Specific gut microbiome signature predicts the early-stage lung cancer

Figures & data

Table 1. Baseline characteristics of the discovery cohort.

	Patients with lung cancer (n = 42)	Healthy control (n = 65)	P value*
Demographics/anthropometric
Age yr (mean ± SD)	57.48 ± 12.49	58.60 ± 4.86	0.51
Male/female (No.)	18/24	10/55	0.003
BMI (kg/m^2) (mean ± SD)	23.73 ± 2.87	23.37 ± 2.45	0.49
Tumor stage (%)
0	6 (14.29%)	N/A
I	32 (76.19%)	N/A
II	4 (9.52%)
Tumor type (%)
ADC	37 (88.10%)	N/A
SCC	3 (7.14%)
LCC	2 (4.76%)
Tumor metastasis (%)		N/A
Metastasis	3 (7.14%)
Non-metastasis	39 (92.86%)
Smoking status (%)
Never smoker	41 (97.62%) N/I
Ever smoker	1 (2.38%)

Unpaired t-test was used to compare age and BMI between lung cancer group and healthy controls; Fisher’s exact test was used to compare gender distribution between the two groups. N/A, not applicable; N/I, no information.

Figure 1. Gut microbiota dysbiosis in lung cancer patients. (a) Numbers of OTUs observed in patients and healthy controls. (b) Microbial richness based on the Chao index and diversity based on the Shannon index. The box represented the interquartile range (IQR) between the first and the third quartiles, and the midline represented the median. Whiskers extended to values within 1.5 times IQR. Circles indicated outliers beyond the whiskers. (c) Principal coordinates analysis (PCoA) for lung cancer (orange) and healthy control samples (green). Left, Unweighted UniFrac; right, Bray–Curtis. Significant differences were observed between patients and healthy controls with ANOSIM test (UniFrac, R = 0.0912, P = .003; Bray–Curtis, R = 0.0739, P = .007). The first two principal coordinates (PCs) were each labeled with the percentage of variance explained.

Figure 2. Differential abundance of gut microbiota in lung cancer and healthy controls. The taxa decreased (a) and increased (b) in patients with lung cancer at the phylum, genus, and species levels, p < .05. Green and orange represented the healthy controls (n = 65) and lung cancer patients (n = 42), respectively. The distributions of taxa were based on the number of reads post-filtering and rarefying. The abundance in each group was plotted as log₁₀ scale on the y axis. P values were calculated using the two-tailed Wilcoxon rank-sum test. Description of boxplots was the same as in Figure 1. Taxa were named as their lowest possible level of classification, with unclassified (unc) indicating no further classification available.

Figure 3. Association between clinical variables and gut microbiota abundance. Heat map showing the relative abundances of the 50 most abundant species in samples grouped by metastatic status (a) and lung cancer subtypes (c), respectively. Species were in rows, and the relative abundance was indicated by color gradient. The most significantly changed species were further analyzed in each group (b, d). Description of boxplots was the same as in Figure 1. Two-tailed Wilcoxon rank-sum test, *p < .05, **p < .01, ***p < .001.

Table 2. Thirteen OTU-based markers.

No.	OTU ID and species level name
1	OTU818: Bacteroides_unc. versus OTU939: Bacteroides_f__Bacteroidaceae ovatus
2	OTU163: Bacteroides_unc. versus OTU939: Bacteroides_f__Bacteroidaceae ovatus
3	OTU786: Streptococcus infantis versus OTU312: Blautia_unc
4	OTU358: Erysipelotrichaceae_unc versus OTU1063: Blautia_unc
5	OTU236: Clostridiales_unc versus OTU1100: Lachnospiraceae_unc
6	OTU1283: Roseburia faecis versus OTU1063: Blautia_unc
7	OTU888: Bacteria_unc versus OTU939: Bacteroides_f__Bacteroidaceae ovatus
8	OTU163: Bacteroides_unc versus OTU1002: Bacteroides_unc
9	OTU1222: Clostridium_unc versus OTU1002: Bacteroides_unc
10	OTU1285: Ruminococcus bromii versus OTU1100: Lachnospiraceae_unc
11	OTU890: Enterobacteriaceae_unc versus OTU312: Blautia_unc
12	OTU1353: Veillonella dispar versus OTU1100: Lachnospiraceae_unc
13	OTU1222: Clostridium_unc versus OTU312 Blautia_unc

These markers were each formatted as “OTU1: species1 versus OTU2: species2,” where OTU1 belonged to species 1 and the reference OTU2 belonged to species2.

Figure 4. OTU-based diagnostic biomarkers for lung cancer. (a, b) Receiver operating characteristic (ROC) curves of prediction efficacy for the OTU-based predictors using SVM (a) and PDI (b), respectively. Solid and dashed lines indicated the discovery (patient = 42, healthy = 65) and validation (patient = 34, healthy = 40) cohorts, respectively. (c) PDI distributions in early-stage patients and healthy controls. Two-tailed Wilcoxon rank-sum test, **p < .01.