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Table 1 Characteristics of lung cancer cases and controls by quintiles of cg05575921 percent methylation

From: AHRR methylation in heavy smokers: associations with smoking, lung cancer risk, and lung cancer mortality

  All Q1 Q2 Q3 Q4 Q5  
(hyper-methylated) (hypo-methylated)
Quintile range 34–98 84–98 73–84 64–73 56–64 34–56
Lung cancer casesa
  (n = 316) (n = 59) (n = 78) (n = 59) (n = 49) (n = 71) P-trendb
cg05575921, % methylation; mean (SD) 69.1 (14.6) 89.6 (3.8) 78.0 (3.1) 68.2 (2.7) 60.0 (2.4) 49.2 (5.0)
Age at blood draw, years; mean (SD) 64.5 (5.5) 65.9 (5.8) 65.5 (5.5) 64.9 (5.7) 63.8 (4.9) 62.5 (5.3) 7 × 10−5
Current smoker; No. (%) 205 (65) 14 (24) 38 (49) 44 (75) 45 (92) 64 (90) 2 × 10−22
Years since smoking cessationc; mean (SD) 6.6 (4.8) 8.1 (5.2) 6.4 (4.6) 4.3 (3.9) 5.0 (2.2) 3.7 (2.6) 0.002
Pack years; mean (SD) 59.3 (22.5) 55.3 (18.4) 59.0 (25.1) 60.2 (22.3) 60.7 (23.8) 61.3 (22.2) 0.15
Average cigarettes per dayd; mean (SD) 23.3 (12.4) 17.6 (11.6) 17.1 (11.6) 23.7 (12.1) 25.4 (13.1) 26.4 (11.4) 8 × 10−5
Total years smoked; mean (SD) 44.3 (6.7) 42.1 (8.0) 44.2 (6.9) 45.5 (6.2) 45.3 (6.0) 44.7 (5.8) 0.03
BMIe, kg/m2; mean (SD) 27.6 (4.9) 29.2 (4.8) 27.6 (4.7) 27.6 (4.7) 27.7 (5.8) 26.3 (4.4) 0.004
Race, white; No. (%) 307 (97) 58 (98) 73 (94) 59 (100) 47 (96) 70 (99) 0.56f
Sex, female; No. (%) 109 (34) 21 (36) 25 (32) 26 (44) 15 (31) 22 (31) 0.60
Intervention arm, assigned to active; No. (%) 164 (52) 30 (51) 41 (53) 31 (53) 29 (59) 33 (46) 0.79
Asbestos exposure; No. (%) 51 (16) 15 (25) 14 (18) 7 (12) 5 (10) 10 (14) 0.05
Stage; No. (%)        0.66g
Early stage (I/II) 72 (23) 13 (18) 21 (29) 8 (11) 10 (14) 20 (28)  
Late stage (III/IV) 195 (62) 38 (19) 44 (23) 42 (22) 31 (16) 40 (21)  
Unknown stage 49 (16) 8 (16) 13 (27) 9 (18) 8 (16) 11 (22)  
Histotype; No. (%)
Adenocarcinoma 132 (42) 28 (47) 35 (45) 20 (34) 18 (37) 31 (44)  
Squamous cell carcinoma 103 (33) 15 (25) 23 (29) 16 (27) 20 (41) 29 (41)  
Small cell carcinoma 71 (22) 15 (25) 19 (24) 19 (32) 9 (18) 9 (13)  
Any death (through 2015); No. (%) 304 (96) 58 (98) 73 (94) 56 (95) 49 (100) 68 (96) 0.92f
Years between blood draw and diagnosis; mean (SD) 4.3 (2.5) 3.6 (2.5) 4.3 (2.5) 4.5 (2.4) 4.4 (2.6) 4.8 (2.3) 0.02
Controls
  (n = 316) (n = 63) (n = 64) (n = 63) (n = 63) (n = 63) P-trendb
cg05575921, % methylation; mean (SD) 69.3 (14.8) 90.8 (4.0) 78.3 (2.9) 67.6 (2.6) 60.0 (2.0) 49.4 (5.0)
Age at blood draw, years; mean (SD) 63.5 (5.7) 64.6 (6.0) 63.6 (5.2) 64.2 (5.8) 61.7 (5.9) 63.4 (5.4) 0.07
Current smoker; No. (%) 205 (65) 14 (22) 28 (44) 49 (78) 58 (92) 56 (89) 4 × 10−25
Years since smoking cessationc; mean (SD) 6.6 (6.4) 9.0 (7.9) 5.6 (4.3) 4.1 (3.4) 2.8 (2.6) 3.9 (4.5) 0.001
Pack years; mean (SD) 54.2 (24.1) 48.4 (23.5) 53.6 (18.8) 52.9 (23.2) 53.7 (25.8) 62.2 (27.2) 0.004
Average cigarettes per dayd; mean (SD) 21.5 (10.7) 20.9 (8.6) 19.1 (10.9) 21.2 (9.7) 19.7 (9.9) 25.0 (11.9) 0.04
Total years smoked; mean (SD) 42.5 (7.4) 38.6 (8.0) 41.0 (6.9) 43.8 (6.9) 43.2 (7.3) 45.8 (6.0) 1 × 10−8
BMIe, kg/m2; mean (SD) 28.1 (5.5) 29.2 (5.0) 29.3 (6.9) 27.6 (5.4) 27.7 (5.4) 26.6 (4.3) 0.002
Race, white; No. (%) 307 (97) 62 (98) 59 (92) 61 (97) 62 (98) 63 (100) 0.19f
Sex, female; No. (%) 109 (34) 27 (43) 20 (31) 21 (33) 24 (38) 17 (27) 0.19
Intervention arm, assigned to active; No. (%) 168 (53) 27 (43) 32 (50) 36 (57) 38 (60) 35 (56) 0.07
Asbestos exposure; No. (%) 51 (16) 18 (29) 12 (19) 5 (8) 12 (19) 4 (6) 0.003
Any death (through 2015); No. (%) 187 (59) 33 (52) 33 (52) 40 (63) 41 (65) 40 (63) 0.07
  1. Abbreviations: BMI body mass index, NSCLC non-small cell lung cancer, NSCLC, NOS non-small cell lung cancer, not otherwise specified, SD standard deviation
  2. a”Lung cancer cases” includes adenocarcinoma, squamous cell, and small cell, as well as 10 cases for whom histotype was NSCLC, NOS; other NSCLC; unknown or missing
  3. bLinear trend tested using ordinal linear regression for continuous variables and Cochran-Armitage Trend Test for dichotomous variables across decreasing cg05575921 methylation quintiles
  4. cReported for individuals reporting former smoking status at blood draw (n = 111 case-control pairs)
  5. dReported for individuals reporting current smoking status at blood draw (n = 205 case-control pairs)
  6. eBMI is missing for 1 case and 2 controls
  7. fFisher’s Exact test used due to at least 50% of cells containing expected counts of less than 5 per cell
  8. gLinear trend by Cochran-Armitage Trend test for known stage only (early versus late; n = 293 cases)