Associations of height, body mass index, and weight gain with breast cancer risk in carriers of a pathogenic variant in BRCA1 or BRCA2: the BRCA1 and BRCA2 Cohort Consortium

Table 4 Prospective analysis of height, body mass index, weight change, and breast cancer risk, by menopausal status

Menopausal status	Premenopausal								Postmenopausal
BRCA status	BRCA1				BRCA2				BRCA1				BRCA2
BRCA status	n	BC	HR	95% CI	n	BC	HR	95% CI	n	BC	HR	95% CI	n	BC	HR	95% CI
Height, per 10 cm	1516	115	1.19	0.91–1.56	1011	51	1.32	0.92–1.90	905	112	0.97	0.73–1.30	626	67	0.95	0.68–1.31
Young-adult BMI per 5 kg/m² (continuous)	1242	96	0.78	0.52–1.16	829	40	0.82	0.49–1.36	729	89	1.06	0.73–1.53	509	56	1.00	0.76–1.30
Baseline BMI, kg/m² (categories)
< 18.5	96	2	0.25	0.58– 1.08	33	1	0.71	0.11– 4.46	25	3	0.95	0.30–3.06	9	1	1.15	0.16–8.50
18.5 to < 25 (reference)	986	83	1.0		656	38	1.0		489	56	1.0		331	29	1.0
≥25	434	30	0.89	0.57–1.39	322	12	0.59	0.30–1.15	391	53	1.21	0.81–1.82	286	37	1.13	0.68–1.89
Baseline BMI per 5 kg/m² (continuous)	1516	115	1.00	0.84–1.20	1011	51	0.92	0.66–1.28	905	112	1.20	1.02–1.42	626	67	0.97	0.81–1.17
Weight change (categories)
≥ 5 kg loss	93	6	0.76	0.34–1.75	52	2	1.40	0.23–8.65	28	4	1.67	0.61–4.61	29	6	2.53	0.97–6.58
< 5 kg loss to < 5 kg gain (reference)	506	34	1.0		324	11	1.0		183	18	1.0		121	7	1.0
≥ 5 kg gain to < 15 kg gain	438	34	1.07	0.65–1.75	301	19	2.16	0.96–4.88	288	34	1.21	0.67–2.20	194	27	1.89	0.85–4.19
≥ 15 kg gain	205	22	1.43	0.80–2.54	152	8	1.14	0.46–2.82	230	33	1.63	0.88–3.04	165	16	1.18	0.46–3.05
Weight change*, per kg (continuous)	1242	96	1.04	0.94–1.16	829	40	1.07	0.92–1.24	729	89	1.10	1.01–1.19	509	56	0.99	0.88–1.11

All analyses were adjusted for age at menarche, number of full-term pregnancies, oral hormonal contraceptive use, and hormone replacement therapy
BC breast cancer, BMI body mass index, 1.0 = reference value
*Positive values mean weight gain and negative values mean weight loss

ISSN: 1465-542X