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Veisi P, Nikouei M, Cheraghi M, Shahgheibi S, Moradi Y. The association between the multiple birth and breast cancer incidence: an update of a systematic review and meta-analysis from 1983 to 2022. Arch Public Health 2023; 81:76. [PMID: 37106433 PMCID: PMC10142199 DOI: 10.1186/s13690-023-01089-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 04/15/2023] [Indexed: 04/29/2023] Open
Abstract
BACKGROUND It has been assumed that perinatal factors such as multiple pregnancies may affect subsequent breast cancer risk in the mother. Considering the inconsistencies in the results of case-control and cohort studies published in the world, this meta-analysis was conducted in order to determine the exact association between multiple pregnancies (twins or more) and the breast cancer incidence. METHODS This study was performed as a meta-analysis based on PRISMA guidelines by searching the international databases of PubMed (Medline), Scopus, and Web of Science as well as by screening selected articles based on their subject, abstract and full text. The search time was from January 1983 to November 2022. Then the NOS checklist was used to evaluate the quality of the final selected articles. The indicators considered for the meta-analysis included the odds ratio (OR) and the risk ratio (RR) along with the confidence interval reported in the selected primary studies. The desired analyzes were performed with STATA software version 17 to be reported. RESULTS In this meta-analysis, 19 studies were finally selected for analysis, which fully met the inclusion criteria. Of these, 11 were case-control studies and 8 were cohort ones. Their sample size was 263,956 women (48,696 with breast cancer and 215,260 healthy) and 1,658,378 (63,328 twin or multiple pregnancies and 1,595,050 singleton pregnancies), respectively. After combining the results of cohort and case-control studies, the effect of multiple pregnancies on the breast cancer incidence was equal to 1.01 (95% CI: 0.89-1.14; I2: 44.88%, P: 0.06) and 0.89 (95% CI: 0.83-0.95; I2: 41.73%, P: 0.07), respectively. CONCLUSION The present meta-analysis results showed, in general, multiple pregnancies were one of the preventive factors of breast cancer.
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Affiliation(s)
- Pedram Veisi
- Student Research Committee, Kurdistan University of Medical Sciences, Sanandaj, Iran
| | - Maziar Nikouei
- Student Research Committee, Kurdistan University of Medical Sciences, Sanandaj, Iran
| | - Mojtaba Cheraghi
- Student Research Committee, Kurdistan University of Medical Sciences, Sanandaj, Iran.
| | - Sholeh Shahgheibi
- Department of Obstetrics and Gynecology, School of Medicine, Besat Hospital, Kurdistan University of Medical Sciences, Sanandaj, Iran
| | - Yousef Moradi
- Social Determinants of Health Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran.
- Department of Epidemiology and Biostatistics, Faculty of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran.
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Agha M, Eid AF, Nouh M. 3T MRI of the breast with computer aided diagnosis, can it help to avoid unnecessary invasive procedures??? ALEXANDRIA JOURNAL OF MEDICINE 2019. [DOI: 10.1016/j.ajme.2014.12.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Mahmoud Agha
- Medical Research Institute, Alexandria University, Egypt
- Consultant of Diagnostic Imaging, Almana General Hospital, Saudi Arabia
| | - Ahmed Fathi Eid
- Department of Radiology, National Guard Hospital, Saudi Arabia
| | - Mohamed Nouh
- Faculty of Medicine, Alexandria University, Egypt
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Zhao J, Li Y, Zhang Q, Wang Y. Does ovarian stimulation for IVF increase gynaecological cancer risk? A systematic review and meta-analysis. Reprod Biomed Online 2015; 31:20-9. [PMID: 26003452 DOI: 10.1016/j.rbmo.2015.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 03/19/2015] [Accepted: 03/20/2015] [Indexed: 12/12/2022]
Abstract
The aim of this study was to evaluate whether ovarian stimulation for IVF increases the risk of gynaecological cancer, including ovarian, endometrial, cervical and breast cancers, as an independent risk factor. A systematic review and meta-analysis was conducted. Clinical trials that examined the association between ovarian stimulation for IVF and gynaecologic cancers were included. The outcomes of interest were incidence rate of gynaecologic cancers. Twelve cohort studies with 178,396 women exposed to IVF were included; 10 studies were used to analyse ovarian (167,640 women) and breast (151,702 women) cancers, and six studies were identified in the analysis of endometrial (116,672 women) and cervical cancer (114,799 women). Among these studies, 175 ovarian, 48 endometrial, 502 cervical and 866 cases of breast cancer were reported. The meta-analysis found no significant association between ovarian stimulation for IVF and increased ovarian, endometrial, cervical and breast cancer risk (odds ratio [OR] 1.06, 95% confidence interval [CI] 0.85 to 1.32; OR 0.97, 95% CI 0.58 to 1.63; OR 0.43, 95% CI 0.30 to 0.60; OR 0.69, 95% CI 0.63 to 0.76, respectively). Ovarian stimulation for IVF, therefore, does not increase the gynaecologic cancer risk, whether hormone-dependent endometrial and breast cancer or non-hormone-dependent ovarian and cervical cancer.
