Table 2.

Characteristics of GENESIS participants

Characteristics	Cases N = 1,552		Controls N = 1,363
	No.	%	No.	%
Birth cohort
≤1945	488	31.4	294	21.6
1946–59	797	51.4	706	51.8
≥1960	267	17.2	363	26.6
Age at censoring, years
Mean (sd)	50.2 (9.3)		55.8 (9.9)
≤45	513	33.1	201	14.8
46–50	336	21.7	197	14.5
51–60	473	30.5	485	35.6
>60	230	14.8	480	35.2
Education level
Intermediate/high	780	50.3	916	67.2
Basic	714	46.0	434	31.8
Not graduated	58	3.7	12	0.9
Missing	0	0.0	1	0.1
Body mass index
18.5–24.9	1,019	65.6	869	63.8
<18.5	69	4.5	32	2.3
≥25 and <30	341	22.0	345	25.3
≥30	120	7.7	117	8.6
Missing	3	0.2	0	0.0
Smoking
No	832	53.6	680	49.9
Current	159	10.2	158	11.6
Past	550	35.4	514	37.7
Missing	11	0.7	11	0.8
Number of full term pregnancies
≥2	445	28.7	411	30.2
1–2	921	59.3	763	56.0
0	185	11.9	187	13.7
Missing	1	0.1	2	0.1
Age at first full-term pregnancy, years
<20	179	11.5	102	7.5
20–24	628	40.5	531	39.0
25–29	393	25.4	392	28.8
≥30	165	10.6	149	10.9
No full-term pregnancy	185	11.9	187	13.7
Missing	2	0.1	2	0.1
Family history of breast cancera
None	427	27.5	959	70.4
1st degree	818	52.7	187	13.7
Only 2nd degree	307	19.8	216	15.9
Missing	0	0.0	1	0.1
Tumor estrogen receptors (ER)
ER+	818	52.7
ER-	168	10.8
Missing	566	36.5
Gene groupb
Group “Low”
0	723	46.6	721	52.9
> 1	274	17.7	441	32.4
Group “No Effect”
0	575	37.1	659	48.4
>1	422	27.2	503	36.9
Group “High”
0	422	27.2	667	48.9
>1	575	37.1	495	36.3
Missing	555	35.8	201	14.8

^aExcluding one affected sister per index case, “none” means no history of BC for controls or no additional BC case in the family for cases; “1st degree” means 1st degree family history for controls or additional 1st degree relative for cases and “2nd degree” means only 2nd degree family history for controls or only additional 2nd degree family history for cases

^bIndividuals carrying at least one variant in one of the Gene Groups: Group “Low” (OR<0.9); Group “No Effect” (0.9≤OR≤1.1); Group “High” (OR>1.1)