Table 2.

Breast cancer-specific and all-cause mortality by parity status and stratified by histologic subtype^a

	All histologies			Ductal subtype			Lobular subtype			Mixed Ductal-lobular subtype
	Cases	Events	HR (95%CI)	Cases	Events	HR (95%CI)	Cases	Events	HR (95%CI)	Cases	Events	HR (95%CI)
Parity	Breast cancer-specific mortality
Nulliparous	3046	445	1	2463	366	1	235	42	1	108	10	1
1	2502	401	1.06 (0.93 – 1.22)	2007	341	1.08 (0.93 – 1.25)	192	24	0.82 (0.48 – 1.40)	100	14	2.77 (1.02 – 7.50)
2	6469	820	0.91 (0.81 – 1.02)	5135	679	0.89 (0.78 – 1.01)	550	76	0.98 (0.65 – 1.48)	267	25	1.31 (0.54 – 3.18)
3	4815	628	0.92 (0.81 – 1.04)	3787	515	0.92 (0.80 – 1.05)	462	65	0.81 (0.54 – 1.24)	199	19	1.70 (0.65 – 4.40)
4	2790	371	0.86 (0.74 – 0.98)	2198	298	0.83 (0.71 – 0.97)	265	41	0.89 (0.56 – 1.41)	85	11	1.01 (0.33 – 3.09)
5+	2660	385	0.86 (0.74 – 0.99)	2088	311	0.85 (0.73 – 1.00)	249	37	0.70 (0.43 – 1.14)	90	9	1.93 (0.64 – 5.87)
PTrend			0.002			0.002			0.18			0.85
Parity	All-cause mortality
Nulliparous	3046	910	1	2463	737	1	235	80	1	108	22	1
1	2502	798	1.01 (0.92 – 1.11)	2007	659	1.03 (0.92 – 1.14)	192	58	0.95 (0.66 – 1.35)	100	27	1.31 (0.67 – 2.55)
2	6469	1634	0.91 (0.84 – 0.99)	5135	1325	0.90 (0.83 – 0.99)	550	141	0.91 (0.68 – 1.22)	267	43	0.76 (0.42 – 1.37)
3	4815	1281	0.90 (0.82 – 0.98)	3787	1031	0.90 (0.82 – 0.99)	462	129	0.77 (0.57 – 1.03)	199	35	0.84 (0.45 – 1.57)
4	2790	838	0.86 (0.78 – 0.95)	2198	670	0.86 (0.77 – 0.96)	265	87	0.80 (0.58 – 1.09)	85	18	0.52 (0.25 – 1.09)
5+	2660	941	0.92 (0.84 – 1.01)	2088	753	0.92 (0.83 – 1. 02)	249	85	0.83 (0.60 – 1.14)	90	21	0.84 (0.42 – 1.68)
PTrend			0.002			0.004			0.09			0.12

HR indicates hazard rate ratio; CI confidence interval

^aProportional hazards models were stratified by state of residence, year of interview and age at diagnosis and adjusted for menopausal status, BMI, hormone replacement therapy use, smoking status, mammography, time from date of diagnosis to interview and stage of disease at diagnosis.