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Affiliation(s)
- Jing Zhao
- Reproductive Medicine Center, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yanping Li
- Reproductive Medicine Center, Xiangya Hospital, Central South University, Changsha, Hunan, China.
| | - Qiong Zhang
- Reproductive Medicine Center, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Yonggang Wang
- Reproductive Medicine Center, Xiangya Hospital, Central South University, Changsha, Hunan, China
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4
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Sergentanis TN, Diamantaras AA, Perlepe C, Kanavidis P, Skalkidou A, Petridou ET. IVF and breast cancer: a systematic review and meta-analysis. Hum Reprod Update 2013; 20:106-23. [PMID: 23884897 DOI: 10.1093/humupd/dmt034] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND The effects of controlled ovarian hyperstimulation (COH) for IVF in terms of breast cancer risk remain controversial, despite the hormone-dependent nature of the latter. METHODS Eligible studies up to 15 February 2013 were identified and pooled effect estimates for relative risk (RR) were calculated separately for the investigations using the general population and those using infertile women, as a reference group. Fixed- or random-effects models were implemented and subgroup analyses were performed, as appropriate. RESULTS Eight cohort studies were synthesized, yielding a total cohort size of 1,554,332 women among whom 14,961 incident breast cancer cases occurred, encompassing 576 incident breast cancer cases among women exposed to IVF. No significant association between IVF and breast cancer was observed either in the group of studies treating the general population (RR = 0.91, 95% confidence interval (CI): 0.74-1.11) or infertile women (RR = 1.02, 95% CI: 0.88-1.18), as a reference group. Of note were the marginal associations, protective for pregnant and/or parous women after IVF (pooled effect estimate = 0.86, 95% CI: 0.73-1.01) and adverse for women <30 years at first IVF treatment (pooled effect estimate = 1.64, 95% CI: 0.96-2.80). CONCLUSIONS At present, COH for IVF does not seem to impart increased breast cancer risk. Longer follow-up periods, comparisons versus infertile women, subgroup analyses aiming to trace vulnerable subgroups, adjustment for various confounders and larger informative data sets are needed before conclusive statements for the safety of the procedure are reached.
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Affiliation(s)
- Theodoros N Sergentanis
- Department of Hygiene, Epidemiology and Medical Statistics, Medical School, University of Athens, 75 M. Asias Str. Goudi, Athens 115 27, Greece
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Troisi R, Doody DR, Mueller BA. A linked-registry study of gestational factors and subsequent breast cancer risk in the mother. Cancer Epidemiol Biomarkers Prev 2013; 22:835-47. [PMID: 23592822 PMCID: PMC3650095 DOI: 10.1158/1055-9965.epi-12-1375] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Women who were younger at their first live birth have a reduced breast cancer risk. Other pregnancy characteristics, including complications, also may affect risk but because they are rare, require large datasets to study. METHODS The association of pregnancy history and breast cancer risk was assessed in a population-based study including 22,646 cases diagnosed in Washington State 1974 to 2009, and 224,721 controls, frequency matched on parity, age, calendar year of delivery, and race/ethnicity. Information on prediagnosis pregnancies derived from linked birth certificate and hospital discharge databases. Adjusted odd ratios (ORs) and 95% confidence intervals (CI) were calculated. RESULTS Multiple gestation pregnancies were associated with decreased breast cancer risk (OR, 0.65; 95% CI, 0.57-0.74) as was prepregnancy obesity (OR, 0.76; 95% CI, 0.65-0.90). Infant birth weight was positively associated (6% per 1,000 g; 95% CI, 3%-9%). The ORs for first trimester bleeding (OR, 3.35; 95% CI, 1.48-7.55) and placental abnormality/insufficiency (OR, 2.24; 95% CI, 1.08-4.67) were increased in women diagnosed at age 50+ years and 15+ years after the index pregnancy. Results were similar in analyses restricted to first pregnancies, those closest to diagnosis, and when excluding in situ disease. CONCLUSION These data suggest that multiple gestation pregnancies are protective, whereas delivering larger infants increases risk for later development of maternal breast cancer. Placental abnormalities that result in bleeding in pregnancy also may reverse the long-term protection in postmenopausal women associated with parity. IMPACT Certain pregnancy characteristics seem to be associated with later maternal breast cancer risk.
