Circulating prolactin and breast cancer risk among pre- and postmenopausal women in the EPIC cohort

• BACKGROUND: Experimental and epidemiological evidence suggests that prolactin might play a role in the etiology of breast cancer. We analyzed the relationship of pre-diagnostic circulating prolactin levels with the risk of breast cancer by menopausal status, use of postmenopausal hormone replacement therapy (HRT) at blood donation, and by estrogen and progesterone receptor-status of the breast tumors. METHODS: Conditional logistic regression was used to analyze the data from a case-control study nested within the prospective European EPIC cohort, including 2250 invasive breast cancer and their matched control subjects. RESULTS: Statistically significant heterogeneity in the association of prolactin levels with breast cancer risk between women who were either pre- or postmenopausal at the time of blood donation was observed (Phet=0.04). Higher serum levels of prolactin were associated with significant increase in risk of breast cancer among postmenopausal women (ORQ4-Q1=1.29 [95%CI 1.05-1.58], Ptrend=0.09); however this increase in risk seemed to be confined to women who used postmenopausal HRT at blood donation (ORQ4-Q1=1.45 [95%CI 1.08-1.95], Ptrend=0.01), whereas no statistically significant association was found for the non-users of HRT (ORQ4-Q1 =1.11 [95%CI 0.83-1.49], Ptrend=0.80) (Phet=0.08). Among premenopausal women, a statistically non-significant inverse association was observed (ORQ4-Q1 =0.70 [95%CI 0.48-1.03], Ptrend=0.16). There was no heterogeneity in the prolactin-breast cancer association by hormone receptor status of the tumor. CONCLUSION: Our study indicates that higher circulating levels of prolactin among the postmenopausal HRT users at baseline may be associated with increased breast cancer risk.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Kirurgi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Surgery (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Cancer och onkologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cancer and Oncology (hsv//eng)

Nyckelord

breast cancer. prolactin levels. hormone replacement therapy. estrogen receptor. progesterone receptor. prospective cohort

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