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Erschienen in: BMC Gastroenterology 1/2022

Open Access 01.12.2022 | Research

Homogeneous and heterogeneous risk and prognostic factors for lung metastasis in colorectal cancer patients

verfasst von: Hongmei Wang, Xuefeng Shan, Min Zhang, Kun Qian, Zhengze Shen, Weiying Zhou

Erschienen in: BMC Gastroenterology | Ausgabe 1/2022

Abstract

Background

The lung is one of the most frequent distant metastasis sites in colorectal cancer (CRC) patients; however, lung metastasis risk and prognostic factors have not been comprehensively elucidated. This study aimed to identify the homogeneous and heterogeneous lung metastasis risk and prognostic factors in CRC patients using the Surveillance, Epidemiology, and End Results (SEER) database.

Methods

CRC patients registered in the SEER database between 2010 and 2016 were included to analyse risk factors for developing lung metastasis by using univariable and multivariable logistic regression. Patients diagnosed between 2010 and 2015 were selected to investigate prognostic factors for lung metastasis by conducting Cox regression. Kaplan–Meier analysis was used to estimate overall survival outcomes.

Results

A total of 10,598 (5.2%) patients with synchronous lung metastasis were diagnosed among 203,138 patients with CRC. The median survival time of patients with lung metastasis was 10.0 months (95% CI 9.6–10.5 months). Older age, unmarried status, uninsured status, poor histological differentiation, more lymphatic metastasis, CEA positivity, liver metastasis, bone metastasis and brain metastasis were lung metastasis risk and prognostic factors. Black patients and those with left colon, rectum, and stage T4 disease were more likely to develop lung metastasis, while patients with right colon cancer and no surgical treatment of the primary tumour had poor survival outcomes.

Conclusion

The incidence of lung metastasis in CRC patients was 5.2%. CRC patients with lung metastasis exhibited homogeneous and heterogeneous risk and prognostic factors. These results are helpful for clinical evaluation and individual treatment decision making.
Hinweise

Supplementary Information

The online version contains supplementary material available at https://​doi.​org/​10.​1186/​s12876-022-02270-5.
Hongmei Wang and Xuefeng Shan contributed equally to this work and should both be considered first authors
A correction to this article is available online at https://​doi.​org/​10.​1186/​s12876-022-02306-w.

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Abkürzungen
CEA
Carcinoembryonic antigen
CRC
Colorectal cancer
NCI
National Cancer Institute
SEER
Surveillance, Epidemiology, and End Results
SD
Standard deviation
SPSS
Statistical Package for the Social Sciences

Introduction

Colorectal cancer (CRC) has become the third most commonly diagnosed cancer worldwide and is the second leading cause of cancer-related death [1]. Patients with localized stage CRC commonly have a 90% 5-year survival rate; however, the survival rate worsens when the cancer spreads to distant organs [2, 3]. The lung is one of the most common distant metastasis sites in CRC patients. It has been reported to be the second most common metastatic site [3, 4]. Previous studies revealed that the incidence of lung metastasis in CRC patients ranges from 2.40 to 11.0% [5, 6]. Early detection of the high-risk population susceptible to lung metastasis is important for clinical decision-making. Chest CT, 18F-FDG-PET/CT, puncture biopsy through the wall of the chest, and bronchoscopy are commonly applied for the detection of lung metastasis [7, 8]. However, these examinations commonly involve exposure to radioactivity and are invasive and expensive, increasing the economic burden on patients. Therefore, it is necessary to identify risk factors to improve lung metastasis screening in CRC patients.
CRC patients with lung metastasis usually have poor survival outcomes. A previous study revealed that the 1-year cause-specific survival rate of CRC patients with and without lung metastasis was 55.5% and 90.2%, respectively, which was worse than that of patients with liver metastasis [3]. CRC patients with different pathological or clinical characteristics usually show different prognoses. Although some studies have investigated the risk factors for distant metastases (such as liver metastasis) in CRC, the lung metastasis risk and prognostic factors are still unclear [6, 9], and homogeneous and heterogeneous lung metastasis risk and prognostic factors have not been explored. Identifying these specific factors associated with lung metastasis will help clinicians identify high-risk patients.
The purpose of this study was to analyse the risk factors for lung metastasis and estimate the lung metastasis-associated prognosis in patients newly diagnosed with CRC based on data from the Surveillance, Epidemiology, and End Results (SEER) database. We further identified the heterogeneous and homogeneous risk and prognostic factors.

