% CI = 0.80-2.78) in comparison with singletons, but this estimate was not statistically significant. Conclusions: This cohort study lends further support to the theory that there are important intrauterine influences on carcinogenesis of the breast.

Original languageEnglish (US)
Pages (from-to)261-265
Number of pages5
JournalJournal of the National Cancer Institute
Volume92
Issue number3
StatePublished - Feb 2 2000

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Breast Neoplasms
Dizygotic Twins
Odds Ratio
Twin Pregnancy
Monozygotic Twins
Estrogens
Body Fat Distribution
Menarche
Birth Order
Hormone Replacement Therapy
Live Birth
Skin Neoplasms
Registries
Neoplasms
Carcinogenesis
Breast
Body Mass Index
Cohort Studies
Alcohols
Hormones

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

Cerhan, J. R., Kushi, L. H., Olson, J. E., Rich, S. S., Zheng, W., Folsom, A. R., & Sellers, T. A. (2000). Twinship and risk of postmenopausal breast cancer. Journal of the National Cancer Institute, 92(3), 261-265.

Twinship and risk of postmenopausal breast cancer. / Cerhan, James R; Kushi, Lawrence H.; Olson, Janet E; Rich, Stephen S.; Zheng, Wei; Folsom, Aaron R.; Sellers, Thomas A.

In: Journal of the National Cancer Institute, Vol. 92, No. 3, 02.02.2000, p. 261-265.

Research output: Contribution to journalArticle

Cerhan, JR, Kushi, LH, Olson, JE, Rich, SS, Zheng, W, Folsom, AR & Sellers, TA 2000, 'Twinship and risk of postmenopausal breast cancer', Journal of the National Cancer Institute, vol. 92, no. 3, pp. 261-265.
Cerhan JR, Kushi LH, Olson JE, Rich SS, Zheng W, Folsom AR et al. Twinship and risk of postmenopausal breast cancer. Journal of the National Cancer Institute. 2000 Feb 2;92(3):261-265.
Cerhan, James R ; Kushi, Lawrence H. ; Olson, Janet E ; Rich, Stephen S. ; Zheng, Wei ; Folsom, Aaron R. ; Sellers, Thomas A. / Twinship and risk of postmenopausal breast cancer. In: Journal of the National Cancer Institute. 2000 ; Vol. 92, No. 3. pp. 261-265.
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abstract = "Background: Intrauterine exposure to high levels of endogenous estrogens has been hypothesized to increase the risk of breast cancer. Because estrogens and other pregnancy hormones are substantially elevated in twin pregnancies, and possibly more so in dizygotic twin pregnancies, we evaluated the association between aspects of twin membership (i.e., belonging to a twin pair) and the risk of breast cancer. Methods: In a cohort of 29 197 postmenopausal Iowa women with no prior diagnosis of cancer (except for nonmelanoma skin cancer), breast cancer risk factors were determined by use of a mailed questionnaire in 1986 (baseline); twin membership, sex of the twin, and zygosity were determined by use of a follow-up questionnaire in 1992. Results: Within the cohort, 1.8{\%} (n = 538) of the women reported being a twin; of these 24{\%} (n = 130) were monozygotic twins, 63{\%} (n = 337) were dizygotic twins, and 13{\%} (n = 71) did not know their zygosity. From 1986 through 1996, 1230 breast cancers in the cohort were ascertained by linkage to the Iowa Cancer Registry.o Compared with singletons, women who belonged to a twin pair were at elevated risk of breast cancer (multivariate-adjusted risk ratio [RR] = 1.72; 95{\%} confidence interval [CI = 1.22-2.42), with adjustment for educational level, family history of breast cancer, height, body mass index, body fat distribution, age at menarche, age at first live birth, use of hormone replacement therapy, and alcohol use. Multivariate- adjusted risk was elevated (in comparison with singletons) if the sex of the other twin was female (RR = 1.82; 95{\%} CI = 1.20-2.75); however, this risk was limited to female dizygotic twins (RR = 2.14; 95{\%} CI = 1.21-+3.79), since no excess risk was evident for monozygotic twins (RR = 1.04; 95{\%} CI = 0.43- 2.50). The risk to women with a male twin was also elevated (RR = 1.49; 95{\%} CI = 0.80-2.78) in comparison with singletons, but this estimate was not statistically significant. Conclusions: This cohort study lends further support to the theory that there are important intrauterine influences on carcinogenesis of the breast.",
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T1 - Twinship and risk of postmenopausal breast cancer

AU - Cerhan, James R

AU - Kushi, Lawrence H.