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Affiliation(s)
- Rebecca Troisi
- Epidemiology and Biostatistics Program, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD, USA
| | - David R. Doody
- Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA, Fred Hutchinson Cancer Research Center
| | - Beth A. Mueller
- Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA, Fred Hutchinson Cancer Research Center
- Department of Epidemiology, University of Washington, Seattle, WA, USA, Fred Hutchinson Cancer Research Center
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Kim HS, Woo OH, Park KH, Woo SU, Yang DS, Kim AR, Lee ES, Lee JB, Kim YH, Kim JS, Seo JH. The relationship between twin births and maternal risk of breast cancer: a meta-analysis. Breast Cancer Res Treat 2011; 131:671-7. [DOI: 10.1007/s10549-011-1779-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Accepted: 09/12/2011] [Indexed: 11/27/2022]
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Pregnancy characteristics and maternal breast cancer risk: a review of the epidemiologic literature. Cancer Causes Control 2010; 21:967-89. [PMID: 20224871 DOI: 10.1007/s10552-010-9524-7] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 02/10/2010] [Indexed: 12/16/2022]
Abstract
The short- and long-term effects of pregnancy on breast cancer risk are well documented. Insight into potential biological mechanisms for these associations may be gained by studying breast cancer risk and pregnancy characteristics (e.g., preeclampsia, twining), which may reflect hormone levels during pregnancy. To date, no review has synthesized the published literature for pregnancy characteristics and maternal breast cancer using systematic search methods. We conducted a systematic search to identify all published studies. Using PUBMED (to 31 July 2009), 42 relevant articles were identified. Several studies suggest that multiple births may be associated with a lowered breast cancer risk of about 10-30%, but results were inconsistent across 18 studies. The majority of 13 studies suggest about a 20-30% reduction in risk with preeclampsia and/or gestational hypertension. Six of seven studies reported no association for infant sex and breast cancer risk. Data are sparse and conflicting for other pregnancy characteristics such as gestational age, fetal growth, pregnancy weight gain, gestational diabetes, and placental abnormalities. The most consistent findings in a generally sparse literature are that multiple births and preeclampsia may modestly reduce breast cancer risk. Additional research is needed to elucidate associations between pregnancy characteristics, related hormonal profiles, and breast cancer risk.
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WOHLFAHRT JAN, MELBYE MADS. Pregnancy and Breast Cancer. Breast Cancer 2008. [DOI: 10.3109/9781420058734-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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10
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Troisi R, Potischman N, Hoover RN. Exploring the underlying hormonal mechanisms of prenatal risk factors for breast cancer: a review and commentary. Cancer Epidemiol Biomarkers Prev 2007; 16:1700-12. [PMID: 17855685 DOI: 10.1158/1055-9965.epi-07-0073] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Prenatal factors have been hypothesized to influence subsequent breast cancer development. Directly evaluating the associations of in utero exposures with risk, however, presents several methodologic and theoretical challenges, including the long induction period between exposure and disease and the lack of certainty regarding the critical timing of exposure. Indirect evaluation of these associations has been achieved by use of proxies such as gestational and neonatal characteristics. Evidence suggests that preeclampsia is associated with a reduced breast cancer risk, whereas high birth weight and dizygotic twinning seem associated with an increased risk. Asians born in Asia have substantially lower breast cancer risks than women born in the West. Although data thus far are few, what exists is not consistent with a unifying hypothesis for a particular biological exposure (such as estrogens or androgens) during pregnancy as mediating the observed associations between pregnancy factors and breast cancer risk. This suggests that additional studies of prenatal factors should seek to broaden the range of hormones, growth, and other endocrine factors that are evaluated in utero. Once candidate biomarkers are identified, assessing them with respect to breast cancer and with intermediate end points in carcinogenesis should be a priority. In addition, investigations should explore the possibility that in utero exposures may not act directly on the breast, but may alter other physiologic pathways such as hormone metabolism that have their effect on risk later in life.