Methods

Population

In this population-based study, CRC patient data were acquired from a US National Cancer Institute (NCI) open public database, the SEER database. SEER*Stat version 8.3.5 (https://​seer.​cancer.​gov/​seerstat/​) (Information Management Service, Inc. Calverton, MD, USA) was used to generate the patient list. CRC patients diagnosed with lung metastasis between 2010 and 2016 were included in this study. Patients who were diagnosed at autopsy or via a death certificate were excluded. Patients with unspecified follow-up, a primary tumour outside of the colorectal region, and unavailable lung metastasis information were excluded. A flowchart showing the patient inclusion and exclusion process is presented in Fig. 1. Patients newly diagnosed with CRC between 2010 and 2016 were used to analyse lung metastasis risk factors, and patients diagnosed from 2010 to 2015 with a follow-up of at least 1 year were used to investigate the overall survival rate after lung metastasis.

Statistical analysis

This study included the following variables: age (< 50, 51–60, 61–70, 71–80, 81–90, ≥ 91); sex (male and female); race (white, black, other (American Indian/Alaska Native and Asian or Pacific Islander); marital status (unmarried and married); insurance status (uninsured and insured); site of primary tumour (left colon, right colon and rectum); histological types (Grade I, Grade II, Grade III, Grade IV); N stage (N0, N1, N2); T stage (T1, T2, T3, T4); carcinoembryonic antigen (CEA) (negative, positive); without or with liver metastasis; without or with bone metastasis; without or with brain metastasis; and surgical treatment for the primary cancer (yes or no).
Quantitative data are presented as the mean ± standard deviation (SD), and categorical data are described as numbers and percentages (N, %). Univariate and multivariate logistic regression were used to identify the factors associated with synchronous lung metastasis. The Kaplan–Meier method was used to estimate overall survival outcomes. Univariate and multivariate Cox regression analyses were conducted to identify potentially associated prognostic factors. Statistically significant levels were two-tailed and set at P < 0.05. Statistical analyses were conducted with the IBM Statistical Package for the Social Sciences (SPSS) version 23.0 software package for Windows (SPSS, Inc., Chicago, IL, USA). MedCalc 18.0 was used to generate survival curves.

Results

Patient characteristics

A total of 203,138 CRC patients were initially identified between 2010 and 2016. Of these patients, 10,598 (5.2%) patients were initially diagnosed with lung metastasis, and 192,540 (94.8%) patients were without lung metastasis. The mean age of all patients was 64.88 ± 14.32 years. A total of 105,727 (52.0%) patients were male. A total of 51.3% were married (N = 104,171). Over half of the patients were white (76.7%, N = 155,877). Most patients were insured (83.0%, N = 168,577). Regarding the site of the primary tumour, 40.3% (N = 81,903) of cancers were located in the right colon, 33.3% (N = 67,565) were in the left colon, and 23.5% (N = 47,660) were in the rectum. Most CRC patients were diagnosed at grade III (59.1%, N = 111,971), N0 (58.5%, N = 118,929) and stage T3 (41.7%, N = 84,747). The detailed demographic and clinical characteristics are displayed in Table 1.
Table 1
Logistic regression for characteristics to develop initial lung metastasis in patients with colorectal cancer (diagnosed 2010–2016)
Subject characteristics
Patients’ No. of CRC (2010–2016)
(N = 203,138)
Univariable analysis
Multivariable analysisa
LM
Entire cohort
%
OR [95% CI]
P value
OR [95% CI]
P value
Age(years)
       
 ≤ 50
1587
31,717
5.0
1 (Reference)
1.00
1 (Reference)
1.00
51–60
2517
46,551
5.4
1.09 (1.02–1.16)
0.013
1.11 (1.03–1.19)
0.007
61–70
2828
51,891
5.6
1.09 (1.03–1.17)
0.005
1.24 (1.16–1.34)
< 0.001
71–80
2088
40,878
5.1
1.02 (0.96–1.09)
0.525
1.34 (1.24–1.45)
< 0.001
81–90
1319
27,329
4.8
0.96 (0.89–1.04)
0.321
1.24 (1.14–1.36)
< 0.001
 ≥ 91
259
4772
5.4
1.09 (0.95–1.25)
0.213
1.13 (0.96–1.32)
0.132
Sex
       
