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

ABSTRACT:

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.

SUBMITTER: Terry MB 

PROVIDER: S-EPMC5465536 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature