Table 2.

 Relative risks compared with internal references of invasive cervical cancer and vaginal cancer among women with previous cervical intraepithelial neoplasia grade 3 (CIN 3)

Variables	Relative risk (95% CI) of cervical cancer	Relative risk (95% CI) of vaginal cancer
Age at diagnosis of CIN 3:
<20	0.49 (0.16 to 1.53)	*
20-29	0.67 (0.55 to 0.81)	2.25 (1.04 to 4.87)
30-39†	1.00 (1.00 to 1.00)	1.00 (1.00 to 1.00)
40-49	1.23 (1.03 to 1.48)	2.41 (1.31 to 4.45)
50-59	2.67 (2.16 to 3.29)	2.90 (1.47 to 5.73)
60-69	4.75 (3.63 to 6.21)	3.81 (1.77 to 8.19)
70-79	6.00 (3.88 to 9.28)	6.44 (2.71 to 15.33)
≥80	6.38 (1.58 to 25.70)	9.72 (2.15 to 44.04)
P for trend	<0.001	<0.001
Period of diagnosis:
1958-70†	1.00 (1.00 to 1.00)	1.00 (1.00 to 1.00)
1971-80	1.37 (1.27 to 1.07)	0.54 (0.33 to 0.87)
1981-90	1.76 (1.63 to 1.35)	0.78 (0.46 to 1.31)
1991-2000	1.80 (1.65 to 1.27)	0.46 (0.20 to 1.04)
P for trend	<0.001	0.007
Time since diagnosis (years):
1-<2	1.16 (0.88 to 1.54)	2.09 (0.94 to 4.65)
2-4†	1.00 (1.00 to 1.00)	1.00 (1.00 to 1.00)
5-9	1.03 (0.85 to 1.26)	0.95 (0.50 to 1.80)
10-14	0.94 (0.76 to 1.18)	0.66 (0.33 to 1.31)
15-19	0.84 (0.65 to 1.08)	0.45 (0.21 to 0.95)
20-24	0.86 (0.64 to 1.15)	0.44 (0.20 to 0.96)
≥25	0.91 (0.67 to 1.23)	0.21 (0.09 to 0.47)
P for trend	0.04	<0.001
P for interaction‡	<0.001	0.45

Result of multivariable log-linear regression, with adjustment for age at diagnosis of CIN 3, period of diagnosis, and time (years) since diagnosis and the detection of invasive cancer.

*This category was collapsed with 20-29 years owing to lack of cases.

†Reference category.

‡Interaction between period of diagnosis and time since diagnosis.