Female
4855
97,411
5.0
1 (Reference)
1.00
1 (Reference)
1.00
Male
5743
105,727
5.4
1.10 (1.05–1.14)
< 0.001
0.93 (0.84–1.03)
0.142
Race
       
White
7795
155,877
5.0
1 (Reference)
1.00
1 (Reference)
1.00
Black
1702
25,423
6.7
1.36 (1.29–1.44)
< 0.001
1.12 (1.05–1.19)
0.001
Othersb
1078
19,755
5.5
1.10 (1.03–1.17)
0.006
1.09 (1.01–1.18)
0.022
Unknown
23
2083
1.1
0.21 (0.14–0.32)
< 0.001
0.33 (0.21–0.50)
< 0.001
Marital status
       
Unmarriedc
5136
85,861
6.0
1 (Reference)
1.00
1 (Reference)
1.00
Married
4884
104,171
4.7
0.77 (0.74–0.80)
< 0.001
0.91 (0.87–0.95)
< 0.001
Unknown
578
13,106
4.4
0.73 (0.66–0.79)
< 0.001
0.93 (0.84–1.03)
0.139
Insurance status
       
Insured
8087
168,577
4.8
1 (Reference)
1.00
1 (Reference)
1.00
Uninsured
589
6818
8.6
1.48 (1.40–1.56)
< 0.001
1.11 (1.05–1.18)
0.001
Any Medic aid
1922
27,743
6.9
1.88 (1.72–2.05)
< 0.001
1.35 (1.22–1.50)
< 0.001
Site
       
Right colon
3107
81,903
3.8
1 (Reference)
1.00
1 (Reference)
1.00
Left colon
3568
67,565
5.3
1.41 (1.35–1.49)
< 0.001
1.23 (1.21–1.35)
< 0.001
Rectum
2898
47,660
6.1
1.64 (1.56–1.73)
< 0.001
1.96 (1.84–2.08)
< 0.001
Unknown
1025
6010
17.1
5.22 (4.83–5.63)
< 0.001
1.32 (1.20–1.45)
< 0.001
Histological grade
       
Grade I
440
20,942
2.1
1 (Reference)
1.00
1 (Reference)
1.00
Grade II
4796
119,971
4.0
1.94 (1.76–2.14)
< 0.001
1.35 (1.21–1.50)
< 0.001
Grade III
1377
26,680
5.2
2.54 (2.27–2.83)
< 0.001
1.25 (1.10–1.40)
< 0.001
Grade IV
224
5430
4.1
2.01 (1.70–2.36)
< 0.001
1.12 (0.93–1.34)
0.229
Unknown
3761
30,115
12.5
6.65 (6.01–7.35)
< 0.001
1.87 (1.67–2.09)
< 0.001
Lymphatic metastasis
       
N0
3631
118,929
3.1
1 (Reference)
1.00
1 (Reference)
1.00
N1
3435
49,501
6.9
2.37 (2.26–2.48)
< 0.001
1.74 (1.64–1.85)
< 0.001
N2
1609
25,083
6.4
2.18 (2.05–2.31)
< 0.001
1.61 (1.49–1.74)
< 0.001
Unknown
1923
9625
20.0
7.93 (7.47–8.42)
< 0.001
1.58 (1.47–1.70)
< 0.001
T stage
       
T1
1121
37,387
3.0
1 (Reference)
1.00
1 (Reference)
1.00
T2
175
22,697
0.8
0.25 (0.21–0.30)
< 0.001
0.36 (0.30–0.42)
< 0.001
T3
2627
84,747
3.1
1.04 (0.96–1.11)
0.343
0.74 (0.68–0.80)
< 0.001
T4
2218
30,766
7.2
2.51 (2.34–2.71)
< 0.001
1.16 (1.07–1.27)
0.001
Unknown
4457
27,541
16.2
6.25 (5.84–6.68)
< 0.001
1.80 (1.66–1.94)
< 0.001
CEA
       
