Pubertal timing and incident uterine cancer in the Sister Study cohort

Younger age at menarche is an established uterine cancer risk factor. Age at onset of breast development (thelarche) may also be relevant to uterine cancer risk. Analysis of data from the US Sister Study cohort (2003-2009; 34,152 participants; ages 35-75 years) examined associations of self-reported ages at thelarche and menarche with incident uterine cancer. During a median follow-up of 13.3 years, 445 women reported an incident uterine cancer diagnosis. Age at thelarce (HR per 1-year older 0.91; 95% CI 0.85-0.97) and menarche (0.90; 0.84-0.96) were inversely associated with uterine cancer incidence. Associations were similar in non-Hispanic Black and White women, and did not vary by relative childhood weight or BMI in adulthood. Inverse associations of thelarche and menarche were limited to women born in 1950 or later. The authors conclude that these findings suggest that younger ages at thelarche and menarche, markers of earlier and potentially prolonged exposure to estrogen in the absence of progesterone during puberty, may enhance susceptibility to uterine carcinogenesis (visual abstract).