Survival prediction for non-small cell lung cancer patients treated with CT-guided microwave ablation: development of a prognostic nomogram

Figures & data

Figure 1. Patient selection flowchart. PLC: primary lung cancer; MWA: microwave ablation; NSCLC: non-small cell lung cancer; SCLC: small cell lung cancer.

Table 1. Clinical characteristics of NSCLC patients treated with MWA.

Variables	Overall (n = 234)	Training cohort (n = 176)	Validation cohort (n = 58)	p-Value
Age (y)				0.482
<70	136 (58.1%)	100 (56.8%)	36 (62.1%)
≥70	98 (41.9%)	76 (43.2%)	22 (37.9%)
Gender				0.526
Male	141 (60.3%)	104 (59.1%)	37 (63.8%)
Female	93 (39.7%)	72 (40.9%)	21 (36.2%)
Underlying pulmonary diseases	17 (7.3%)	14 (8.0%)	3 (5.2%)	0.182
COPD	5 (2.1%)	4 (2.4%)	1 (1.7%)
Pulmonary fibrosis	3 (1.3%)	3 (1.7%)	0
Chronic bronchitis	3 (1.3%)	2 (1.1%)	1 (1.7%)
Tuberculosis	5 (2.1%)	5 (2.8%)	0
Others	1 (0.4%)	0	1 (1.7%)
Tumor type				0.505
Adenocarcinoma	164 (70.1%)	120 (68.2%)	44 (75.9%)
Squamous cell carcinoma	58 (24.8%)	46 (26.1%)	12 (20.7%)
Others	12 (5.1%)	10 (5.7%)	2 (3.4%)
Tumor stage				0.411
I	43 (18.4%)	35 (19.9%)	8 (13.8%)
II	27 (11.5%)	19 (10.8%)	8 (13.8%)
III	61 (26.1%)	42 (23.9%)	19 (32.8%)
IV	103 (44.0%)	80 (45.5%）	23 (39.7%)
CEA (ng/ml)				0.822
<5	120 (51.3%)	91 (51.7%)	29 (50%)
≥5	114 (48.7%)	85 (48.3%)	29 (50%)
Treatment history
Previous ipsilateral surgery	33 (14.1%)	26 (14.8%)	7 (12.1%)	0.608
Previous chemotherapy	41 (17.5%)	36 (20.5%)	5 (8.6%)	0.063
Previous radiotherapy	16 (6.8%)	11 (6.3%)	5 (8.6%)	0.749
Previous TKIs	43 (18.4%)	35 (19.9%)	8 (13.8%)	0.299
Radiological features
Number of metastases				0.969
<2	186 (79.5%)	140 (79.5%)	46 (79.3%)
≥2	48 (20.5%)	36 (20.5%)	12 (20.7%)
Tumor diameter (cm)				0.996
<3	109 (46.6%)	82 (46.6%)	27 (46.6%)
≥3	125 (53.4%)	94 (53.4%)	31 (53.4%)
Tumor numbers				0.343
1	201 (85.9%)	149 (84.7%)	52 (89.7%)
≥2	33 (14.1%)	27 (15.3%)	6 (10.3%)
Extrapulmonary metastases	69 (29.5%)	54 (30.7%)	15 (25.9%)	0.485
Emphysema	67 (28.6%)	57 (32.4%)	10 (17.2%)	0.027
Post-MWA treatments
Post-MWA chemotherapy	54 (23.1%)	40 (22.7%)	14 (24.1%)	0.825
Post-MWA radiotherapy	33 (14.1%)	29 (16.5%)	4 (6.9%)	0.118
Post-MWA TKIs	98 (41.9%)	64 (36.4%)	34 (58.6%)	0.003
Post-MWA immunotherapy	24 (10.3%)	17 (9.7%)	7 (12.1%)	0.600
Mortality	132 (56.4%)	98 (55.7%)	34 (58.6%)	0.695
Median OS (months)	17.0 ± 12.2	18.0 ± 12.2	13.0 ± 12.0	0.087
Median PFS (months)	12.5 ± 12.2	14.0 ± 12.1	10.0 ± 12.2	0.148
Follow-up (months)	30.5 ± 11.2	31.6 ± 10.9	27.1 ± 11.5	0.008

Note. Frequencies and percentages are reported for categorical variables and mean/median ± SD are reported for continuous variables. NSCLC: non-small cell lung cancer; MWA: microwave ablation; COPD: chronic obstructive pulmonary diseases; CEA: carcinoembryonic antigen; TKI: tyrosine kinase inhibitor: OS: overall survival.

Table 2. The detailed kinds of TKIs for NSCLC patients treated with MWA.

