Validation of the Gail model for predicting individual breast cancer risk in a prospective nationwide study of 28,104 Singapore women

Table 1 Distribution of Singapore Breast Cancer Screening Project cohort by risk factors in Gail model

	Total		Cases (all breast cancer)		Controls		P value
	Number	Percentage	Number	Percentage	Number	Percentage
Total	28,104	100.0	575	100.0	27,529	100.0
Age at menarche, years
≥ 14	18,237	64.9	324	56.3	17,913	65.1	< 0.001
12-13	8,952	31.9	213	37.0	8,739	31.7
< 12	915	3.3	38	6.6	877	3.2
Any breast biopsy Age at screening: ≥50 years
No	26,631	94.8	514	89.4	26,117	94.9	< 0.001
Yes	1,473	5.2	61	10.6	1,412	5.1
Number of affected first-degree relatives Age at first live birth: < 20 years
0	4,753	16.9	68	11.8	4,685	17.0	< 0.001^b
1	89	0.3	3	0.5	86	0.3
> 1	1	0.0	0	0.0	1	0.0
Number of affected first-degree relatives Age at first live birth: 20-24 years
0	10,321	36.7	149	26.3	10,172	37.0
1	216	0.8	13	2.1	203	0.7
> 1	6	0.0	2	0.3	4	0.0
Number of affected first-degree relatives Age at first live birth: 25-29 years or nulliparous
0	9,246	32.9	230	40.0	9,016	32.8
1	303	1.1	17	3.0	286	1.0
> 1	4	0.0	0	0.0	4	0.0
Number of affected first-degree relatives Age at first live birth: > 30 years
0	3,059	10.9	85	14.8	2,974	10.8
1	105	0.4	7	1.2	98	0.4
> 1	1	0.0	1	0.2	0	0.0

^aAll P values were calculated by using chi-squared test unless otherwise stated. ^bP value calculated by using Fisher exact test.

ISSN: 1465-542X