. 2019 Mar 14;364:l803. doi: 10.1136/bmj.l803

Table 3.

Relative risk and absolute risk (cumulative risk) of familial colorectal cancer by various combinations of family history excluding half siblings

Family history constellation	Relative risk by age at diagnosis of youngest affected relative						Absolute risk
	All		<50 years		≥50 years		All		Men		Women
	No	SIR^* (95% CI)	No	SIR^* (95% CI)	No	SIR^* (95% CI)	No	LCR, % (95% CI)	No	LCR, % (95% CI)	No	LCR, % (95% CI)
0 FDR+1 SDR (excluding half siblings)	1437	1.2 (1.1 to 1.2)^†	597	1.1 (1.0 to 1.2)^†	840	1.2 (1.1 to 1.3)^†	1251	4.5 (4.2 to 4.9)^†	619	5.1 (4.6 to 5.7)^†	632	4.1 (3.6 to 4.5)^†
1 FDR+1 SDR (excluding half siblings)	277	2.2 (2.0 to 2.5)^†	156	2.4 (2.1 to 2.8)^†	121	2.0 (1.6 to 2.4)^†	253	7.5 (6.3 to 8.7)^†	129	8.3 (6.4 to 10)^†	124	6.9 (5.3 to 8.4)^†
2 FDRs+1 SDR (excluding half siblings)	48	4.8 (3.5 to 6.4)^†	37	5.6 (3.9 to7.7)^†	11	3.2 (1.6 to 5.8)^†	45	13 (8.6 to 17)^†	24	13 (7.1 to 19)^†	21	13 (6.3 to 19)^†
≥3 FDRs+1 SDR (excluding half siblings)	12	10 (5.3 to 18)^†	8	14 (6.0 to28)^†	4	6.8 (1.8 to 17)^†	11	26 (8.6 to 41)^†	6	23 (4.4 to 38)^†	5	26 (0 to 45)
0 FDR+2 SDRs (excluding half siblings)	99	1.6 (1.3 to 1.9)^†	11	1.0 (0.5 to 1.7)	88	1.7 (1.4 to 2.1)^†	96	4.2 (1.1 to 7.1)^†	43	7.2 (0.8 to 13)^†	53	1.5 (0.7 to 2.2)^†
1 FDR+2 SDRs (excluding half siblings)	32	5.1 (3.5 to 7.1)^†	17	7.5 (4.4 to 12)^†	15	3.7 (2.1 to 6.1)^†	32	6.9 (1.8 to 12)^†	18	5.0 (0.6 to 9.2)^†	14	9.3 (0 to 18)
2 FDRs+2 SDRs (excluding half siblings)	5	6.7 (2.2 to 16)^†	5	8.2 (2.7 to 19)^†	0	-	5	6.6 (0.4 to 13)^†	3	8.2 (0 to 17)	2	4.8 (0 to 11)
≥3 FDRs+2 SDRs (excluding half siblings)	0	-	0	-	0	-	0	-	0	-	0	-

FDR=first degree relative; LCR=lifetime (0-79 years) cumulative risk; SDR=second degree relative; SIR=standardised incidence ratio.

Adjusted for sex, age, calendar periods, residential areas, and socioeconomic status.

^†

Significant risks.