Abstract
Background: Parity is widely recognized as protective for breast cancer, but breast cancer risk may be increased shortly after childbirth. Whether this risk varies with breastfeeding, family history of breast cancer, or specific tumor subtype has rarely been evaluated. Objective: To characterize breast cancer risk in relation to recent childbirth. Design: Pooled analysis of individual-level data from 15 prospective cohort studies. Setting: The international Premenopausal Breast Cancer Collaborative Group. Participants: Women younger than 55 years. Measurements: During 9.6 million person-years of follow-up, 18 826 incident cases of breast cancer were diagnosed. Hazard ratios (HRs) and 95% CIs for breast cancer were calculated using Cox proportional hazards regression. Results: Compared with nulliparous women, parous women had an HR for breast cancer that peaked about 5 years after birth (HR, 1.80 [95% CI, 1.63 to 1.99]) before decreasing to 0.77 (CI, 0.67 to 0.88) after 34 years. The association crossed over from positive to negative about 24 years after birth. The overall pattern was driven by estrogen receptor (ER)-positive breast cancer; no crossover was seen for ER-negative cancer. Increases in breast cancer risk after childbirth were pronounced when combined with a family history of breast cancer and were greater for women who were older at first birth or who had more births. Breastfeeding did not modify overall risk patterns. Limitations: Breast cancer diagnoses during pregnancy were not uniformly distinguishable from early postpartum diagnoses. Data on human epidermal growth factor receptor 2 (HER2) oncogene overexpression were limited. Conclusion: Compared with nulliparous women, parous women have an increased risk for breast cancer for more than 20 years after childbirth. Health care providers should consider recent childbirth a risk factor for breast cancer in young women.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 22-30 |
| Number of pages | 9 |
| Journal | Annals of Internal Medicine |
| Volume | 170 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 1 2019 |
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ASJC Scopus subject areas
- Internal Medicine
Cite this
Breast cancer risk after recent childbirth : A pooled analysis of 15 prospective studies. / Nichols, Hazel B.; Schoemaker, Minouk J.; Cai, Jianwen; Xu, Jiawei; Wright, Lauren B.; Brook, Mark N.; Jones, Michael E.; Adami, Hans Olov; Baglietto, Laura; Bertrand, Kimberly A.; Blot, William J.; Boutron-Ruault, Marie Christine; Dorronsoro, Miren; Dossus, Laure; Eliassen, A. Heather; Giles, Graham G.; Gram, Inger T.; Hankinson, Susan E.; Hoffman-Bolton, Judy; Kaaks, Rudolf; Key, Timothy J.; Kitahara, Cari M.; Larsson, Susanna C.; Linet, Martha; Merritt, Melissa A.; Milne, Roger L.; Pala, Valeria; Palmer, Julie R.; Peeters, Petra H.; Riboli, Elio; Sund, Malin; Tamimi, Rulla M.; Tjønneland, Anne; Trichopoulou, Antonia; Ursin, Giske; Vatten, Lars; Visvanathan, Kala; Weiderpass, Elisabete; Wolk, Alicja; Zheng, Wei; Weinberg, Clarice R.; Swerdlow, Anthony J.; Sandler, Dale P.
In: Annals of Internal Medicine, Vol. 170, No. 1, 01.01.2019, p. 22-30.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Breast cancer risk after recent childbirth
T2 - A pooled analysis of 15 prospective studies
AU - Nichols, Hazel B.
AU - Schoemaker, Minouk J.
AU - Cai, Jianwen
AU - Xu, Jiawei
AU - Wright, Lauren B.
AU - Brook, Mark N.
AU - Jones, Michael E.
AU - Adami, Hans Olov
AU - Baglietto, Laura
AU - Bertrand, Kimberly A.
AU - Blot, William J.
AU - Boutron-Ruault, Marie Christine
AU - Dorronsoro, Miren
AU - Dossus, Laure
AU - Eliassen, A. Heather
AU - Giles, Graham G.
AU - Gram, Inger T.
AU - Hankinson, Susan E.
AU - Hoffman-Bolton, Judy
AU - Kaaks, Rudolf
AU - Key, Timothy J.
AU - Kitahara, Cari M.
AU - Larsson, Susanna C.
AU - Linet, Martha
AU - Merritt, Melissa A.
AU - Milne, Roger L.
AU - Pala, Valeria
AU - Palmer, Julie R.
