Table 1.

Characteristics of study subjects from the PLCO Cancer Prevention Trial

Lung cancer cases, n (%)Matched controls, n (%)P
Total532 (100)582 (100)
Age at randomization, y
 55–5996 (18)104 (18)0.68
 60–64145 (27)163 (28)
 65–69182 (34)182 (31)
 70–74109 (20)133 (23)
Sex
 Female169 (32)205 (35)0.22
 Male363 (68)377 (65)
Randomization year
 1993–1995220 (41)246 (42)0.99
 1996–1997164 (31)175 (30)
 1998–1999109 (20)120 (21)
 2000–200139 (7)41 (7)
Race
 White470 (88)525 (90)0.06
 Black42 (8)28 (5)
 Asian9 (2)6 (1)
 Pacific Islander9 (2)21 (4)
 American Indian2 (0.4)2 (0.3)
Smoking status
 Never33 (6)109 (19)<0.001c
 Current208 (39)206 (35)
 Former291 (55)267 (46)
Cumulative smoking, pack-yearsa
 1–30126 (25)119 (25)0.95
 30–40136 (27)126 (27)
 40–5042 (8)45 (10)
 50–230195 (39)183 (39)
Years since quittingb
 0.5–15185 (64)167 (63)0.80
 15–53106 (36)100 (37)
BMI
 14.0–18.56 (1)3 (0.5)0.54
 18.6–25.0184 (35)189 (33)
 25.1–30.0231 (44)269 (47)
 30.1–52.5104 (20)112 (20)
Regular aspirin use
 No235 (44)270 (46)0.51
 Yes294 (56)312 (54)
Regular ibuprofen use
 No393 (74)401 (69)0.06
 Yes138 (26)181 (31)
History of chronic bronchitis
 No472 (89)539 (93)0.02
 Yes59 (11)42 (7)
History of emphysema
 No470 (89)550 (95)<0.001
 Yes61 (11)31 (5)
Scarring on baseline chest X-ray
 No461 (87)529 (91)0.02
 Yes71 (13)53 (9)
  • aAnalysis was limited to former and current smokers only.

  • bAnalysis was limited to former smokers only.

  • cBy design, an excess of controls who were never smokers were included.