Summary of findings 2. Outcome of follow‐up testing using a CEA threshold of 2.5 µg/L.

Month when CEA measured	per 1000 patients tested at a threshold of 2.5 µg/L					False alarm rate
	Estimated recurrences¹	Referrals for raised CEA	Cases of recurrence detected	Cases of recurrence missed	False alarms (cases investigated when cancer not present)
Follow‐up years 1 and 2: 3‐monthly CEA testing
3	19	212	16	3	196	92%
6	19	212	16	3	196	92%
9	39	224	32	7	192	86%
12	39	224	32	7	192	86%
15	37	223	30	7	193	87%
18	37	223	30	7	193	87%
21	31	219	25	6	194	89%
24	31	219	25	6	194	89%
Follow‐up years 3, 4 and 5: 6‐monthly CEA testing
30	46	229	38	8	191	83%
36	36	223	30	6	193	87%
42	27	217	22	5	195	90%
48	25	216	21	4	195	90%
54	17	211	14	3	197	93%
60	14	208	11	3	197	95%

¹Estimates are based on data reported by Sargent 2007. Three‐monthly data were unavailable, and so constant rates were assumed during each six‐month period for the first two years. Estimates are rounded.