AU - Peeters, Petra H.
AU - Riboli, Elio
AU - Sund, Malin
AU - Tamimi, Rulla M.
AU - Tjønneland, Anne
AU - Trichopoulou, Antonia
AU - Ursin, Giske
AU - Vatten, Lars
AU - Visvanathan, Kala
AU - Weiderpass, Elisabete
AU - Wolk, Alicja
AU - Zheng, Wei
AU - Weinberg, Clarice R.
AU - Swerdlow, Anthony J.
AU - Sandler, Dale P.
PY - 2019/1/1
Y1 - 2019/1/1
N2 - Background: Parity is widely recognized as protective for breast cancer, but breast cancer risk may be increased shortly after childbirth. Whether this risk varies with breastfeeding, family history of breast cancer, or specific tumor subtype has rarely been evaluated. Objective: To characterize breast cancer risk in relation to recent childbirth. Design: Pooled analysis of individual-level data from 15 prospective cohort studies. Setting: The international Premenopausal Breast Cancer Collaborative Group. Participants: Women younger than 55 years. Measurements: During 9.6 million person-years of follow-up, 18 826 incident cases of breast cancer were diagnosed. Hazard ratios (HRs) and 95% CIs for breast cancer were calculated using Cox proportional hazards regression. Results: Compared with nulliparous women, parous women had an HR for breast cancer that peaked about 5 years after birth (HR, 1.80 [95% CI, 1.63 to 1.99]) before decreasing to 0.77 (CI, 0.67 to 0.88) after 34 years. The association crossed over from positive to negative about 24 years after birth. The overall pattern was driven by estrogen receptor (ER)-positive breast cancer; no crossover was seen for ER-negative cancer. Increases in breast cancer risk after childbirth were pronounced when combined with a family history of breast cancer and were greater for women who were older at first birth or who had more births. Breastfeeding did not modify overall risk patterns. Limitations: Breast cancer diagnoses during pregnancy were not uniformly distinguishable from early postpartum diagnoses. Data on human epidermal growth factor receptor 2 (HER2) oncogene overexpression were limited. Conclusion: Compared with nulliparous women, parous women have an increased risk for breast cancer for more than 20 years after childbirth. Health care providers should consider recent childbirth a risk factor for breast cancer in young women.
AB - Background: Parity is widely recognized as protective for breast cancer, but breast cancer risk may be increased shortly after childbirth. Whether this risk varies with breastfeeding, family history of breast cancer, or specific tumor subtype has rarely been evaluated. Objective: To characterize breast cancer risk in relation to recent childbirth. Design: Pooled analysis of individual-level data from 15 prospective cohort studies. Setting: The international Premenopausal Breast Cancer Collaborative Group. Participants: Women younger than 55 years. Measurements: During 9.6 million person-years of follow-up, 18 826 incident cases of breast cancer were diagnosed. Hazard ratios (HRs) and 95% CIs for breast cancer were calculated using Cox proportional hazards regression. Results: Compared with nulliparous women, parous women had an HR for breast cancer that peaked about 5 years after birth (HR, 1.80 [95% CI, 1.63 to 1.99]) before decreasing to 0.77 (CI, 0.67 to 0.88) after 34 years. The association crossed over from positive to negative about 24 years after birth. The overall pattern was driven by estrogen receptor (ER)-positive breast cancer; no crossover was seen for ER-negative cancer. Increases in breast cancer risk after childbirth were pronounced when combined with a family history of breast cancer and were greater for women who were older at first birth or who had more births. Breastfeeding did not modify overall risk patterns. Limitations: Breast cancer diagnoses during pregnancy were not uniformly distinguishable from early postpartum diagnoses. Data on human epidermal growth factor receptor 2 (HER2) oncogene overexpression were limited. Conclusion: Compared with nulliparous women, parous women have an increased risk for breast cancer for more than 20 years after childbirth. Health care providers should consider recent childbirth a risk factor for breast cancer in young women.
UR - http://www.scopus.com/inward/record.url?scp=85059477603&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85059477603&partnerID=8YFLogxK
U2 - 10.7326/M18-1323
DO - 10.7326/M18-1323
M3 - Article
C2 - 30534999
AN - SCOPUS:85059477603
VL - 170
SP - 22
EP - 30
JO - Annals of Internal Medicine
JF - Annals of Internal Medicine
SN - 0003-4819
IS - 1
ER -