Table 5.

Age at attained height in relation to breast cancer incidence, stratified by age at menarche, 1999–2015.

Age at menarche ≥14 years
		All invasive breast cancer (n=205)			ER+ breast cancer (n=118)			ER- breast cancer (n=60)
	Person-years	Cases	HR	95% CI	Cases	HR	95% CI	Cases	HR	95% CI
Age at attained height (years)
>17	30,697	49	1.0	Ref	26	1.0	Ref	13	1.0	Ref
13–17	84,657	156	1.15	(0.83, 1.59)	92	1.26	(0.81, 1.97)	47	1.29	(0.69, 2.41)
Age at menarche 12–13 years
		All invasive breast cancer (n=609)			ER+ breast cancer (n=371)			ER- breast cancer (n=181)
	Person-years	Cases	HR	95% CI	Cases	HR	95% CI	Cases	HR	95% CI
Age at attained height (years)
>17	58,808	111	1.0	Ref	69	1.0	Ref	31	1.0	Ref
13–17	256,149	462	0.94	(0.76, 1.15)	277	0.89	(0.68, 1.16)	140	1.03	(0.70, 1.52)
<13	14,737	36	1.21	(0.83, 1.76)	25	1.32	(0.83, 2.09)	10	1.25	(0.61, 2.56)
Age at menarche ≤11 years
		All invasive breast cancer (n=347)			ER+ breast cancer (n=207)			ER- breast cancer (n=112)
	Person-years	Cases	HR	95% CI	Cases	HR	95% CI	Cases	HR	95% CI
Age at attained height (years)
>17	23,012	41	1.0	Ref	27	1.0	Ref	11	1.0	Ref
13–17	128,498	225	0.95	(0.68, 1.33)	130	0.85	(0.56, 1.29)	77	1.18	(0.63, 2.23)
<13	33,561	81	1.23	(0.84, 1.79)	50	1.15	(0.72, 1.85)	24	1.35	(0.66, 2.78)

ER, estrogen receptor; HR, hazard ratio; CI, confidence interval Multivariable HRs are adjusted for age, questionnaire cycle, family history of breast cancer, current BMI (continuous, kg/m²), parity/age at first birth, oral contraceptive use, menopausal status, estrogen plus progestin use, education, and adult height.