This field is created by the central registry. It records the source from which the consolidated information was obtained on a patient's vital status and date of last contact. Follow-up Source Central would be updated when new or more reliable information becomes available. However, when the existing date of last contact/vital status is deemed to be more reliable than newly obtained information, then neither the date of last contact/vital status nor the follow-up source central would be changed.

For central registries performing follow-up, this field could help evaluate the success rates of various methods of follow-up. When new follow-up information conflicts with the existing information, knowing the follow-up source can help resolve any discrepancies.

00	Follow-up not performed for this patient
(01-29)	File Linkages
01	Medicare/Medicaid File
02	Center for Medicare and Medicaid Services (CMS, formerly HCFA)
03	Department of Motor Vehicle Registration
04	National Death Index (NDI)
05	State Death Tape/Death Certificate File
06	County/Municipality Death Tape/ Death Certificate File
07	Social Security Administration Death Master File
08	Hospital Discharge Data
09	Health Maintenance Organization (HMO) file
10	Social Security Epidemiological Vital Status Data
11	Voter Registration File
12	Research/Study Related Linkage
29	Linkages, NOS
(30-39)	Hospitals and Treatment Facilities
30	Hospital in-patient/outpatient
31	Casefinding
32	Hospital cancer registry
33	Radiation treatment center
34	Oncology clinic
35	Ambulatory surgical center
39	Clinic/facility, NOS
(40-49)	Physicians
40	Attending physician
41	Medical oncologist
42	Radiation oncologist
43	Surgeon
48	Other specialist
49	Physician, NOS
(50-59)	Patient
50	Patient contact
51	Relative contact
59	Patient, NOS
(60-98)	Other
60	Central or Regional cancer registry
61	Internet sources
62	Hospice
63	Nursing homes
64	Obituary
65	Other research/study related sources
98	Other, NOS
99	Unknown source