. 2008 Apr 30;10(2):R38. doi: 10.1186/bcr2089

Table 4.

Association between nonsteroidal anti-inflammatory drug (NSAID) use and breast cancer by estrogen receptor status, National Institutes of Health–AARP Study

	Estrogen receptor-positive					Estrogen receptor-negative

NSAID use	Number of cancers	Person-years	Relative risk^a	95% confidence interval	P value for trend	Number of cancers	Person-years	Relative risk^a	95% confidence interval	P value for trend
Aspirin use^b
Never	493	280,706	1.00 (referent)		0.06	88	279,308	1.00 (referent)		0.54
<1/week	464	262,491	0.98	0.86 to 1.11		93	261,137	1.09	0.81 to 1.47
1–6/week	243	131,724	1.00	0.86 to 1.17		42	131,022	1.01	0.70 to 1.47
1+/day	223	143,476	0.84	0.71 to 0.98		52	142,852	1.14	0.81 to 1.62
Nonaspirin NSAID use^b
Never	541	325,816	1.00 (referent)		0.86	108	324,250	1.00 (referent)		0.64
<1/week	466	258,767	1.04	0.92 to 1.18		96	257,460	1.08	0.81 to 1.43
1–6/week	230	124,804	1.07	0.92 to 1.26		36	124,115	0.85	0.58 to 1.25
1+/day	186	107,763	0.98	0.83 to 1.16		36	107,241	0.97	0.66 to 1.42

The threshold for a positive estrogen receptor was ≥10 fmol receptor/mg total protein. ^aAdjusted for age (continuous), race, age at first birth, hormone therapy use, number of breast biopsies, alcohol intake, history of hypertension, and family history of breast cancer in first-degree relative. ^bThese models also include terms for frequency of use of opposite NSAID type.