Negative
899
57,688
1.6
1 (Reference)
1.00
1 (Reference)
1.00
Positive
6325
53,812
11.8
8.41 (7.84–9.03)
< 0.001
2.40 (2.22–2.59)
< 0.001
Unknown
3374
91,638
3.7
2.42 (2.24–2.60)
< 0.001
1.39 (1.28–1.51)
< 0.001
Liver metastasis
       
No
2863
172,420
1.7
1 (Reference)
1.00
1 (Reference)
1.00
Yes
7608
30,258
25.1
19.89 (19.02–20.81)
< 0.001
9.13 (8.66–9.62)
< 0.001
Unknown
127
460
27.6
22.59 (18.35–27.8)
< 0.001
4.95 (3.83–6.40)
< 0.001
Bone metastasis
       
No
9158
199,953
4.6
1 (Reference)
1.00
1 (Reference)
1.00
Yes
1089
2454
44.4
16.62 (15.31–18.05)
< 0.001
3.53 (3.21–3.88)
< 0.001
Unknown
351
731
48.0
19.24 (16.62–22.28)
< 0.001
2.32 (1.80–2.99)
< 0.001
Brain metastasis
       
No
9899
201,765
4.9
1 (Reference)
1.00
1 (Reference)
1.00
Yes
299
566
52.8
21.71 (18.38–25.63)
< 0.001
8.53 (6.94–10.48)
< 0.001
Unknown
400
807
49.6
19.05 (16.57–21.90)
< 0.001
2.45 (1.94–3.10)
< 0.001
CEA, carcinoembryonic antigen; CRC, colorectal cancer; CI, confidence interval; LM, lung metastasis; NA, not available; OR, odds ratios
aAdjusted for age, sex, race, marital status, insurance status, site, histological grade, lymphatic metastasis, T stage, CEA, liver metastasis, bone metastasis, and brain metastasis
bIncludes American Indian/Alaska Native and Asian or Pacific Islander
cIncludes single, separated, widowed, and divorced

Risk factors for developing lung metastasis

The univariate logistic regression analysis showed that age, sex, race, marital status, insurance status, primary site, histological grade, lymphatic metastasis, T stage, CEA, liver metastasis, bone metastasis and brain metastasis were all correlated with the occurrence of lung metastasis. The multivariate logistic regression confirmed that older age, black race, unmarried status, uninsured status, site, poor histological differentiation, more lymphatic metastasis, T4/T1 stage, CEA positivity and liver metastasis, bone metastasis and brain metastasis were associated with lung metastasis (see Table 1). Only sex was not significantly associated with lung metastasis. After excluding stage T1 and stage T2 CRC patients, there were only 143,054 patients remaining. Univariate and multivariate logistic regression analyses were then performed, which revealed that most of the factors were still risk factors for metastasis, and only sex was not significantly associated with lung metastasis. The results are shown in the Additional file 1: Table S1. These data are consistent with the results obtained when stage T1 and stage T2 CRC patients were not excluded (see Table 1).

Survival estimation and prognostic factors for lung metastasis

A total of 8,867 CRC patients diagnosed with lung metastasis between 2010 and 2015 were included to estimate survival and identify prognostic factors. The median survival of CRC patients with lung metastasis was 10.0 months (95% CI 9.6–10.5 months). The 1-year, 3-year, and 5-year survival rates for lung metastasis patients were 44.3%, 13.5%, and 5.2%, respectively. When the cancers were located in the right colon or had poorly differentiated grade, were CEA positive, or involved different metastatic organs, the median survival of lung metastasis patients was reduced (see Table 2). CRC patients with lung metastasis who received surgery had longer median survival times than those who did not have surgery (19.0 months vs. 7.0 months, P < 0.001). Kaplan–Meier analysis was performed for CRC patients with lung metastasis (Fig. 2A, overall). The overall survival outcomes of patients stratified by age (Fig. 2B), sex (Fig. 2C), race (Fig. 2D), marital status (Fig. 2E), insurance status (Fig. 2F), primary site (Fig. 2G), grade (Fig. 2H), lymphatic metastasis (Fig. 2I), T stage (Fig. 2J), CEA (Fig. 2K), liver metastasis (Fig. 2L), bone metastasis (Fig. 2M), brain metastasis (Fig. 2N), and surgical treatments of the primary site (Fig. 2O) are shown in Fig. 2.
Table 2
Cox regression for analyzing the mortality among lung metastasis patients in colorectal cancer (diagnosed 2010–2015)
Subject characteristics
No. of CRC patients with LM (N = 8867)
Survival, median (95% CI, month)
Univariable analysis
Multivariable analysisa
Overall
Deceased (rate, %)
HR [95% CI]
P value
HR [95% CI]
P-value
Age(years)
       
