Pre-diagnostic clinical features and blood tests in patients with colorectal cancer: a retrospective linked-data study

Marie Moullet; Garth Funston; Luke TA Mounce; Gary A Abel; Niek de Wit; Fiona M Walter; Yin Zhou

doi:10.3399/BJGP.2021.0563

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Figure 1.
Rates of recordings of each clinical feature in the 2 years leading up to diagnosis, by cancer diagnosis: a) colon cancer; b) rectal cancer. A solid vertical line indicates the most likely inflection point, shaded areas represents 95% confidence interval (red when confidence interval excludes 0, grey otherwise). Dotted vertical line represents 3 months before diagnosis. Inflection points are estimated in models adjusted for age, sex, and comorbidities. Months represent 28-day periods.

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How this fits in

Understanding pre-diagnostic patterns of relevant clinical features and abnormal blood test results in patients with colon and rectal cancer could elucidate windows of opportunity during which more timely investigations and referrals could be performed, and earlier diagnosis of cancer could be achieved. This study found that consultation rates increased in the year leading up to diagnosis for relevant clinical features such as low haemoglobin, rectal bleeding, and change in bowel habits, as well as non-specific blood tests, from as early as 9–10 months before diagnosis. These findings suggest that potential opportunities for more timely use of cancer investigations or referral exist, and could improve diagnostic pathways, expediting diagnosis and treatment for some patients with colorectal cancer.

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Box 1.

Blood markers included in this study and thresholds

Marker	Threshold (source)
Haemoglobin	<110 g/L for males, <100 g/L for females⁵
Platelets	>400 × 10⁹/L⁵
C-reactive protein	>7 mg/L¹⁵
Erythrocyte sedimentation rate	Previously defined age-and sex-specific thresholds¹⁵

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Table 1.

Population demographic characteristics, by diagnosis

	Cancer diagnosis				Total

	Colon		Rectal

Characteristic	n	%	n	%	n	%
Total	5033	100	2516	100	7549	100

Sex
Male	2624	52.1	1561	62.0	4185	55.4
Female	2409	47.9	955	38.0	3364	44.6

Age group, years
25–59	849	16.9	578	23.0	1427	18.9
60–69	1200	23.8	721	28.7	1921	25.4
70–79	1533	30.5	729	29.0	2262	30.0
≥80	1451	28.8	488	19.4	1939	25.7

Relevant comorbidities
Group 1: inflammatory bowel disease and diverticular disease	926	18.4	341	13.6	1267	16.8
Group 2: irritable bowel syndrome, coeliac, and gall bladder disease	316	6.3	102	4.1	418	5.5
Group 3: haemorrhoids	615	12.2	226	9.0	841	11.1

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Table 2.

Prevalence of clinical-feature recordings in each pre-diagnostic period

	Cancer diagnosis				Total (N = 7549)

	Colon(n = 5033)		Rectal (n = 2516)

Variable	n	%	n	%	n	%
Clinical features
Abdominal pain
0–1 year	1305	25.9	271	10.8	1576	20.9
1–2 years	262	5.2	72	2.9	334	4.4
Change in bowel habit
0–1 year	1091	21.7	787	31.3	1878	24.9
1–2 years	236	4.7	117	4.7	353	4.7
Rectal bleeding
0–1 year	584	11.6	810	32.2	1394	18.5
1–2 years	82	1.6	63	2.5	145	1.9
Constitutional symptoms
0–1 year	436	8.7	123	4.9	559	7.4
1–2 years	170	3.4	47	1.9	217	2.9
Other bowel function
0–1 year	165	3.3	57	2.3	222	2.9
1–2 years	41	0.8	17	0.7	58	0.8
Abdominal mass
0–1 year	83	1.6	21	0.8	104	1.4
1–2 years	7	0.1	5	0.2	12	0.2

Abnormal blood tests
Low haemoglobin
0–1 year	1417	28.2	231	9.2	1648	21.8
1–2 years	213	4.2	55	2.2	268	3.6
High inflammatory markers
0–1 year	1392	27.7	463	18.4	1855	24.6
1–2 years	367	7.3	127	5.0	494	6.5
High platelets
0–1 year	932	18.5	244	9.7	1176	15.6
1–2 years	142	2.8	52	2.1	194	2.6

a Abdominal mass includes codes for abdominal and rectal or perianal masses.

Supplementary Data

Supplementary material is not copyedited or typeset, and is published as supplied by the author(s). The author(s) retain(s) responsibility for its accuracy.