Completeness and accuracy of the registration of recurrences in the Swedish Colorectal Cancer Registry (SCRCR) and an update of recurrence risk in colon cancer

Figures & data

Figure 1. Validation cohort flowchart. Patients from Uppsala region (all stages) and Gävleborg region (stage I–III) were included for chart review and validation. Percentages calculated from previous block. Resected patients (Uppsala cohort) and the stage I–III cohort from Gävleborg included also non-radically operated patients but at risk for having a non-registered recurrence.

Table 1. Recurrences not registered in the registry from the two regions of non-metastatic colorectal cancer patients.

Year of diagnosis	N	Registered recurrences	% of N	Recurrences not registered	% of N
Uppsala region
2010–2014	605	126	21%	0	0%
2015–2016	298	46	15%	1	0%
2017	126	11	9%	2	2%
2018	160	9	6%	4	3%
Gävleborg region
2010–2014	630	104	17%	16^a	3%
2015–2016	272	29	11%	14	5%
2017	134	2	1%	13	10%
2018	138	1	1%	11	8%

Recurrences are stratified by year of diagnosis.

^a Seven of the recurrences were detected after the 5-year follow-up. N=total number of patients in the interval. % of N gives the ratio of N/recurrences. No censoring has been performed since the aim is to show the correctness of reporting to the registry. Data broken down further by year is available in Supplementary Table 1.

Table 2. Demographics of non-metastatic colon cancer patients in two population-based Swedish Colorectal Cancer cohorts diagnosed between 2010 and 2018.

	Total	Uppsala	Gävleborg	p Value
Sex
Male	723 (51%)	349 (51%)	374 (51%)	.96
Female	693 (49%)	333 (49%)	360 (49%)
Age
Mean (SD)	73 (±11)	72 (±12)	74 (±10)	.003
pT
T1	128 (9%)	55 (8%)	73 (10%)	.0002
T2	189 (13%)	78 (11%)	111 (15%)
T3	880 (62%)	416 (61%)	464 (63%)
T4	218 (15%)	133 (20%)	85 (12%)
Missing	1 (0%)	0 (0%)	1 (0%)
pN
N0	882 (62%)	391 (57%)	491 (67%)	.0003
N1	337 (24%)	192 (28%)	145 (20%)
N2	191 (13%)	96 (14%)	95 (13%)
Missing	6 (0%)	3 (0%)	3 (0%)
Found nodes
Mean (SD)	24 (±12)	24 (±12)	25 (±12)	.006
Missing	7 (0%)	3 (0%)	4 (1%)
Positive nodes
Mean (SD)	2 (±3)	2 (±3)	1 (±4)	.033
Missing	7 (0%)	3 (0%)	4 (1%)
Stage
1	274 (19%)	113 (17%)	161 (22%)	.0005
2	607 (43%)	278 (41%)	329 (45%)
3	528 (37%)	288 (42%)	240 (33%)
Missing	7 (0%)	3 (0%)	4 (1%)
Emergency surgery
Elective	1,200 (85%)	571 (84%)	629 (86%)	.18
Emergency	210 (15%)	111 (16%)	99 (13%)
Missing	6 (0%)	0 (0%)	6 (1%)
Obstruction
No	1,255 (89%)	595 (87%)	660 (90%)	.13
Yes	161 (11%)	87 (13%)	74 (10%)
Grade
Low grade malignancy	1,145 (81%)	551 (81%)	594 (81%)	.14
High grade malignancy	223 (16%)	99 (15%)	124 (17%)
Missing	48 (3%)	32 (5%)	16 (2%)
Lymphovascular Invasion
No	1,096 (77%)	475 (70%)	621 (85%)	<.0001
Yes	275 (19%)	187 (27%)	88 (12%)
Missing	45 (3%)	20 (3%)	25 (3%)
Perineural invasion
No	1,177 (83%)	560 (82%)	617 (84%)	.45
Yes	190 (13%)	96 (14%)	94 (13%)
Missing	49 (3%)	26 (4%)	23 (3%)
Risk factors
0	844 (60%)	379 (56%)	465 (63%)	.0004
1	364 (26%)	178 (26%)	186 (25%)
2+	208 (15%)	125 (18%)	83 (11%)
Adjuvant treatment
Stage I: no adjuvant	270 (99%)	111 (98%)	159 (99%)	1
Stage I: adjuvant	4 (1%)	2 (2%)	2 (1%)
Stage II: no adjuvant	521 (86%)	228 (82%)	293 (89%)	.014
Stage II: adjuvant	86 (14%)	50 (18%)	36 (11%)
Stage III: no adjuvant	206 (39%)	108 (38%)	98 (41%)	.47
Stage III: adjuvant	322 (61%)	180 (62%)	142 (59%)

p Value from chi-square test for categorical variables and non-parametric test for continuous variables comparing the patients from the Uppsala Region with the patients from the Gävleborg Region.

