TY - JOUR

T1 - Breast cancer rate after oophorectomy

T2 - A Prospective Danish Cohort Study

AU - Koch, Trine

AU - Jørgensen, Jeanette Therming

AU - Christensen, Jane

AU - Dehlendorff, Christian

AU - Priskorn, Lærke

AU - Simonsen, Mette K.

AU - Duun-Henriksen, Anne Katrine

AU - Andersen, Zorana J.

AU - Juul, Anders

AU - Bräuner, Elvira V.

AU - Hickey, Martha

PY - 2021

Y1 - 2021

N2 - The association between oophorectomy and risk of breast cancer in the general population is uncertain. The aim of our study was to determine the breast cancer rate in women from the general population after oophorectomy (performed before/after menopause), and whether this varies by use of hormone replacement therapy (HRT), hysterectomy, body mass index (BMI) and shift work. The study included 24 409 female nurses (aged ≥45 years) participating in the Danish Nurse Cohort. Nurses were followed from cohort entry until date of breast cancer, death, emigration or end of follow-up at 31 December 2018, whichever came first. Poisson regression with log-transformed person-years as the offset examined the association between oophorectomy and breast cancer (all ages and stratified by menopausal status at time of oophorectomy). The potential modifying effect of HRT use, hysterectomy, BMI and shift work on the associations was estimated. During 502 463 person-years of follow-up, 1975 (8.1%) nurses were diagnosed with breast cancer. Bilateral oophorectomy was associated with a reduced breast cancer rate compared to nurses with preserved ovaries, adjusted rate ratio (95% confidence interval): 0.79 (0.64; 0.99). Similar associations (magnitude and direction) were detected for unilateral oophorectomy and when stratifying according to menopausal status at time of oophorectomy, but without statistical significance. Unilateral and bilateral oophorectomy is associated with a reduced breast cancer rate in women from the general population. This association is not modified by use of HRT, hysterectomy, BMI or shift work.

AB - The association between oophorectomy and risk of breast cancer in the general population is uncertain. The aim of our study was to determine the breast cancer rate in women from the general population after oophorectomy (performed before/after menopause), and whether this varies by use of hormone replacement therapy (HRT), hysterectomy, body mass index (BMI) and shift work. The study included 24 409 female nurses (aged ≥45 years) participating in the Danish Nurse Cohort. Nurses were followed from cohort entry until date of breast cancer, death, emigration or end of follow-up at 31 December 2018, whichever came first. Poisson regression with log-transformed person-years as the offset examined the association between oophorectomy and breast cancer (all ages and stratified by menopausal status at time of oophorectomy). The potential modifying effect of HRT use, hysterectomy, BMI and shift work on the associations was estimated. During 502 463 person-years of follow-up, 1975 (8.1%) nurses were diagnosed with breast cancer. Bilateral oophorectomy was associated with a reduced breast cancer rate compared to nurses with preserved ovaries, adjusted rate ratio (95% confidence interval): 0.79 (0.64; 0.99). Similar associations (magnitude and direction) were detected for unilateral oophorectomy and when stratifying according to menopausal status at time of oophorectomy, but without statistical significance. Unilateral and bilateral oophorectomy is associated with a reduced breast cancer rate in women from the general population. This association is not modified by use of HRT, hysterectomy, BMI or shift work.

KW - breast cancer

KW - hormone replacement therapy

KW - hysterectomy

KW - oophorectomy

KW - rate

U2 - 10.1002/ijc.33563

DO - 10.1002/ijc.33563

M3 - Journal article

C2 - 33729548

AN - SCOPUS:85103928781

VL - 149

SP - 585

EP - 593

JO - Acta - Unio Internationalis Contra Cancrum

JF - Acta - Unio Internationalis Contra Cancrum

SN - 0898-6924

IS - 3

ER -