Table 1:

Characteristics of the study sample

	Breast cancer cases (n=3368)
	N	%
Demographics1
Age at cancer diagnosis
65–69	840	24.9
70–74	1035	30.7
75–79	899	26.7
≥ 80	594	17.6
Race/ethnicity
Non-Hispanic White	3045	90.4
African American or Black	180	5.3
Non-White/non-Black	143	4.2
Residence at diagnosis, percent urban
0	154	4.8
1–49	218	6.8
50–99	614	19.2
100	2210	69.1
Education
High school diploma/GED or less	626	18.7
School after high school	1232	36.8
College degree or higher	1492	44.5
Body-mass index( kg/m2)
<25	1109	33.2
25 – <30	1147	34.3
>=30	1087	32.5
Smoking status
Never	1644	49.5
Past	1516	45.7
Current	158	4.8
Charlson comorbidity score3
0	2482	73.7
1	611	18.1
2+	275	8.2
Tumor characteristics
Summary Stage
Localized	2669	79.2
Regional	699	20.8
Tumor size (cm)
≤1	1358	40.3
>1–2	1285	38.2
>2–5	565	16.8
>5	64	1.9
Unknown	96	2.9
Nodal involvement
No	2667	79.2
Yes	662	19.7
Unknown	39	1.2
ER receptor
Positive	2787	82.7
Negative	426	12.6
Unknown	155	4.6
PR receptor
Positive	2399	71.2
Negative	795	23.6
Unknown	174	5.2
Her2-neu receptor
Positive	345	10.2
Negative	2367	70.3
Unknown	656	19.5
Triple negative
No	3131	93.0
Yes	237	7.0
Cancer treatment2
Chemotherapy
No	2724	80.9
Yes	644	19.1
Surgery type and radiation
Breast-conserving with no radiation	361	10.7
Breast conserving with radiation	1945	57.8
Mastectomy with no radiation	852	25.3
Mastectomy with radiation	210	6.2

¹Demographic characteristics as collected at enrollment in the Women’s Health Initiative, except as noted.

²Derived from Medicare claims data