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Parity, hormones and breast cancer subtypes - results from a large nested case-control study in a national screening program.
Breast Cancer Res 2017; 19(1):10BC

Abstract

BACKGROUND

Breast cancer comprises several molecular subtypes with different prognoses and possibly different etiology. Reproductive and hormonal factors are associated with breast cancer overall, and with luminal subtypes, but the associations with other subtypes are unclear. We used data from a national screening program to conduct a large nested case-control study.

METHODS

We conducted a nested case-control study on participants in the Norwegian Breast Cancer Screening Program in 2006 - 2014. There was information on estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) for 4748 cases of breast cancer. Breast cancer subtypes were defined as luminal A-like (ER+ PR+ HER2-), luminal B-like (ER+ PR- HER2- or ER+ PR+/PR-HER2+), HER2-positive (ER- PR- HER2+) and triple-negative (ER- PR- HER2-). Conditional logistic regression was used to estimate odds ratios (ORs) of breast cancer associated with age at first birth, number of pregnancies, oral contraceptive use, intrauterine devices and menopausal hormone therapy. Analyses were adjusted for age, body mass index, education, age at menarche, number of pregnancies and menopausal status.

RESULTS

Number of pregnancies was inversely associated with relative risk of luminal-like breast cancers (p-trend ≤0.02), and although not statistically significant, with HER2-positive (OR = 0.60, 95% CI 0.31-1.19) and triple-negative cancer (OR = 0.70, 95% CI 0.41-1.21). Women who had ≥4 pregnancies were at >40% lower risk of luminal-like and HER2-positive cancers than women who had never been pregnant. However, there was a larger discrepancy between tumor subtypes with menopausal hormone use. Women who used estrogen and progesterone therapy (EPT) had almost threefold increased risk of luminal A-like cancer (OR = 2.92, 95% CI 2.36-3.62) compared to never-users, but were not at elevated risk of HER2-positive (OR = 0.88, 95% CI 0.33-2.30) or triple-negative (OR = 0.92, 95% CI 0.43 - 1.98) subtypes.

CONCLUSIONS

Reproductive factors were to some extent associated with all subtypes; the strongest trends were with luminal-like subtypes. Hormone therapy use was strongly associated with risk of luminal-like breast cancer, and less so with risk of HER2-positive or triple-negative cancer. There are clearly some, but possibly limited, etiologic differences between subtypes, with the greatest contrast between luminal A-like and triple-negative subtypes.

TRIAL REGISTRATION

Not applicable.

Authors+Show Affiliations

Cancer Registry of Norway, Oslo, Norway.Cancer Registry of Norway, Oslo, Norway.Cancer Registry of Norway, Oslo, Norway.Cancer Registry of Norway, Oslo, Norway.Department of Non-Communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK.Cancer Registry of Norway, Oslo, Norway. Giske.Ursin@kreftregisteret.no. University of Oslo, Oslo, Norway. Giske.Ursin@kreftregisteret.no. University of Southern California, Los Angeles, CA, USA. Giske.Ursin@kreftregisteret.no.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

28114999

Citation

Ellingjord-Dale, Merete, et al. "Parity, Hormones and Breast Cancer Subtypes - Results From a Large Nested Case-control Study in a National Screening Program." Breast Cancer Research : BCR, vol. 19, no. 1, 2017, p. 10.
Ellingjord-Dale M, Vos L, Tretli S, et al. Parity, hormones and breast cancer subtypes - results from a large nested case-control study in a national screening program. Breast Cancer Res. 2017;19(1):10.
Ellingjord-Dale, M., Vos, L., Tretli, S., Hofvind, S., Dos-Santos-Silva, I., & Ursin, G. (2017). Parity, hormones and breast cancer subtypes - results from a large nested case-control study in a national screening program. Breast Cancer Research : BCR, 19(1), p. 10. doi:10.1186/s13058-016-0798-x.
Ellingjord-Dale M, et al. Parity, Hormones and Breast Cancer Subtypes - Results From a Large Nested Case-control Study in a National Screening Program. Breast Cancer Res. 2017 01 23;19(1):10. PubMed PMID: 28114999.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Parity, hormones and breast cancer subtypes - results from a large nested case-control study in a national screening program. AU - Ellingjord-Dale,Merete, AU - Vos,Linda, AU - Tretli,Steinar, AU - Hofvind,Solveig, AU - Dos-Santos-Silva,Isabel, AU - Ursin,Giske, Y1 - 2017/01/23/ PY - 2016/08/12/received PY - 2016/12/22/accepted PY - 2017/1/25/entrez PY - 2017/1/25/pubmed PY - 2017/8/8/medline KW - Breast cancer subtypes KW - Hormone therapy KW - Reproductive factors SP - 10 EP - 10 JF - Breast cancer research : BCR JO - Breast Cancer Res. VL - 19 IS - 1 N2 - BACKGROUND: Breast cancer comprises several molecular subtypes with different prognoses and possibly different etiology. Reproductive and hormonal factors are associated with breast cancer overall, and with luminal subtypes, but the associations with other subtypes are unclear. We used data from a national screening program to conduct a large nested case-control study. METHODS: We conducted a nested case-control study on participants in the Norwegian Breast Cancer Screening Program in 2006 - 2014. There was information on estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) for 4748 cases of breast cancer. Breast cancer subtypes were defined as luminal A-like (ER+ PR+ HER2-), luminal B-like (ER+ PR- HER2- or ER+ PR+/PR-HER2+), HER2-positive (ER- PR- HER2+) and triple-negative (ER- PR- HER2-). Conditional logistic regression was used to estimate odds ratios (ORs) of breast cancer associated with age at first birth, number of pregnancies, oral contraceptive use, intrauterine devices and menopausal hormone therapy. Analyses were adjusted for age, body mass index, education, age at menarche, number of pregnancies and menopausal status. RESULTS: Number of pregnancies was inversely associated with relative risk of luminal-like breast cancers (p-trend ≤0.02), and although not statistically significant, with HER2-positive (OR = 0.60, 95% CI 0.31-1.19) and triple-negative cancer (OR = 0.70, 95% CI 0.41-1.21). Women who had ≥4 pregnancies were at >40% lower risk of luminal-like and HER2-positive cancers than women who had never been pregnant. However, there was a larger discrepancy between tumor subtypes with menopausal hormone use. Women who used estrogen and progesterone therapy (EPT) had almost threefold increased risk of luminal A-like cancer (OR = 2.92, 95% CI 2.36-3.62) compared to never-users, but were not at elevated risk of HER2-positive (OR = 0.88, 95% CI 0.33-2.30) or triple-negative (OR = 0.92, 95% CI 0.43 - 1.98) subtypes. CONCLUSIONS: Reproductive factors were to some extent associated with all subtypes; the strongest trends were with luminal-like subtypes. Hormone therapy use was strongly associated with risk of luminal-like breast cancer, and less so with risk of HER2-positive or triple-negative cancer. There are clearly some, but possibly limited, etiologic differences between subtypes, with the greatest contrast between luminal A-like and triple-negative subtypes. TRIAL REGISTRATION: Not applicable. SN - 1465-542X UR - https://www.unboundmedicine.com/medline/citation/28114999/Parity_hormones_and_breast_cancer_subtypes___results_from_a_large_nested_case_control_study_in_a_national_screening_program_ L2 - https://breast-cancer-research.biomedcentral.com/articles/10.1186/s13058-016-0798-x DB - PRIME DP - Unbound Medicine ER -