Table 3.
Characteristics of external study population from the PLCO and the NLSTa
| Variables | PLCO |
NLST |
||
|---|---|---|---|---|
| SPLC No. (%) | All No. (%) | SPLC No. (%) | All No. (%) | |
| Total No. of events (%) | 101 (100.0) | 2963 (100.0) | 93 (100.0) | 2844 (100.0) |
| Follow-up time, y | ||||
| Mean (SD) | 5.5 (3.8) | 2.5 (3.5) | 4.5 (2.7) | 2.6 (3.0) |
| Demographic information | ||||
| Age at IPLC diagnosis | ||||
| Mean (SD), y | 69.1 (6.1) | 71.5 (6.4) | 65.5 (5.9) | 68.4 (6.1) |
| Age groups, No. (%) | ||||
| 55-59 y | 7 (6.9) | 99 (3.3) | 17 (18.3) | 202 (7.1) |
| 60-69 y | 49 (48.5) | 1036 (35.0) | 51 (54.8) | 1433 (50.4) |
| 70-79 y | 40 (39.6) | 1508 (50.9) | 24 (25.8) | 1102 (38.7) |
| ≥80 y | 5 (5.0) | 320 (10.8) | 1 (1.1) | 107 (3.8) |
| Sex, No. (%) | ||||
| Female | 39 (38.6) | 1132 (38.2) | 43 (46.2) | 1202 (42.3) |
| Male | 62 (61.4) | 1831 (61.8) | 50 (53.8) | 1642 (57.7) |
| Race, No. (%) | ||||
| White | 99 (97.0) | 2620 (88.4) | 78 (83.9) | 2578 (90.6) |
| Asian | 0 (0.0) | 70 (2.4) | 4 (4.3) | 45 (1.6) |
| African American | 2 (2.0) | 207 (7.0) | 9 (9.7) | 141 (5.0) |
| Latino | 0 (0.0) | 38 (1.3) | 1 (1.1) | 34 (1.2) |
| Othersb | 1 (1.0) | 28 (1.0) | 1 (1.1) | 46 (1.6) |
| Education, No. (%) | ||||
| High school | 60 (59.4) | 1565 (52.8) | 43 (46.2) | 1510 (53.1) |
| College | 32 (31.7) | 1109 (37.4) | 37 (39.8) | 1007 (35.4) |
| Postgraduate | 9 (8.9) | 285 (9.6) | 11 (11.8) | 276 (9.7) |
| Data missing | 0 (0.0) | 4 (0.1) | 2 (2.2) | 51 (1.8) |
| Tumor characteristics | ||||
| Stage of IPLC, No. (%)c | ||||
| Early stage | 92 (91.1) | 1625 (54.8) | 88 (94.6) | 1761 (61.6) |
| Advanced stage | 9 (8.9) | 1338 (45.2) | 5 (5.4) | 1093 (38.4) |
| Histology of IPLC, No. (%) | ||||
| Squamous cell | 28 (27.7) | 668 (22.5) | 25 (26.9) | 650 (22.9) |
| Adenocarcinoma | 53 (52.5) | 1256 (42.4) | 44 (47.3) | 1173 (41.2) |
| Large cell | 4 (4.0) | 117 (3.9) | 3 (3.2) | 95 (3.3) |
| Small cell | 5 (5.0) | 446 (15.1) | 6 (6.5) | 455 (16.0) |
| Non–small cell carcinoma, NOS, No. (%) | 0 (0.0) | 0 (0.0) | 10 (10.8) | 289 (10.2) |
| Othersd | 11 (10.8) | 476 (16.1) | 5 (5.4) | 182 (6.4) |
| Smoking-related factors | ||||
| Smoking status, No. (%) | ||||
| Former | 53 (52.5) | 1744 (58.9) | 35 (37.6) | 1098 (38.6) |
| Current | 48(47.5) | 1219 (41.1) | 58 (62.4) | 1746 (61.4) |
| Smoking intensitye | ||||
| Mean (SD), cigarettes/d | 26.4 (13.7) | 24.9 (12.1) | 30.4 (10.5) | 29.2 (11.5) |
| Pack-yearse | ||||
| Mean (SD) | 62.8 (34.4) | 57.8 (32.8) | 64.7 (22.3) | 63.5 (26.2) |
| Met the 2013 USPSTF criteria, No. (%)f | ||||
| No | 30 (29.7) | 1266 (42.7) | 3 (3.2) | 332 (11.7) |
| Yes | 71 (70.3) | 1697 (57.3) | 90 (96.8) | 2512 (88.3) |
| Quit-years | ||||
| Mean (SD) | 8.8 (12.2) | 11.4 (13.4) | 3.5 (5.8) | 4.4 (6.7) |
| Clinical factors | ||||
| Prior history of cancer, No. (%)g | ||||
| No | 94 (93.1) | 2735 (92.3) | 87 (93.5) | 2671 (93.9) |
| Yes | 7 (6.9) | 228 (7.7) | 6 (6.5) | 173 (6.1) |
| BMI | ||||
| Mean (SD), kg/m2 | 26.3 (3.6) | 26.6 (4.5) | 27.8 (6.1) | 26.9 (4.8) |
| Data missing, No. (%) | 1 (1.0) | 38 (1.3) | 1 (1.1) | 14 (0.5) |
| Treatments for IPLC | ||||
| Radiotherapy, No. (%) | ||||
| No | 77 (76.2) | 1754 (59.2) | 72 (77.4) | 1792 (63.0) |
| Yes | 24 (23.8) | 1209 (40.8) | 21 (22.6) | 1037 (36.5) |
| Data missing | 0 (0.0) | 0 (0.0) | 0 (0.0) | 15 (0.5) |
| Chemotherapy, No. (%) | ||||
| No | 73 (72.3) | 1444 (48.7) | 60 (64.5) | 1414 (49.7) |
| Yes | 28 (27.7) | 1519 (51.3) | 33 (35.5) | 1406 (49.4) |
| Data missing | 0 (0.0) | 0 (0.0) | 0 (0.0) | 24 (0.8) |
| Surgery, No. (%) | ||||
| No | 17 (16.8) | 2018 (68.1) | 15 (16.1) | 1632 (57.4) |
| Yes | 84 (83.2) | 945 (31.9) | 78 (83.9) | 1212 (42.6) |
The tables stratified by full outcome status are shown in Supplementary Tables 9 and 10 (available online). BMI = body mass index; IPLC = initial primary lung cancer; NLST = National Lung Screening Trial; PLCO = Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial; SPLC = second primary lung cancer; USPSTF = US Preventive Services Task Force.
Others included races from Pacific Islander, American Indian, and missing values.
Disease extent was defined using Surveillance, Epidemiology, and End Results Extent of Disease as local and regional for early stage and distant for advanced stage.
Classification of “other” histology based on International Classification of Diseases–O-3 codes including 8000, 8010, 8012, 8020, 8022, 8031, 8032, 8033, 8246, and 8560 in the PLCO and 8000, 8001, 8010, 8022, 8032, 8033, 8230, 8240, 8249, 8560, and 8980 in the NLST; all confirmed lung cancer cases.
Smoking data from the PLCO closest to initial diagnosis were extracted.
Aged 55-80 years, smoked ≥30 pack-years of smoking, and ≤15 years since cessation.
History of cancer, other than lung, before the time of IPLC diagnosis.