Pubertal development in girls by breast cancer family history: the LEGACY girls cohort

Breast Cancer Res. 2017 Jun 8;19(1):69. doi: 10.1186/s13058-017-0849-y.


Background: Pubertal milestones, such as onset of breast development and menstruation, play an important role in breast cancer etiology. It is unclear if these milestones are different in girls with a first- or second-degree breast cancer family history (BCFH).

Methods: In the LEGACY Girls Study (n = 1040), we examined whether three mother/guardian-reported pubertal milestones (having reached Tanner Stage 2 or higher (T2+) for breast and pubic hair development, and having started menstruation) differed by BCFH. We also examined whether associations between body size and race/ethnicity and pubertal milestones were modified by BCFH. We used mother/guardian reports as the primary measure of pubertal milestones, but also conducted sensitivity analyses using clinical Tanner measurements available for a subcohort (n = 204). We analyzed cross-sectional baseline data with logistic regression models for the entire cohort, and longitudinal data with Weibull survival models for the subcohort of girls that were aged 5-7 years at baseline (n = 258).

Results: BCFH was modestly, but not statistically significantly, associated with Breast T2+ (odds ratio (OR) = 1.36, 95% confidence interval (CI) = 0.88-2.10), with a stronger association seen in the subcohort of girls with clinical breast Tanner staging (OR = 2.20, 95% CI = 0.91-5.32). In a longitudinal analysis of girls who were aged 5-7 years at baseline, BCFH was associated with a 50% increased rate of having early breast development (hazard ratio (HR) = 1.49, 95% CI = 1.0-2.21). This association increased to twofold in girls who were not overweight at baseline (HR = 2.04, 95% CI = 1.29-3.21). BCFH was not associated with pubic hair development and post-menarche status. The median interval between onset of breast development and menarche was longer for BCFH+ than BCFH- girls (2.3 versus 1.7 years), suggesting a slower developmental tempo for BCFH+ girls. Associations between pubertal milestones and body size and race/ethnicity were similar in girls with or without a BCFH. For example, weight was positively associated with Breast T2+ in both girls with (OR = 1.06 per 1 kg, 95% CI = 1.03-1.10) and without (OR = 1.14 per 1 kg, 95% CI = 1.04-1.24) a BCFH.

Conclusions: These results suggest that BCFH may be related to earlier breast development and slower pubertal tempo independent of body size and race/ethnicity.

Keywords: BMI; Breast cancer; Breast cancer family history; Menarche; Pubertal development.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Body Mass Index
  • Breast Neoplasms / epidemiology*
  • Breast Neoplasms / etiology*
  • Canada / epidemiology
  • Child
  • Child, Preschool
  • Cohort Studies
  • Female
  • Humans
  • Incidence
  • Kaplan-Meier Estimate
  • Menarche
  • Odds Ratio
  • Population Surveillance
  • Puberty*
  • Risk
  • United States / epidemiology

Supplementary concepts

  • Breast Cancer, Familial