Format

Send to

Choose Destination
Int J Cancer. 2016 Sep 15;139(6):1223-30. doi: 10.1002/ijc.30167. Epub 2016 May 17.

Physical activity from menarche to first pregnancy and risk of breast cancer.

Author information

1
Division of Public Health Sciences, Department of Surgery, Washington University School of Medicine, St. Louis, MO.
2
Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA.
3
Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA.
4
Transdisciplinary Research on Energetics and Cancer (TREC) Center, University of Pennsylvania, Philadelphia, PA.
5
Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA.
6
Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA.
7
Division of Research, Kaiser Permanente Northern California, Oakland, CA.
8
Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA.
9
Alvin J. Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine, St. Louis, MO.

Abstract

Breast tissue is particularly susceptible to exposures between menarche and first pregnancy, and a longer interval between these reproductive events is associated with elevated breast cancer risk. Physical activity during this time period may offset breast cancer risk, particularly for those at highest risk with longer menarche-to-first-pregnancy intervals. We used data from 65,576 parous women in the Nurses' Health Study II free of cancer in 1989 (baseline) and recalled their leisure-time physical activity at ages 12-34 in 1997. Current activity was collected at baseline and over follow-up. Relative risks (RRs) were estimated using multivariable Cox proportional hazards regression models. Between 1989 and 2011, 2,069 invasive breast cancer cases were identified. Total recreational activity between menarche and first pregnancy was not significantly associated with the risk of breast cancer. However, physical activity between menarche and first pregnancy was associated with significantly lower breast cancer risk among women in the highest category of a menarche-to first-pregnancy interval (≥20 years; RR for the highest versus the lowest quartile = 0.73, 95% confidence interval = 0.55-0.97; Ptrend  = 0.045; Pinteraction  = 0.048). This was not observed in women with a shorter interval. Physical activity between menarche and first pregnancy was associated with a lower risk of breast cancer among women with at least 20 years between these reproductive events. This may provide a modifiable factor that women can intervene on to mitigate their breast cancer risk associated with a longer interval.

KEYWORDS:

breast cancer; early life; physical activity

PMID:
27130486
PMCID:
PMC5257171
DOI:
10.1002/ijc.30167
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Wiley Icon for PubMed Central
Loading ...
Support Center