The Protective Effect of Parity in Hormone Receptor‐Positive, Ki‐67 Expressing Breast Cancer

Lee, Se Kyung; Kim, Seok Won; Han, Sun-Hee; Kil, Won Ho; Lee, Jeong Eon; Nam, Seok Jin

doi:10.1007/s00268-014-2468-4

Cited by 4 publications

(9 citation statements)

References 52 publications

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“…Our observation of an inverse association between parity and luminal A-like breast cancer is consistent with the vast majority of studies as summarized in the recent systematic review of 38 studies [47] and the more recent studies that were not included in the review [7, 8, 10, 48–51]. The results for luminal B breast cancer have been less clear, with studies finding a protective or increased effect, or no effect of parity [47–50].…”

Section: Discussionsupporting

confidence: 90%

“…In the current study, parity was associated with a decreased risk of both luminal B-like subtypes. This is consistent with four out of six studies included in the systematic review [47] and three of the more recent studies [48–50]. Two of these recent studies had information on Ki-67 [48, 49].…”

Section: Discussionsupporting

confidence: 85%

“…This is consistent with four out of six studies included in the systematic review [47] and three of the more recent studies [48–50]. Two of these recent studies had information on Ki-67 [48, 49]. When we added grade to the luminal A-like and luminal B-like subtypes, the parity results remained largely the same.…”

Section: Discussionsupporting

confidence: 83%

“…In contrast, in the systematic review of 38 studies [47] they used a wider definition of luminal A (ER+ and/or PR+ and HER2-), and only one luminal B subtype (ER+ and/or PR+ HER2+). Some studies have also added on Ki67 to the definition of luminal B [40, 48, 49], which may give a more precise definition of luminal B, although Ki67 is notoriously difficult to assess [55]. Although our luminal A results were much in line with previous studies, there were some slight differences between our study and previous studies of luminal B, as discussed below.…”

Section: Discussionsupporting

confidence: 79%

“…This is consistent with the findings in the Nurses’ Health Study [49], but inconsistent with a case–control study from the Breast Cancer Family Registry [50] and a Korean cohort study [48], which reported that parity was associated with an increased risk of the HER2-positive subtype. One of these latter studies included very few women with HER2-positive breast cancer and both studies included younger women than the current study.…”

Section: Discussionsupporting

confidence: 70%

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Parity, hormones and breast cancer subtypes - results from a large nested case-control study in a national screening program

et al. 2017

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BackgroundBreast 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.MethodsWe 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.ResultsNumber 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.ConclusionsReproductive 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 registrationNot applicable.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 85%

Section: Discussionsupporting

confidence: 83%

Section: Discussionsupporting

confidence: 79%

Section: Discussionsupporting

confidence: 70%

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Parity, hormones and breast cancer subtypes - results from a large nested case-control study in a national screening program

et al. 2017

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Estrogens and the risk of breast cancer: A narrative review of literature

Al-Shami,

Awadi,

Khamees

et al. 2023

Heliyon

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Number of Risky Lifestyle Behaviors and Breast Cancer Risk

Ellingjord-Dale

Vos

Hjerkind

et al. 2018

JNCI Cancer Spectrum

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Background Lifestyle factors are associated with overall breast cancer risk, but less is known about their associations, alone or jointly, with risk of specific breast cancer subtypes. Methods We conducted a case–control subjects study nested within a cohort of women who participated in the Norwegian Breast Cancer Screening Program during 2006–2014 to examine associations between risky lifestyle factors and breast cancer risk. In all, 4402 breast cancer cases subjects with information on risk factors and hormone receptor status were identified. Conditional logistic regression was used to estimate odds ratios (ORs), with 95% confidence intervals (CIs), in relation to five risky lifestyle factors: body mass index (BMI) of 25 kg/m² or greater, three or more glasses of alcoholic beverages per week, ever smoking, fewer than four hours of physical activity per week, and ever use of menopausal hormone therapy. Analyses were adjusted for education, age at menarche, number of pregnancies, and menopausal status. All statistical tests were two-sided. Results Compared with women with no risky lifestyle behaviors, those with five had 85% (OR = 1.85, 95% CI = 1.42 to 2.42, Ptrend < .0001) increased risk of breast cancer overall. This association was limited to luminal A–like (OR = 2.20, 95% CI = 1.55 to 3.12, Ptrend < .0001) and luminal B–like human epidermal growth factor receptor 2 (HER2)–positive (OR = 1.66, 95% CI = 0.61 to 4.54, Ptrend < .004) subtypes. Number of risky lifestyle factors was not associated with increased risk of luminal B–like HER2-negative, HER2-positive, or triple-negative subtypes (Ptrend > .18 for all). Conclusions Number of risky lifestyle factors was positively associated with increased risk for luminal A–like and luminal B–like HER2-positive breast cancer.

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The Protective Effect of Parity in Hormone Receptor‐Positive, Ki‐67 Expressing Breast Cancer

Cited by 4 publications

References 52 publications

Parity, hormones and breast cancer subtypes - results from a large nested case-control study in a national screening program

Parity, hormones and breast cancer subtypes - results from a large nested case-control study in a national screening program

Estrogens and the risk of breast cancer: A narrative review of literature

Number of Risky Lifestyle Behaviors and Breast Cancer Risk

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