 ≤ 50
1313
1007 (76.7)
18 (16.7–19.3)
1 (Reference)
1.00
1 (Reference)
1.00
51–60
2115
1698 (80.3)
14 (13.0–15.0)
1.18 (1.09–1.27)
 < 0.001
1.14 (1.05–1.23)
0.001
61–70
2353
1937 (82.3)
11 (10.2–11.9)
1.32 (1.22–1.42)
 < 0.001
1.31 (1.21–1.41)
 < 0.001
71–80
1745
1549 (88.8)
6 (5.3–6.8)
1.76 (1.62–1.90)
 < 0.001
1.82 (1.68–1.98)
 < 0.001
81–90
1121
1062 (94.7)
2 (1.7–2.3)
2.69 (2.46–2.93)
 < 0.001
2.72 (2.48–2.98)
 < 0.001
 ≥ 91
220
216 (98.2)
1 (0.4–1.6)
3.89 (3.36–4.51)
 < 0.001
3.61 (3.09–4.21)
 < 0.001
Sex
       
Female
4068
3416 (84.0)
9 (8.3–9.7)
1 (Reference)
1.00
-
-
Male
4799
4053 (84.5)
10 (9.4–10.6)
0.99 (0.95–1.04)
0.787
-
-
Race
       
White
6525
5475 (83.9)
10 (9.5–10.6)
1 (Reference)
1.00
1 (Reference)
1.00
Black
1424
1233 (86.6)
9 (8.0–10.0)
1.08 (1.01–1.15)
0.016
1.06 (1.00–1.13)
0.060
Othersb
902
750 (83.2)
10 (8.6–11.4)
0.98 (0.90–1.05)
0.542
1.02 (0.94–1.10)
0.690
Unknown
16
11 (68.8)
12 (2.7–21.3)
0.96 (0.53–1.73)
0.885
1.14 (0.63–2.07)
0.663
Marital status
       
Unmarriedc
4315
3739 (86.7)
8 (7.4–8.6)
1 (Reference)
1.00
1 (Reference)
1.00
Married
4060
3320 (81.8)
13 (12.3–13.7)
0.79 (0.75–0.82)
 < 0.001
0.87 (0.83–0.91)
 < 0.001
Unknown
492
410 (83.3)
8 (6.0–10.0)
0.87 (0.78–0.96)
0.005
0.92 (0.83–1.02)
0.119
Insurance status
       
Insured
6763
5665 (83.8)
10 (9.5–10.5)
1 (Reference)
1.00
1 (Reference)
1.00
Uninsured
1598
1376 (86.1)
9 (8.1–9.9)
1.10 (1.00–1.21)
0.058
1.24 (1.16–1.32)
 < 0.001
Any Medic aid
506
428 (84.6)
9 (7.1–10.9)
1.11 (1.05–1.18)
0.001
1.35 (1.22–1.49)
 < 0.001
Site
       
Right colon
2617
2309 (88.2)
7 (6.3–7.7)
1 (Reference)
1.00
1 (Reference)
1.00
Left colon
2986
2435 (81.6)
12 (11.1–12.9)
0.76 (0.72–0.81)
 < 0.001
0.82 (0.77–0.87)
 < 0.001
Rectum
2399
1922 (80.1)
14 (13.1–15.0)
0.69 (0.64–0.73)
 < 0.001
0.68 (0.64–0.73)
 < 0.001
Unknown
865
803 (92.8)
2 (1.5–2.5)
1.51 (1.39–1.63)
 < 0.001
1.11 (1.02–1.21)
0.018
Histological grade
       