Variables	Previous TKIs (n = 43)	Post-MWA TKIs (n = 98)
Gefitinib	23 (9.8%)	42 (17.9%)
Icotinib	17 (7.3%)	33 (14.1%)
Arotinib	4 (1.7%)	20 (8.5%)
Oxitinib	8 (3.4%)	16 (6.8%)
Afatinib	2 (0.9%)	4 (1.7%)
Aletinib	1 (0.4%)	3 (12.8%)
Crizotinib	2 (0.9%)	6 (2.6%)
Lorlatinib	0	2 (0.9%)

TKI: tyrosine kinase inhibitor; NSCLC: non-small cell lung cancer; MWA: microwave ablation.

Table 3. Complications of NSCLC patients treated with MWA.

Complications	Patients	Percentage of procedures (%)
Side effects	18	7.7
Pneumothorax	12	5.1
Pleural effusion	6	2.6
Intraprocedural minor complications	34	14.5
Pneumothorax	26	11.1
Pleural effusion	10	4.3
Intraprocedural major complications	1	0.4
Hemorrhage	1	0.4
Diaphragmatic and neural injury	0	0
Air embolism	0	0
Delayed major complications	3	1.2
Pleuritis	0	0
Pneumonia	2	0.9
Lung abscess formation	0	0
Bronchopleural fistula	1	0.4
Mortality	0	0

NSCLC: non-small cell lung cancer; MWA: microwave ablation.

Figure 2. Forrest plot of the OS (with 95%confidence intervals) of NSCLC patients treated with MWA.

Figure 3. Kaplan–Meier analyses of OS. (a) The median OS were 41.0 months for patients with adenocarcinoma, 12.0 months for patients with squamous cell carcinoma, and 8.0 months for patients with other types. (b) The median OS were 39.0 months for patients with Stage I, 24.0 months for patients with Stage II, 21.0 months for patients with Stage III and 15.0 months for patients with Stage IV. (c). The median OS was 35.0 months for patients with <3 cm in diameter compared with 16.0 months for patients with ≥3cm in diameter. (d) The median OS was 36.0 months for patients with post-MWA TKIs compared with 17.0 months than those patients without. (e) The median OS was 13.0 months for patients with extrapulmonary metastases compared with 36.0 months than those patients without.

Table 4. Univariate analyses for OS of NSCLC patients treated with MWA in the training cohort.

Variables	Univariate analyses
	Median OS (95%CI)	p-Value*
Gender		0.002
Male	18.0 (14.9–21.1)
Female	38.0 (27.9–36.7)
Tumor type		<0.001
Adenocarcinoma	41.0 (29.1–35.7)
Squamous cell carcinoma	12.0 (7.6–16.4)
Others	8.0 (3.4–12.6)
Tumor stage		<0.001
I	39.0 (35.4–45.0)
II	24.0 (17.0–31.0)
III	21.0 (14.5–27.6)
IV	15.0 (11.6–18.4)
Tumor diameter(cm)		<0.001
<3	35.0 (30.4–38.3)
≥3	16.0 (12.7–19.3)
Tumor numbers		0.013
1	25.0 (14.7–35.3)
≥2	16.0 (13.6–18.4)
Extrapulmonary metastases		<0.001
Yes	13.0 (8.5–17.5)
No	36.0 (24.7–47.4)
Post-MWA TKIs		0.004
Yes	36.0 (20.3–51.7)
No	17.0 (12.1–21.9)

Note. *Log-rank test was used. The potential predictors that showed correlation with OS in the univariate analyses were presented in this table. OS: overall survival; NSCLC: non-small cell lung cancer; MWA: microwave ablation; CI: confidence interval; TKI: tyrosine kinase inhibitor.

Figure 4. (a). Prognostic nomogram for predicting OS in NSCLC patients treated with MWA. To use the nomogram, an individual patient’s value is located on each variable axis, and a line is drawn upward to determine the number of points received for each variable value. The sum of these numbers is located on the Total Point axis, and a line is drawn downward to the risk axes to determine the likelihood of median OS. The linear predictor represented the product of the independent variable and correlation coefficient. (b) OS of low-risk and high-risk group in the entire cohort.

Figure 5. Receiver operating characteristic curve analyses for the nomograms in internal and external validation. The diagonal red line indicates that the index of AUC was 0.5, which was a reference value. C-statistic was calculated as the area between the ROC curve (blue curve) and horizontal axis. (a) The area under the curve (C-statistic) was 0.838 (95% CI, 0.779-0.897) in the training cohort for predicting OS. (b) The area under the curve (C-statistic) was 0.808 (95% CI, 0.695–0.920) in the validation cohort for predicting OS.

Figure 6. (a) Calibration curve for predicting 3-year survival after MWA in the training cohort. (b) Calibration curve for predicting 3-year survival after MWA in the validation cohort. The diagonal dotted line is a reference value while the solid line is curve fitting line.