. 2024 Dec 31;14(1):e70539. doi: 10.1002/cam4.70539

TABLE 5.

Association between asthma and incident breast cancer among 202,055 participants in the Nurses' Health Studies I and II from 1976 until 2016, and 1989 until 2015, respectively, stratified by smoking and menopausal status.

	Premenopausal women				Postmenopausal women
	Person‐years	No. of cases	Multivariable‐adjusted HR		Person‐years	No. of cases	Multivariable‐adjusted HR
	Person‐years	No. of cases	HR	95% CI	Person‐years	No. of cases	HR	95% CI
NHS, asthma versus no ^a
All participants	159,404	406	0.98	0.70–1.37	1,974,748	6910	0.92	0.85–0.99
According to smoking status
Never‐smokers	77,123	193	0.84	0.50–1.41	880,861	2951	0.91	0.81–1.03
Ever smokers	82,065	212	1.13	0.72–1.77	1,089,980	3943	0.92	0.84–1.02
P‐interaction			0.36				0.98
NHS II, asthma versus no ^a
All participants	1,275,717	1699	0.86	0.73–1.03	780,590	1604	0.89	0.77–1.04
According to smoking status
Never‐smokers	863,193	1099	0.78	0.63–0.98	483,311	944	0.77	0.63–0.94
Ever smokers	410,959	597	1.01	0.76–1.35	296,454	660	1.11	0.90–1.38
P‐interaction			0.07				0.09
Meta‐analysis, asthma versus no ^a
All participants	1,440,419	2110	0.89	0.76–1.04	2,941,075	8727	0.91	0.86–0.98
According to smoking status
Never‐smokers	942,858	1296	0.79	0.64–0.97	1,445,459	4638	0.85	0.73–1.00
Ever smokers	495,158	809	1.05	0.82–1.33	1,467,037	4705	0.99	0.83–1.18
P‐interaction			0.08				0.22

Note: Multivariable models were adjusted for age, race, family history of breast cancer in first‐degree relative(s), history of benign breast disease, height, body mass index at age 18, current BMI, age at menarche, parity, age at first birth, use of postmenopausal hormones, moderate and vigorous physical activity, and alcohol consumption.

Abbreviations: CI, confidence interval; HR, hazard ratio; NHS, nurses' health study.

^{^a}

Modeled as an updated exposure during follow‐up. Observations with missing values for height (0.1%) were excluded from analyses (multivariable‐adjusted models). Observations with missing values for other variables were included in the model as a “missing” category. Vales with statistical significance at the 0.05‐level are highlighted in bold.