Grade I
356
280 (78.7)
14 (11.1–16.9)
1 (Reference)
1.00
1 (Reference)
1.00
Grade II
4050
3202 (79.1)
15 (14.2–15.8)
0.99 (0.87–1.11)
0.810
1.08 (0.95–1.22)
0.244
Grade III
1167
1031 (88.4)
7 (6.1–7.9)
1.49 (1.31–1.71)
 < 0.001
1.58 (1.38–1.81)
 < 0.001
Grade IV
195
166 (85.1)
8 (5.6–10.4)
1.34 (1.11–1.63)
0.003
1.51 (1.24–1.83)
 < 0.001
Unknown
3099
2790 (90.0)
5 (4.5–5.5)
1.78 (1.57–2.01)
 < 0.001
1.32 (1.16–1.49)
 < 0.001
Lymphatic metastasis
       
N0
3021
2542 (84.1)
8 (7.2–8.8)
1 (Reference)
1.00
1 (Reference)
1.00
N1
2938
2388 (81.3)
12 (11.1–12.9)
0.85 (0.81–0.90)
 < 0.001
1.02 (0.96–1.08)
0.485
N2
1315
1078 (82.0)
14 (12.7–15.3)
0.79 (0.74–0.85)
 < 0.001
1.17 (1.07–1.27)
 < 0.001
Unknown
1593
1461 (91.7)
8 (7.2–8.8)
1.37 (1.28–1.46)
 < 0.001
1.07 (1.00–1.14)
0.068
T stage
       
T1
1052
920 (87.5)
8 (6.7–9.3)
1 (Reference)
1.00
1 (Reference)
1.00
T2
151
114 (75.5)
19 (14.2–23.8)
0.48 (0.37–0.63)
 < 0.001
0.78 (0.60–1.02)
0.071
T3
2285
1717 (75.1)
19 (17.9–20.1)
0.75 (0.69–0.82)
 < 0.001
0.93 (0.85–1.02)
0.118
T4
1875
1572 (83.8)
11 (10.1–11.9)
0.83 (0.75–0.92)
 < 0.001
1.07 (0.96–1.18)
0.223
Unknown
3504
3146 (89.8)
5 (4.5–5.5)
1.23 (1.13–1.35)
 < 0.001
1.01 (0.92–1.11)
0.792
CEA
       
Negative
745
543 (72.9)
20 (17.7–22.3)
1 (Reference)
1.00
1 (Reference)
1.00
Positive
5282
4477 (84.8)
10 (9.5–10.6)
1.62 (1.48–1.77)
 < 0.001
1.27 (1.16–1.39)
 < 0.001
Unknown
2840
2449 (86.2)
8 (7.2–8.8)
1.73 (1.57–1.89)
 < 0.001
1.34 (1.21–1.47)
 < 0.001
Liver metastasis
       
No
2406
1759 (73.1)
17 (15.8–18.2)
1 (Reference)
1.00
1 (Reference)
1.00
Yes
6350
5612 (88.4)
8 (7.5–8.5)
1.75 (1.66–1.85)
 < 0.001
1.64 (1.55–1.73)
 < 0.001
Unknown
111
98 (88.3)
8 (3.5–12.5)
1.52 (1.24–1.86)
 < 0.001
1.21 (0.97–1.50)
0.098
Bone metastasis
       
No
7663
6357 (83.0)
11 (10.5–11.5)
1 (Reference)
1.00
1 (Reference)
1.00
Yes
899
829 (92.2)
5 (4.2–5.8)
1.55 (1.45–1.67)
 < 0.001
1.38 (1.28–1.48)
 < 0.001
Unknown
305
283 (92.8)
4 (2.6–5.4)
1.47 (1.30–1.65)
 < 0.001
1.32 (1.09–1.60)
0.004
Brain metastasis
       
No
8267
6921 (83.7)
10 (9.5–10.5)
1 (Reference)
1.00
1 (Reference)
1.00
Yes
248
227 (91.5)
3 (2.0–4.0)
1.68 (1.47–1.92)
 < 0.001
1.51 (1.32–1.73)
 < 0.001
Unknown
352
321 (91.2)
5 (3.8–6.3)
1.36 (1.22–1.52)
 < 0.001
0.86 (0.72–1.03)
0.103
Surg (pri)
       