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Affiliation(s)
- Rebecca Troisi
- Room 854, Dartmouth-Hitchcock Medical Center, 7297 Rubin Building, One Medical Center Drive, Lebanon, NH 03756, USA.
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11
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Thalib L, Doi SAR, Hall P. Multiple births and breast cancer prognosis: a population based study. Eur J Epidemiol 2006; 20:613-7. [PMID: 16119435 DOI: 10.1007/s10654-005-5530-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Survival in relation to endocrine or reproductive factors has rarely been studied since the focus of most studies has been on the risk of breast cancer. In this study we analysed the effect of multiple birth compared to single births on breast cancer survival. A population based cohort of 30619 women born after 1935 and diagnosed with primary breast cancer, between 1958 and 1998, was generated by linking a number of Swedish registries including Swedish Cancer Registry, Cause of Death Registry, Swedish Generation Registry and the Registry of Population and Population changes. Then we quantified the association between singleton and multiple births to breast cancer specific fatality using the Cox proportional hazards model. We found the singleton and multiple births were associated with increased fatality if breast cancer was diagnosed within 5 years of childbirth, this effect dying out to nil at 5 years after childbirth. Thereafter there was a protective effect on survival with time. Although childbirth is known to decrease breast cancer risk, this study demonstrates that a survival disadvantage exists for breast cancer diagnosed within the first 5 years of singleton and multiple births. It is concluded that breast cancer diagnosed within 5 years of childbirth, particularly if this or prior pregnancies have been multiple, should be regarded as a negative prognostic factor and considered in counselling and treatment of these patients.
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Affiliation(s)
- Lukman Thalib
- Department of Community Medicine and Behavioural Sciences (Biostatistics), Faculty of Medicine, Kuwait University, PO Box 24923, Safat 13110, Kuwait.
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12
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Innes KE, Byers TE. First pregnancy characteristics and subsequent breast cancer risk among young women. Int J Cancer 2004; 112:306-11. [PMID: 15352044 DOI: 10.1002/ijc.20402] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
There is growing evidence that perinatal factors associated with altered gestational hormones may influence subsequent breast cancer risk in the mother. Events occurring during the first pregnancy may be particularly important. In this matched case-control study, we investigated the relation between characteristics of a woman's first pregnancy and her later breast cancer risk using linked records from the New York State birth and tumor registries. Cases were 2,522 women aged 22 to 55 diagnosed with breast cancer between 1978 and 1995 and who had also completed a first pregnancy in New York State (NY) at least 1 year prior to diagnosis. Controls were 10,052 primiparous women not diagnosed with breast or endometrial cancer in NY and matched to cases on county of residence and date of delivery. Information on factors characterizing the woman's first pregnancy was obtained from the pregnancy record of each subject. The association of these factors to breast cancer risk was assessed using conditional logistic regression. Extreme prematurity (< 32 weeks gestational age) was associated with elevated maternal breast cancer risk [adjusted odds ratio (OR)=2.1, 95% confidence interval (CI) 1.2,3.9], as were abruptio placentae (OR = 1.8, CI 1.1,3.0) and multifetal gestation (OR=1.8, CI 1.1,3.0). Preeclampsia was associated with a marked reduction in breast cancer risk among women who bore their first child after age 30 (OR=0.3, CI 0.2,0.7) and in the first 3 years after delivery (OR=0.2 (0.1-0.9). These findings suggest that certain perinatal factors influence maternal breast cancer risk and offer indirect support for a role of gestational hormones, and particularly gestational estrogens, in the etiology of breast cancer.
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Affiliation(s)
- Kim E Innes
- Department of Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, Denver, CO, USA
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Surbone A, Petrek JA. Pregnancy after breast cancer. The relationship of pregnancy to breast cancer development and progression. Crit Rev Oncol Hematol 1998; 27:169-78. [PMID: 9649931 DOI: 10.1016/s1040-8428(97)10038-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Affiliation(s)
- A Surbone
- Memorial Sloan-Kettering Cancer Center, Department of Medicine, New York 10021, USA.
