Table 1

Clinical characteristics of the study population and of DNA methylation-based tumour clusters

TotalCluster 1Cluster 2
Subjects, n (%)4627 (58.7)19 (41.3)
Demographics
 Age, years, mean (SD)67.0 (8.0)66.1 (8.4)68.3 (7.4)
 Male sex, n (%)39 (84.8)23 (85.2)16 (84.2)
Smoking behaviour
 Pack-years history, mean (SD)44.3 (23.4)44.4 (27.0)44.1 (17.8)
 Smoked years, mean (SD)43.0 (12.7)40.4 (13.2)46.8 (11.2)
 Current smokers, n (%)29 (63.0)16 (59.3)13 (68.4)
COPD, n (%)27 (58.7)12 (44.4)15 (78.9)
COPD GOLD stage, n (%)
 Stage I11 (23.9)4 (33.3)7 (46.7)
 Stage II15 (32.6)8 (66.7)7 (46.7)
 Stage III0 (0.0)0 (0.0)0 (0.0)
 Stage IV1 (2.2)0 (0.0)1 (6.7)
Histological type, n (%)
 Adenocarcinoma25 (54.3)16 (59.3)9 (47.4)
 Squamous cell21 (45.7)11 (40.7)10 (52.6)
Tumour stage, n (%)
 IA11 (23.9)4 (14.8)7 (36.8)
 IB9 (19.6)5 (18.5)4 (21.1)
 IIA9 (19.6)6 (22.2)3 (15.8)
 IIB6 (13.0)5 (18.5)1 (5.3)
 IIIA9 (19.6)6 (22.2)3 (15.8)
 IV2 (4.3)1 (3.7)1 (5.3)
COPD treatment, n (%)16 (34.8)9 (33.3)7 (36.8)
 LAMA7 (15.2)5 (18.5)2 (10.5)
 LABA1 (2.2)1 (3.7)0 (0.0)
 ICS14 (30.4)8 (29.6)6 (31.6)
 CS4 (8.7)3 (11.1)1 (5.3)
Emphysema, n (%)
 None10 (21.7)5 (18.5)5 (26.3)
 Mild27 (58.7)17 (63)10 (52.6)
 Moderate8 (17.4)5 (18.5)3 (15.8)
 Severe1 (2.2)0 (0.0)1 (5.3)
  • Categorical variables are expressed as number (n) and percentage (%). Percentages represent column percentages. Continuous variables are expressed as mean and SD.

  • Clusters were determined by RPMM-based clustering of normalised tumour β values.

  • CS, oral corticosteroids; GOLD, Global Initiative for Chronic Obstructive Lung Disease; ICS, inhaled corticosteroid; LABA, inhaled long-acting β2-agonists; LAMA, long-acting muscarinic antagonists; RPMM, recursively partitioned mixture model.