Menopausal vasomotor symptoms and incident breast cancer risk in the Study of Women's Health Across the Nation.
Two case-control studies reported a 50 % decreased breast cancer risk among women who experienced menopausal vasomotor symptoms (VMS), but one cohort study found no association. VMS may be triggered by declining estrogen levels during menopause, whereas elevated estrogen levels have been associated with increased breast cancer risk. VMS may thus be indicative of lower susceptibility to breast cancer.



We evaluated this relationship in the longitudinal Study of Women's Health Across the Nation (SWAN), using discrete survival analysis of approximately annual data on VMS and self-reported breast cancer occurrences for up to 13 years of follow-up in 3,098 women who were pre- or early perimenopausal at enrollment.



Over an average 11.4 years of follow-up, 129 incident breast cancer cases were self-reported, and approximately 50 % of participants experienced VMS. Symptomatic women had a reduced risk of breast cancer compared to non-symptomatic women (adjusted HR 0.63, 95 % CI 0.39, 1.00). The association was stronger in the subgroup of women who fully transitioned to postmenopause during follow-up (n = 67 cases, adjusted HR 0.45, 95 % CI 0.26, 0.77).



VMS appeared to be a marker of reduced breast cancer risk. Future research is needed to understand the biology underlying this relationship.
Department of Biostatistics and Epidemiology, University of Massachusetts Amherst, 411 Arnold House, 715 North Pleasant Street, Amherst, MA, 01003, USA.
Vicki
V
Hart
Department of Biostatistics and Epidemiology, University of Massachusetts Amherst, 411 Arnold House, 715 North Pleasant Street, Amherst, MA, 01003, USA.
Susan R
SR
Sturgeon
Department of Biostatistics and Epidemiology, University of Massachusetts Amherst, 411 Arnold House, 715 North Pleasant Street, Amherst, MA, 01003, USA.
Nicholas
N
Reich
Department of Anthropology, University of Massachusetts Amherst, Amherst, MA, USA.
Lynnette Leidy
LL
Sievert
Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA.
Sybil L
SL
Crawford
Department of Public Health Sciences, School of Medicine, University of California School of Medicine, Davis, CA, USA.
Ellen B
EB
Gold
Department of Social Sciences and Health Policy, Wake Forest School of Medicine, Winston-Salem, NC, USA.
Nancy E
NE
Avis
Department of Biostatistics and Epidemiology, University of Massachusetts Amherst, 411 Arnold House, 715 North Pleasant Street, Amherst, MA, 01003, USA. kwreeves@schoolph.umass.edu.
Katherine W
KW
Reeves
D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology*; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D019584:Hot Flashes / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008593:Menopause; D008875:Middle Aged; D012306:Risk; D057566:Self Report; D013546:Sweating; D016387:Women's Health
Breast cancer; Menopause; Postmenopausal; Vasomotor symptoms
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