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Lambe M, Hsieh C, Tsaih S, Ekbom A, Adami HO, Trichopoulos D. Maternal risk of breast cancer following multiple births: a nationwide study in Sweden. Cancer Causes Control 1996; 7:533-8. [PMID: 8877051 DOI: 10.1007/bf00051886] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The association between multiple births and subsequent maternal breast cancer risk was explored in a nested case-control study in Sweden encompassing 19,368 parous women with breast cancer diagnosed up to age 65 years, and 100,459 parous controls. Among cases and controls, there were 329 and 2,031 women, respectively, with a history of at least one live multiple birth. Compared with singleton mothers, breast cancer risk was 12 percent lower (odds ratio = 0.88, 95 percent confidence interval = 0.78-0.99) in women who had had a multiple birth. After stratification for age at diagnosis, evidence of a significant inverse association was found only in women aged 54 years or younger. Birth order of the multiple pregnancy had no apparent risk-modifying effect. Age at earliest multiple birth was unrelated to breast cancer risk. The inverse association between twinning and breast cancer risk may reflect protective physiological features of twin pregnancies. Further research is needed to investigate the role, if any, of increased levels of steroid hormone-binding globulins in mothers of twins and the proposed inhibitory effects of human chorionic gonadotropin and alpha-fetoprotein, both of which are increased during multiple gestations, on breast carcinogenesis. Breast feeding patterns in mothers of twins also may modify their risk of developing breast cancer.
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Affiliation(s)
- M Lambe
- Department of Cancer Epidemiology, University Hospital, Uppsala, Sweden
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17
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Dietz AT, Newcomb PA, Storer BE, Longnecker MP, Mittendorf R. Multiple births and risk of breast cancer. Int J Cancer 1995; 62:162-4. [PMID: 7622290 DOI: 10.1002/ijc.2910620209] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Data from a large, multicenter, population-based case-control study were analyzed to investigate the relation between multiple birth pregnancies and subsequent breast-cancer risk in the gravidas. Women less than 75 years old who had breast cancer were identified from statewide tumor registries in Wisconsin, western Massachusetts, Maine and New Hampshire. Controls aged less than 65 years were selected randomly from lists of licensed drivers, and controls aged between 65 and 74 were selected randomly from lists of Medicare beneficiaries. Information on reproductive history and other factors was obtained by means of telephone interviews. After excluding nulliparous women, 5,880 case subjects and 8,217 controls remained for analysis. Multiple birth pregnancies occurred in 146 cases and 218 controls. Adjusted for the number of full-term pregnancies and other confounders, the odds ratio (OR) for any multiple birth pregnancy was 0.94 (95% confidence interval, 0.75 to 1.17). The null association between multiple birth pregnancies and breast cancer remained if the mother's first pregnancy or last pregnancy resulted in a multiple birth. In addition, no trend in risk emerged for age at first multiple birth or time since last multiple birth. While other investigators have suggested biological mechanisms to explain both protective and detrimental effects of multiple births and subsequent development of breast cancer, this study does not support either assertion.
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Affiliation(s)
- A T Dietz
- University of Wisconsin Comprehensive Cancer Center, Madison, USA
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18
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Leon DA, Carpenter LM, Broeders MJ, Gunnarskog J, Murphy MF. Breast cancer in Swedish women before age 50: evidence of a dual effect of completed pregnancy. Cancer Causes Control 1995; 6:283-91. [PMID: 7548715 DOI: 10.1007/bf00051403] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We set out to detect a transient increase in risk of breast cancer following childbirth, the existence of which has been postulated, but for which empirical evidence is contradictory. Breast cancers and births occurring among the cohort of Swedish women born after 1939 were linked, yielding 3,439 cases and 25,140 age-matched controls with at least two children. Within three years of their last childbirth, women had an estimated rate of breast cancer of 1.21 (95 percent confidence interval [CI] = 1.02-1.44) times that of women whose last birth was 10 or more years earlier, after adjustment for parity and age at first birth. Further analyses suggested that this effect reflected, in part, a small transient increase in breast cancer risk that lasts for about three years following completed pregnancy. The effect of age at first birth on breast cancer risk appears to be confounded by time since last birth; the parity-adjusted rate ratio for having a first birth at age 35 years or more compared with under 20 years is reduced from 1.72 (CI = 1.14-2.58) to 1.36 (CI = 0.88-2.09) on additional adjustment for time since last birth. A transient increase in breast cancer risk after childbirth appears thus appears to account for part of the effect of age at first birth on breast cancer risk.
