Agreement between the Danish Cancer Registry and the Danish Colorectal Cancer Group Database

Figures & data

Table 1. Registered Danish patients with CRC in 2014–2015.

	Combination of DCRtotal and DCCGtotal		Merger of DCRDCCG and DCCGtotal
	n	%	n	%
Data source
Intersection of DCR and DCCG	9977	(85)	9214	(86)
Set difference of DCR	1331	(11)	420	(4)
Set difference of DCCG	373	(4)	1054	(10)
Total	11,681	(100)	10,688	(100)

DCR_total: all tumors registered in the Danish Cancer Registry; DCR_DCCG: patients registered in the Danish Cancer Registry that fulfill the inclusion criteria of DCCG; DCCG_total: patients registered in DCCG with residence in Denmark at time of diagnosis; Set difference of DCR: patients registered in DCR and not in DCCG; Set difference of DCCG: patients registered in DCCG and not in DCR; Intersection of DCR and DCCG: patients registered in both DCR and DCCG; Merger of DCR and DCCG: patients registered in either DCR or DCCG.

Figure 1. Definition of the patient cohort. DCR: Danish Cancer Registry; DCCG: Danish Colorectal Cancer Group; CRC: colorectal cancer. ¹Patients registered in DCCG in 2014–2015 with a Danish residence at the time of diagnosis. ²Number of tumors (C18-C20.9) of patients registered in DCR in 2014–2015 with a Danish residence at the time of diagnosis. ³Patients registered in DCR that fulfill the inclusion criteria of DCCG.

Table 2. Patients ony found in the set difference of DCR_DCCG and not in DCCG_total in 2014 and 2015 from the merger of DCR_DCCG and DCCG_total.

Registered in DPR in the study period with CRC and fulfilling the inclusion criteria of DCCG	267
Registered in DCCG before the study period	7
Registered in DPR with a tumor with a different histology that does not fulfill the inclusion criteria of DCCG	111
Possible DCO	11
Unknown in DPR or registered in DPR with a consultation, or an examination of a previous material or a premalignant disease	17
Unknown explanation	7
Total	420

CRC: colorectal cancer; DCO: death certificate only; DCCG: Danish Colorectal Cancer Group; DPR: The Danish Pathology Register.

Table 3. Patients with CRC found only in the set difference of DCCG_total and not in DCR_DCCG in 2014 and 2015 from the merger of DCR_DCCG and DCCG_total.

Registered in NPR in the study period with CRC and fulfilling the inclusion criteria in DCR	122
Registered in NPR with an incomplete registration of CRC	151
Registered in DCR with CRC in the study period, but with a different morphology code than in DCCG	360
Registered in DCR with CRC before or after the study period	377
Possible DCO	5
Registered in NPR with another cancer than CRC	1
Unknown explanation	38
Total	1054

CRC: colorectal cancer; DCO: death certificate only; DCCG: Danish Colorectal Cancer Group; DPR: The Danish Pathology Register; NPR: The Danish National Patient Registry.

Table 4. One-year Relative Survival (1-year RS) of Danish patients diagnosed with CRC in 2014 and 2015.

	ndeath	1-year RS	95% CI
DCRtotal	1934	84	(84–85)
DCRDCCG	1452	86	(85–87)
DCCGtotal	1682	85	(84–86)
Intersection of DCRDCCG and DCCGtotal^a	1317	86	(86–87)
Intersection of DCRDCCG and DCCGtotal^b	1324	87	(86–87)
Set difference of DCRDCCG	135	71	(67–77)
Set difference of DCCGtotal	358	71	(68–74)

1-RS: one year relative survival; CI: confidence interval; CRC: colorectal cancer; DCR_total: all tumors registered in the Danish Cancer Registry; DCR_DCCG: patients registered in the Danish Cancer Registry that fulfill the inclusion criteria of DCCG; DCCG_total: patients registered in DCCG with residence in Denmark at time of diagnosis; Set difference of DCR_DCCG: patients registered in DCR_DCCG and not in DCCG_total; Set difference of DCCG_total: patients registered in DCCG_total and not in DCR_DCCG; Intersection of DCR_DCCG and DCCG_total: patients registered in both DCR_DCCG and DCCG_total.

^aDCR’s date of diagnosis as date of entry.

^bDCCG’s date of diagnosis as date of entry.

Table 5. Cox Proportional Hazard models for Danish patients diagnosed with CRC in 2014 and 2015.

	ndeath	MRR^c	95% CI
DCRtotal	1934	1.00	–
DCRDCCG	1452	0.87	(0.82–0.94)
DCRtotal	1934	1.00	–
DCCGtotal	1682	0.95	(0.89–1.02)
DCRDCCG	1452	1.00	–
DCCGtotal	1682	1.09	(1.01–1.17)
Intersection of DCRDCCG and DCCGtotal^a	1317	1.00	–
Intersection of DCRDCCG and DCCGtotal^b	1324	1.01	(0.93–1.09)
Intersection of DCRDCCG and DCCGtotal^a	1317	1.00	–
Set difference of DCRDCCG	135	2.33	(1.95–2.78)
Set difference of DCCGtotal	358	2.39	(2.13–2.69)
Intersection of DCRDCCG and DCCGtotal^b	1324	1.00	–
Set difference of DCRDCCG	135	2.31	(1.93–2.75)
Set difference of DCCGtotal	358	2.37	(2.10–2.66)
Intersection of DCRDCCG and DCCGtotal^a	1317	1.00	–
DCRDCCG	1452	1.06	(0.98–1.14)
Intersection of DCRDCCG and DCCGtotal^b	1324	1.00	–
DCCGtotal	1682	1.14	(1.06–1.22)

MRR: mortality rate ratio; CI: confidence interval; CRC: colorectal cancer; DCR_total: all tumors registered in the Danish Cancer Registry; DCR_DCCG: patients registered in the Danish Cancer Registry that fulfill the inclusion criteria of DCCG; DCCG_total: patients registered in DCCG with residence in Denmark at time of diagnosis; Set difference of DCR_DCCG: patients registered in DCR_DCCG and not in DCCG_total; Set difference of DCCG_total: patients registered in DCCG_total and not in DCR_DCCG; Intersection of DCR_DCCG and DCCG_total: patients registered in both DCR_DCCG and DCCG_total.

^aDCR_DCCG date of diagnosis as date of entry.

^bDCCG_total date of diagnosis as date of entry.

^cStratified on age and gender.

Figure 2. Kaplan-Meier curves for selected groups. The fractional survival of patients with CRC as a function of time since diagnosis. DCR_total: all CRC tumors registered in the Danish Cancer Registry; DCR_DCCG: patients registered in the Danish Cancer Registry that fulfill the inclusion criteria of DCCG; DCCG_total: patients registered in DCCG with residence in Denmark at time of diagnosis. Set difference of DCCG_total: patients registered in DCCG and not in DCR.