AU - Olson, Janet E

AU - Rich, Stephen S.

AU - Zheng, Wei

AU - Folsom, Aaron R.

AU - Sellers, Thomas A.

PY - 2000/2/2

Y1 - 2000/2/2

N2 - Background: Intrauterine exposure to high levels of endogenous estrogens has been hypothesized to increase the risk of breast cancer. Because estrogens and other pregnancy hormones are substantially elevated in twin pregnancies, and possibly more so in dizygotic twin pregnancies, we evaluated the association between aspects of twin membership (i.e., belonging to a twin pair) and the risk of breast cancer. Methods: In a cohort of 29 197 postmenopausal Iowa women with no prior diagnosis of cancer (except for nonmelanoma skin cancer), breast cancer risk factors were determined by use of a mailed questionnaire in 1986 (baseline); twin membership, sex of the twin, and zygosity were determined by use of a follow-up questionnaire in 1992. Results: Within the cohort, 1.8% (n = 538) of the women reported being a twin; of these 24% (n = 130) were monozygotic twins, 63% (n = 337) were dizygotic twins, and 13% (n = 71) did not know their zygosity. From 1986 through 1996, 1230 breast cancers in the cohort were ascertained by linkage to the Iowa Cancer Registry.o Compared with singletons, women who belonged to a twin pair were at elevated risk of breast cancer (multivariate-adjusted risk ratio [RR] = 1.72; 95% confidence interval [CI = 1.22-2.42), with adjustment for educational level, family history of breast cancer, height, body mass index, body fat distribution, age at menarche, age at first live birth, use of hormone replacement therapy, and alcohol use. Multivariate- adjusted risk was elevated (in comparison with singletons) if the sex of the other twin was female (RR = 1.82; 95% CI = 1.20-2.75); however, this risk was limited to female dizygotic twins (RR = 2.14; 95% CI = 1.21-+3.79), since no excess risk was evident for monozygotic twins (RR = 1.04; 95% CI = 0.43- 2.50). The risk to women with a male twin was also elevated (RR = 1.49; 95% CI = 0.80-2.78) in comparison with singletons, but this estimate was not statistically significant. Conclusions: This cohort study lends further support to the theory that there are important intrauterine influences on carcinogenesis of the breast.

AB - Background: Intrauterine exposure to high levels of endogenous estrogens has been hypothesized to increase the risk of breast cancer. Because estrogens and other pregnancy hormones are substantially elevated in twin pregnancies, and possibly more so in dizygotic twin pregnancies, we evaluated the association between aspects of twin membership (i.e., belonging to a twin pair) and the risk of breast cancer. Methods: In a cohort of 29 197 postmenopausal Iowa women with no prior diagnosis of cancer (except for nonmelanoma skin cancer), breast cancer risk factors were determined by use of a mailed questionnaire in 1986 (baseline); twin membership, sex of the twin, and zygosity were determined by use of a follow-up questionnaire in 1992. Results: Within the cohort, 1.8% (n = 538) of the women reported being a twin; of these 24% (n = 130) were monozygotic twins, 63% (n = 337) were dizygotic twins, and 13% (n = 71) did not know their zygosity. From 1986 through 1996, 1230 breast cancers in the cohort were ascertained by linkage to the Iowa Cancer Registry.o Compared with singletons, women who belonged to a twin pair were at elevated risk of breast cancer (multivariate-adjusted risk ratio [RR] = 1.72; 95% confidence interval [CI = 1.22-2.42), with adjustment for educational level, family history of breast cancer, height, body mass index, body fat distribution, age at menarche, age at first live birth, use of hormone replacement therapy, and alcohol use. Multivariate- adjusted risk was elevated (in comparison with singletons) if the sex of the other twin was female (RR = 1.82; 95% CI = 1.20-2.75); however, this risk was limited to female dizygotic twins (RR = 2.14; 95% CI = 1.21-+3.79), since no excess risk was evident for monozygotic twins (RR = 1.04; 95% CI = 0.43- 2.50). The risk to women with a male twin was also elevated (RR = 1.49; 95% CI = 0.80-2.78) in comparison with singletons, but this estimate was not statistically significant. Conclusions: This cohort study lends further support to the theory that there are important intrauterine influences on carcinogenesis of the breast.

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