No
5956
5286 (88.8)
7 (6.6–7.4)
1 (Reference)
1.00
1 (Reference)
1.00
Yes
2878
2157 (75.0)
19 (17.9–20.1)
0.51 (0.49–0.54)
 < 0.001
0.56 (0.52–0.60)
 < 0.001
Unknown
33
26 (78.8)
12 (3.5–20.5)
0.59 (0.40–0.87)
0.007
0.45 (0.31–0.67)
 < 0.001
CEA, carcinoembryonic antigen; CRC, colorectal cancer; CI, confidence interval; HR, hazard ratio; LM, lung metastasis; NA, not available; Surg(pri), surgical treatments of primary site
aAdjusted for age, race, marital status, insurance status, site, histological grade, lymphatic metastasis, T stage, CEA, liver metastasis, bone metastasis, and brain metastasis
bIncludes American Indian/Alaska Native and Asian or Pacific Islander
cIncludes single, separated, widowed, and divorced
The univariate analysis suggested that older age, unmarried status, insurance status, right colon, poor histological differentiation, N stage, T stage, CEA positivity, liver metastasis, bone metastasis, brain metastasis and no surgical treatments of the primary tumour were associated with poor prognosis. Multivariable Cox regression confirmed that older age, unmarried status, uninsured status, right colon, poor histological differentiation, more lymphatic metastasis, positive CEA, liver metastasis, bone metastasis, brain metastasis and no surgical treatments of the primary tumour were all risk factors for poorer prognosis. See Table 2 for more details.

Homogeneous and heterogeneous risk and prognostic factors

According to the results of multivariable logistic regression and multivariable Cox regression analyses, the homogeneous lung metastasis risk and prognostic factors in CRC were older age, unmarried status, uninsured status, poor histological differentiation, more lymphatic metastasis, CEA positivity, liver metastasis, bone metastasis, and brain metastasis. However, patients with black race, left colon, rectum, and T4 stage disease were more likely to develop lung metastasis, while patients with right colon disease without surgical treatment of primary tumours had poor survival outcomes (Fig. 3).

