Figures
- Figure 1–
Flow diagram showing the criteria for group assignment and reasons for individuals to be excluded. a) Healthy volunteers tested to be included into group A. b) Patients suspected of having lung cancer on the basis of patient history and pathological imaging to be included into group B after confirmation of the diagnosis by histology. c) Patients treated for chronic obstructive pulmonary disease (COPD) to be included into group C. The flow chart indicates that breath samples were obtained at the beginning of each individual patient evaluation process and were assigned to the respective study groups thereafter. CT: computed tomography.
- Figure 2–
Applied methods for breath sampling and testing. a) Glass tube used for breath sampling. The lumen is filled with the polypropylene fleece. b) For breath sampling, study participants exhaled five times through the collection device. c) Test set-up showing the probe retainers. d) The position of the lung cancer samples was randomised. e) Sniffer dogs were trained to identify lung cancer in the breath sample of patients. f) The dogs were trained to indicate a positive test tube by lying on the floor in front of the tube with the muzzle touching the test tube.
- Figure 3–
Itemisation of trained and tested tumour stages. a) Early and advanced lung cancer tumour stages were trained and tested. b) Distribution of tested tumour histologies. SCC: squamous cell carcinoma; SCLC: small cell lung cancer.
Tables
- Table 1– Breath sample distribution throughout the study
Group A
healthyGroup B
lung cancerGroup C
COPDTraining 60 35 Test I 40 10 Test II 10 40 Test III 10 5 10 Total 110 60 50 Data are presented as n. COPD: chronic obstructive pulmonary disease.
- Table 2– Composition of training and test groups
Group A: healthy Group B: lung cancer Group C: COPD All Training Test p-value# All Training Test p-value# Test p-value¶ Subjects 110 60 50 60 35 25 50 Age yrs 46.2±14.0 45.7±12.5 46.8±15.8 ns 63.6±10.3 65.3±9.8 62.6±11.1 ns 66.7±6.6 <0.001 Sex M/F 26/74 28/72 24/76 78/22 71/29 88/12 56/44 BMI kg·m−2 25.3±5.3 25.2±5.4 25.4±5.1 25.4±4.4 24.9±4.7 26.1±4.0 26.5±5.2 ns Current smoker 14 (12.7) 9 (15) 5 (10.0) 13 (21.7) 7 (20.0) 6 (24.0) 13 (26.0) History of cancer 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 3 (5) Previous surgery 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 1 (1.7) Previous intervention 0 (0) 0 (0) 0 (0) 34 (57) 18 (51) 16 (64) 0 (0) <0.001 Sample age days 23.6±19.0 22.3±21.1 25.2±16.1 38.5±22.4 39.4±22.5 37.3±22.8 8.1±3.8 ns Data are presented as n, mean±sd, %/% or n (%), unless otherwise stated. COPD: chronic obstructive pulmonary disease; M: male; F: female; BMI: body mass index; ns: nonsignificant. #: training versus test; ¶: for comparison of test groups A, B and C.
- Table 3– Lung function tests in training and test groups
Group A: healthy Group B: lung cancer Group C: COPD All Training Test p-value# All Training Test p-value# Test p-value¶ Subjects 110 60 50 60 35 25 50 VC L 4.0±1.0 4.1±1.0 3.8±0.8 ns 3.5±1.1 2.9±1.1 3.5±1.1 ns 2.8±0.8 <0.001 VC % 107±14 111±12 103±16 <0.01 83±21 79±22 83±21 79±20 FEV1 L 3.3±0.8 3.4±0.8 3.2±0.8 ns 2.4±0.8 2.1±1.0 2.4±0.8 1.6±0.6 FEV1 % 109±15 112±13 105±17 <0.05 74±25 73±25 76±25 61±19 FEV1 %VC 81.2±5.9 80.6±5.9 82.0±5.9 ns 65±13 65±13 66±12 59±11 TLC L 6.0±1.3 5.9±1.3 6.0±1.3 5.8±1.3 5.9±1.3 5.8±1.3 7.1±1.4 TLC % 105±18 104±13 107±22 92±20 97±21 85±16 120±20 RV L 1.8±1.1 1.6±0.8 2.1±1.3 2.5±1.2 2.7±1.4 2.1±0.7 4.4±1.2 RV % 97±52 87±30 109±69 106±49 118±58 88±25 187±56 GOLD 0±0.2 0±0.2 0±0.3 1.1±1.3 1.2±1.4 1.1±1.3 1.9±1.0 Data are presented as n or mean±sd, unless otherwise stated. COPD: chronic obstructive pulmonary disease; VC: vital capacity; FEV1: forced expiratory volume in 1 s; TLC: total lung capacity; RV: residual lung volume; GOLD: stage of COPD according to the Global Initiative for Chronic Obstructive Lung Disease; ns: nonsignificant. #: training versus test; ¶: for comparison of test groups A, B and C.
- Table 4– Cross-tabulation of the dogs’ indication and the presence of cancer
Breath sample of volunteer without cancer (groups A+C) Breath sample of volunteer with confirmed lung cancer (group B) Total Dogs indicating presence of lung cancer 28 71 99 Dogs indicating absence of lung cancer 372 29 401 Total 400 100 500 Data are cumulative results and are presented as n.
- Table 5– Hit ratio of sniffer dogs
Dog 1 Dog 2 Dog 3 Dog 4 Corporate decision# Test I Correct 7 4 6 5 False 3 6 4 5 Test II Correct 9 8 7 8 False 1 2 3 2 Test III Correct 5 5 4 5 False 0 0 1 0 Overall Correct 21 17 17 18 False 4 8 8 7 Percentage correct 84 68 68 72 Inter-ratervariability κ 0.436 Sensitivity 0.72 (0.51–0.88) Specificity 0.94 (0.87–0.98) PPV 0.75 (0.53–0.91) NPV 0.93 (0.86–0.97) Data are presented as n or value (95% confidence interval), unless otherwise stated. PPV: positive predictive value; NPV: negative predictive value. #: at least three dogs alike.
Supplementary material
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Table 6
Table 7
Figure 4
- Supplementary material -
Supplementary material
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Press release
Files in this Data Supplement:
- Press release - Sniffer dogs could be used for the early detection of lung cancer, according to new research published in the European Respiratory Journal.