Table 3. Recurrence rates at 3 and 5 years after radical surgery in a Swedish population-based colon cancer patient cohort diagnosed between 2010 and 2018 according to whether adjuvant therapy was initiated or not.

	N	3-Year RR	Events	95% CI	N	5-Year RR	Events	95% CI
Colon cancer	Without adjuvant treatment
Stage II
Low risk	337	3%	9	1–5%	236	6%	6	3–9%
Intermediate risk	105	6%	6	1–11%	72	9%	2	3–15%
High risk	79	23%	16	12–32%	42	23%	0	12–32%
Stage III
Low risk	111	22%	21	13–29%	55	26%	3	16–35%
High risk	94	39%	31	27–50%	31	43%	2	30–54%
	With adjuvant treatment
Stage II
Low risk	19	16%	3	0–31%	14	16%	0	0–31%
Intermediate risk	21	10%	2	0–23%	16	23%	2	0–40%
High risk	46	12%	5	2–22%	31	16%	1	3–27%
Stage III
Low risk	154	14%	21	8–19%	109	18%	4	11–24%
High risk	167	39%	62	31–46%	76	41%	2	33–49%

RR: recurrence rate; 95% CI: 95% confidence interval; N: patients at risk during the interval; events: recurrences during the period.

Recurrences were calculated taking censoring into account.

Table 4. Results from unadjusted and adjusted Cox regressions for ESMO risk factors in 607 stage II colon cancer patients and 528 stage III colon cancer patients.

Variable	Level	Unadjusted			Adjusted
		HR	95% CI	p Value	HR	95% CI	p Value
Stage II (n = 607)
pT	pT4 vs. pT3	2.7	1.5–4.9	.002	1.8	0.9–3.7	.111
Emergency obstruction	Yes vs. no	2.0	1–4.1	.058	1.8	0.9–3.8	.123
Nodes	<12 vs. ≥12	0.9	0.2–3.7	.898	0.7	0.2–3	.635
Grade	High vs. low	1.0	0.5–2.2	.934	0.9	0.4–1.9	.771
Vascular invasion	Yes vs. no	3.3	1.8–5.9	<.0001	2.4	1.2–4.7	.013
Perineural invasion	Yes vs. no	3.0	1.5–5.8	.001	2.0	1–4.3	.063
Risk factors	1 vs. 0	1.8	1–3.3	.057
	2 vs. 0	4.3	2.2–8.4	<.0001
	High risk vs. not	2.9	1.7–4.9	<.0001
Stage III (n = 528)
pT	pT3 vs. pT1	2.0	0.8–5	.120	1.2	0.5–3	.722
	pT4 vs. pT1	3.6	1.5–9.1	.006	1.8	0.7–4.6	.236
pN	pN2 vs. pN1	2.8	2–3.8	<.0001	2.3	1.7–3.2	<.0001
Emergency obstruction	Yes vs. no	2.1	1.5–3	<.0001	1.9	1.3–2.7	.001
Nodes	<12 vs. ≥12	0.7	0.2–1.8	.417	0.7	0.3–1.9	.487
Grade	High vs. low	1.5	1–2.1	.037	1.2	0.8–1.8	.284
Vascular invasion	Yes vs. no	2.1	1.5–2.9	<.0001	1.6	1.1–2.3	.007
Perineural invasion	Yes vs. no	1.8	1.3–2.6	.000	1.2	0.8–1.7	.328
Risk factors	1 vs. 0	1.9	1.2–2.9	.005
	2 vs. 0	3.2	2.1–4.8	<.0001
	High risk vs. not	2.4	1.7–3.3	<.0001

HR: hazard ratio; 95% CI: 95% confidence interval.

Adjusted analyses for other risk factors and sex, age, and adjuvant treatment. Risk factors: obstruction, high grade malignancy, vascular, and/or perineural invasion. High-risk patients were either pT4 or had fewer than 12 investigated nodes.