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. 2025 Jan 9;34(1):108-116.
doi: 10.1158/1055-9965.EPI-24-0743.

Physical Activity during Adolescence and Early Adulthood and Breast Cancer Risk before Age 40 Years

Rebecca D Kehm  1 , Jeanine M Genkinger  1   2 , Julia A Knight  3   4 , Robert J MacInnis  5   6 , Yuyan Liao  1 , Shuai Li  5 , Prue C Weideman  5 , Wendy K Chung  7 , Allison W Kurian  8   9   10 , Sarah V Colonna  11 , Irene L Andrulis  12   13 , Saundra S Buys  11 , Mary B Daly  14 , Esther M John  8   9   10 , John L Hopper  5 , Mary Beth Terry  1   2
Affiliations

Physical Activity during Adolescence and Early Adulthood and Breast Cancer Risk before Age 40 Years

Rebecca D Kehm et al. Cancer Epidemiol Biomarkers Prev. .

Abstract

Background: Breast cancer incidence is increasing in women under age 40, underscoring the need for research on breast cancer risk factors for younger women.

Methods: We used data from an international family cohort (n = 26,348) to examine whether recreational physical activity (RPA) during adolescence and early adulthood is associated with breast cancer risk before age 40. The cohort includes 2,502 women diagnosed with breast cancer before age 40, including 2,408 diagnosed before study enrollment (68% within 5 years of enrollment). Women reported their average hours per week of moderate and strenuous RPA during adolescence (12-17 years) and early adulthood (25-34 years), which were converted to total age-adjusted metabolic equivalents per week and categorized into quartiles. We conducted attained age analyses until age 40 (follow-up time began at age 18) using Cox proportional hazards regression models adjusted for study center, race and ethnicity, and education.

Results: Being in the highest versus lowest quartile of RPA during adolescence and early adulthood were respectively associated with 12% [HR (95% confidence interval, or CI), 0.88 (0.78-0.98)] and 16% [HR (95% CI), 0.84 (0.74-0.95) lower breast cancer risks before age 40. Being in the highest quartile of RPA during both adolescence and early adulthood (Pearson correlation = 0.52) versus neither time point was associated with a 22% lower risk [HR (95% CI), 0.78 (0.68-0.89)].

Conclusions: Findings suggest that RPA during adolescence and early adulthood may lower breast cancer risk before age 40.

Impact: Policies promoting physical activity during adolescence and early adulthood may be important for reducing the growing burden of breast cancer in younger women.

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Conflict of interest statement

R.D. Kehm reports grants from the NCI during the conduct of the study. J.M. Genkinger reports grants from Columbia University during the conduct of the study. J.A. Knight reports grants from NIH during the conduct of the study. A.W. Kurian reports collaborative research but no funding: Ambry, Color Health, Bioreference/GeneDx, Invitae, Myriad, Foundation, Caris, TEMPUS, Merck, and Gilead. I.L. Andrulis reports grants from NIH during the conduct of the study. M.B. Daly reports grants from NCI during the conduct of the study. No disclosures were reported by the other authors.

Figures

Figure 1.
Figure 1.
HRs and 95% CIs for the association of recreational physical activity (RPA) during early adulthood with breast cancer risk before age 40 for individuals who were highly active vs. not highly active during adolescence in the full cohort, n = 26,348. A, shows HRs and CIs for individuals not in the highest quartile of adolescent RPA (Q1–Q3), whereas (B) shows results for those in the highest quartile of adolescent RPA (Q4). Quartile 1 (Q1) of early adulthood RPA serves as the reference. HRs and CIs are estimated from a multivariable Cox model, stratified by birth decade adjusted for study center, race and ethnicity, and education, and includes an interaction term between adolescent and early adulthood RPA. The overall interaction P-value was 0.21, with a one-degree-of-freedom P-value of 0.04 for Q4 vs. Q1 in early adulthood.
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References

    1. Kehm RD, Yang W, Tehranifar P, Terry MB. 40 years of change in age- and stage-specific cancer incidence rates in US women and men. JNCI Cancer Spectr 2019;3:pkz038. - PMC - PubMed
    1. Lima SM, Kehm RD, Terry MB. Global breast cancer incidence and mortality trends by region, age-groups, and fertility patterns. EClinicalMedicine 2021;38:100985. - PMC - PubMed
    1. di Martino E, Smith L, Bradley SH, Hemphill S, Wright J, Renzi C, et al. . Incidence trends for twelve cancers in younger adults—a rapid review. Br J Cancer 2022;126:1374–86. - PMC - PubMed
    1. Cathcart-Rake EJ, Ruddy KJ, Bleyer A, Johnson RH. Breast cancer in adolescent and young adult women under the age of 40 years. JCO Oncol Pract 2021;17:305–13. - PubMed
    1. Smith RA, Andrews KS, Brooks D, Fedewa SA, Manassaram-Baptiste D, Saslow D, et al. . Cancer screening in the United States, 2018: a review of current American Cancer Society guidelines and current issues in cancer screening. CA Cancer J Clin 2018;68:297–316. - PubMed