Discussion

We investigated the incidence of synchronous lung metastasis in newly diagnosed CRC patients using SEER database information. Synchronous lung metastasis occurred in 5.2% of CRC patients. This incidence was lower than those reported in Mitry’s study (11.3%) [5] and Yahagi’s study (6.9%) [10] but higher than those reported in Huang’s study (2.4%) [6]. This is presumably due to the different sample sizes of the study population. In addition, the SEER database only records confirmed patients who have been comprehensively evaluated, and some asymptomatic patients may be missed. Therefore, the incidence in this study may be underestimated.
Accurately identifying the population at high risk for lung metastasis is helpful for subsequent individualized treatment. Our results showed that patients with older age, black race, left colon, rectum, poorly differentiated grade, more lymphatic metastasis, T4 stage, CEA positivity and liver metastasis, bone metastasis and brain metastasis were more likely to develop lung metastasis. Given that stage T1 and stage T2 CRC patients have much lower risk of metastasis, another univariate and multivariate logistic regression analyses were performed which only included patients with stage T3 and stage T4 CRC (see Additional file 1: Table S1). We found the results were comparable when the sample was restricted to stages T3 and stage T4 patients. This also suggests that it is necessary to screen lung metastasis in CRC patients with higher T stage. In addition, unmarried and uninsured patients were also at high risk for lung metastasis. Nevertheless, previous studies did not investigate the impact of marital status and insurance status on the incidence of lung metastasis [5, 6]. A 30-year population-based study found that only the primary site of CRC was significantly associated with synchronous lung metastasis [5]. The results of another study are similar to ours, except for marital status and insurance status [6]. Therefore, the relationship between marital status, insurance status, and lung metastasis incidence warrants further investigation. Regardless, patients with the above risk factors are recommended for lung metastasis screening.
In addition to risk factors, identifying prognostic factors is important in cancer management. We found 11 prognostic factors, including older age, unmarried status, insurance status, right colon, poor histological differentiation, more lymphatic metastasis, CEA positivity, liver metastasis, bone metastasis, brain metastasis and no surgery. Surprisingly, there was no significant correlation between T stage and prognosis of lung metastasis patients, which was consistent with the findings of Huang’s study [6]. Notably, the survival time in patients with stage T1 disease was lower than that in patients with stage T2 to T4 disease. In addition, T stage was found to be a prognostic factor in the univariate Cox regression, while it became a nonsignificant factor in the multivariate Cox regression. T stage has also been found not to be a prognostic factor in patients with brain metastasis [11]. Therefore, we conclude that T stage cannot be used to estimate survival in CRC patients. However, T stage has been reported as an independent prognostic factor in CRC patients with liver metastasis or bone metastasis [9, 12]. Accordingly, the relationship between T stage and the prognosis of distant metastases in CRC patients is still controversial and requires further investigation.
Based on the analysis of risk and prognostic factors, the most important findings in this research were the nine homogeneous factors. To the best of our knowledge, this is the first report to describe the homogeneous factors associated with lung metastasis in CRC patients. These factors can be used to predict the occurrence of lung metastasis, estimate the prognosis, and improve lung metastasis screening for CRC patients. Among the nine homogeneous factors, different metastatic organs ranked much higher in both odds ratio and hazard ratio. Liver metastasis ranked highest, followed by bone metastasis and brain metastasis, indicating that lung metastasis was closely related to liver metastasis. One previous study found that the expression of several key genes plays an important role in determining the distant metastasis of CRC to these two organs [13, 14]. However, the specific molecular mechanisms by which CRC cells affect the liver and lung remain unclear and need to be further studied [15]. Nonetheless, our results suggest that routine liver scanning is necessary for patients with lung metastatic CRC.
In terms of heterogeneous factors, we found that patients with tumours located in the left colon and rectum were more likely to develop lung metastasis, which was consistent with the results of Qiu’s study [3]. The results of this study also showed that patients with lung metastasis from right colon cancer had worse survival than those with metastasis from left colon cancer. This finding is also consistent with the results of previous studies [1618]. In addition to the primary site, surgical treatment is another heterogeneous factor. Patients who underwent surgical resection of the primary tumour survived longer than those who did not [19]. Some studies have shown that resection of lung metastasis also has a positive effect on improving survival outcomes [2023]. Therefore, surgical resection of both the primary tumour and the metastasis is an effective measure for CRC patients with lung metastasis.
This study has some limitations. Only patients with synchronous lung metastasis were studied, and the incidence and prognosis of patients with metachronous lung metastasis are still unclear. Meanwhile, the incidence of lung metastasis may be underestimated. In addition, since other important information, including chemotherapy and radiotherapy, was not available from the SEER database, their impact on survival in CRC patients still needs to be further studied. Despite these limitations, our study based on a large cohort of CRC patients demonstrated homogeneous and heterogeneous risk and prognostic factors for lung metastasis. These findings may be helpful for clinicians to identify high-risk patients and improve lung metastasis screening for CRC patients.

Conclusion

In this study, we found that the incidence of lung metastasis in CRC patients was 5.2%, and the median survival of CRC patients with lung metastasis was 10.0 months. Some lung metastasis risk and prognostic factors were found. A total of nine homogeneous risk factors and several heterogeneous factors were identified. These results are helpful for clinicians to conduct clinical evaluations and individualize treatment strategies.

Acknowledgements

The authors acknowledge the National Cancer Institute for providing the SEER dataset.

Declarations

As the data used was from SEER which is an open public database, the present study was exempt from the ethical review of the ethics board of the First Affiliated Hospital of Chongqing Medical University. The present study complied with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
Not applicable.

Competing interests

The authors declare that they have no conflicts of interest.
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Metadaten
Titel
Homogeneous and heterogeneous risk and prognostic factors for lung metastasis in colorectal cancer patients
verfasst von
Hongmei Wang
Xuefeng Shan
Min Zhang
Kun Qian
Zhengze Shen
Weiying Zhou
Publikationsdatum
01.12.2022
Verlag
BioMed Central
Erschienen in
BMC Gastroenterology / Ausgabe 1/2022
Elektronische ISSN: 1471-230X
DOI
https://doi.org/10.1186/s12876-022-02270-5

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