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Affiliation(s)
- D A Leon
- Department of Epidemiology and Population Sciences, London School of Hygiene and Tropical Medicine, UK
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19
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Albrektsen G, Heuch I, Kvåle G. Multiple births, sex of children and subsequent breast-cancer risk for the mothers: a prospective study in Norway. Int J Cancer 1995; 60:341-4. [PMID: 7829241 DOI: 10.1002/ijc.2910600311] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Endocrinological changes occurring during pregnancy may influence the subsequent cancer risk of the mother. Further, the endocrinological milieu may differ according to different birth characteristics. In the present study possible relations between multiple births, sex of children and breast-cancer risk were examined in a population-based, prospective study of 802,269 parous Norwegian women aged 20-56 years. A total of 4,782 women were diagnosed with breast cancer during follow-up. Of these, 97 had ever experienced a multiple birth. We found a slightly lower risk of breast cancer among women ever having had a multiple birth than among women with singletons only (IRR = 0.89, 95% CI = 0.73-1.09). The reduction in risk was mainly observed among women with a multiple last birth. Further, the reduction in risk seemed to diminish with increasing parity, and among women with 4 or more full-term pregnancies, ever having had a multiple birth was associated with an elevated risk (IRR = 1.48, 95% CI = 0.97-2.25). The sex of the first or last child did not affect the subsequent breast-cancer risk. Further, we found no associations with the sex distribution among all children or in multiple births, despite a tendency toward a reduced risk among women with several daughters only.
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Affiliation(s)
- G Albrektsen
- Section for Medical Informatics and Statistics, University of Bergen, Norway
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Michels KB, Hsieh CC, Trichopoulos D, Willett WC. Abortion and breast cancer risk in seven countries. Cancer Causes Control 1995; 6:75-82. [PMID: 7718738 DOI: 10.1007/bf00051683] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Epidemiologic studies have been inconsistent in suggesting an association between abortion and breast cancer risk. Whether the protection provided by a full-term pregnancy also results from a short-term pregnancy or whether a prematurely terminated pregnancy could increase the risk of breast cancer is unclear. Data from a large, international collaborative study were used to evaluate the association between abortions, whether spontaneous or induced, and breast cancer risk. The data from seven countries included 3,958 breast cancer cases and 11,538 hospital controls with information on abortion history obtained through interviews. Compared with nulliparous women with no abortion (baseline), the odds ratios (OR) and 95 percent confidence intervals (CI) were: for nulliparous women with a history of prior abortion, 0.86 (CI = 0.68-1.08); for parous women with no history of abortion, 0.63 (CI = 0.57-0.69); for parous women with abortion before first birth, 0.82 (CI = 0.69-0.97); and, for parous women with abortion only after first birth, 0.70 (CI = 0.63-0.79). When restricting analysis to parous women, those with a history of abortion exhibited an elevated OR suggesting a 29 percent risk increase if the incomplete pregnancy occurred before first birth (CI = 1.16-1.36) and an 11 percent risk increase for abortion only after first birth (CI = 1.02-1.20) compared with women without such history. The associations observed were stronger among the youngest women. These results do not support a large overall association between abortion and breast cancer risk.
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Affiliation(s)
- K B Michels
- Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA
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Hsieh C, Pavia M, Lambe M, Lan SJ, Colditz GA, Ekbom A, Adami HO, Trichopoulos D, Willett WC. Dual effect of parity on breast cancer risk. Eur J Cancer 1994; 30A:969-73. [PMID: 7946593 DOI: 10.1016/0959-8049(94)90125-2] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This study examined whether breast cancer risk increased for a short period after childbirth, but decreased after a longer period of time. Data from an international case-control study on breast cancer conducted in the 1960s were used to study the modifying effect of age at enrolment on the relationship between parity and breast cancer risk, comparing first uniparous with nulliparous women, and then biparous versus uniparous women. The statistical analysis was performed by modelling through multiple logistic regression, adjusting for study site, age at menarche, menopausal status and obesity index. Comparing uniparous with nulliparous women, an early age at birth seems to be protective for all periods after birth, whereas a late age at birth imparts a higher risk than nulliparity in the period immediately after birth, which declines with the passage of time. The modification effect by age was not apparent when biparous women with different age at second birth were compared with uniparous women. The results support the hypothesis that pregnancy oestrogens impart a transient increase of maternal breast cancer risk when the full-term pregnancy occurs late in a woman's life.
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Affiliation(s)
- C Hsieh
- Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts 02115
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