Mammographic density and risk of breast cancer by age and tumor characteristics

Breast Cancer Research

Table 3 Distribution of breast cancer cases from six studies by age and tumor characteristics

Tumor type	Age <55 years		Age 55 to 64 years		Age ≥65 years
Tumor type	N	%	N	%	N	%
Total controls	3,373	68.8	2,031	66.5	1,795	67.6
Total cases	1,533	31.2	1,021	33.5	860	32.4
Invasive	1,227	80.0	858	84.0	760	88.4
In situ	295	19.2	160	15.7	100	11.6
Unknown	11	0.7	3	0.3	0	0.0
Tumor characteristics
Histology
Ductal	988	80.5	654	76.2	545	71.7
Lobular	123	10.0	110	12.8	114	15.0
Mixed	65	5.3	55	6.4	51	6.7
Unknown/Other	51	4.2	39	4.6	50	6.6
Histologic grade
Well differentiated	292	23.8	248	28.9	259	34.1
Moderately differentiated	466	38.0	320	37.3	295	38.8
Poorly differentiated	342	27.9	165	19.2	134	17.6
Unknown	127	10.4	125	14.6	72	9.5
Tumor size
0.1 to 1.0 cm	378	30.8	312	36.7	279	36.7
1.1 to 2.0 cm	496	40.4	330	39.3	299	39.3
2.1+ cm	310	25.3	184	20.7	157	20.7
Unknown	43	3.5	32	3.3	25	3.3
Involvement of lymph nodes
Negative	810	66.0	610	71.1	500	65.8
Positive	347	28.3	192	22.4	148	19.5
Unknown	70	5.7	56	6.5	112	14.7
Estrogen receptor status
Negative	228	18.6	139	16.2	82	10.8
Positive	949	77.3	674	78.6	644	84.7
Borderline/Unknown	50	4.1	45	5.2	34	4.5
Progesterone receptor status
Negative	329	26.8	232	27.0	157	20.7
Positive	844	68.8	580	67.6	566	74.5
Borderline/Unknown	54	4.4	46	5.4	37	4.9
HER2 status
Negative	674	54.9	359	41.8	383	50.4
Positive	142	11.6	63	7.3	65	8.6
Borderline/Unknown	411	33.5	436	50.8	312	41.1

ISSN: 1465-542X