Table 1.
Baseline characteristics of the study population (Chinese females).
| Cases (n = 374) | Controls (n = 785) | P-valuea | |
|---|---|---|---|
| Age, years [median (Q1–Q3)] | 68.0 (58.8–75.5) | 67.0 (57.3–74.8) | 0.16 |
| Smoking status (n (%)) | < 0.001 | ||
| Never-smoker | 251 (67.1%) | 693 (88.3%) | |
| Ever-smoker | 123 (32.9%) | 92 (11.7%) | |
| Average cigarettes per day [median (Q1–Q3)] | 7.0 (3.0–12.0) | 5.0 (2.0–10.5) | 0.028 |
| Average smoking duration, years [median (Q1–Q3)] | 44.0 (29.0–57.0) | 29.0 (6.0–52.0) | 0.0018 |
| Body mass index (BMI), kg/m2 [median (Q1–Q3)] | 21.6 (19.4–24.8) | 23.3 (20.8–26.7) | < 0.001 |
| Food intake, servings per week [median (Q1–Q3)] | |||
| Meat consumptionb | 11.2 (6.1–18.6) | 13.8 (7.6–23.0) | < 0.001 |
| Fruit consumptionc | 4.9 (1.6–9.3) | 7.4 (2.8–14.0) | < 0.001 |
| Vegetable consumptiond | 14.4 (9.0–24.3) | 17.3 (9.4–29.7) | 0.0047 |
| Type of dwelling [n (%)] | 0.11 | ||
| Flat, 1 room–3 rooms | 120 (32.1%) | 270 (34.4%) | |
| Flat, 4 rooms or more | 185 (49.5%) | 412 (52.5%) | |
| Private property | 66 (17.6%) | 99 (12.6%) | |
| Others | 3 (0.8%) | 4 (0.5%) | |
| Education [n (%)] | 0.67 | ||
| No formal education | 149 (39.6%) | 311 (39.8%) | |
| ≤ 6 years | 112 (32.2%) | 253 (30.0%) | |
| > 6 years | 113 (28.2%) | 221 (30.2%) | |
| History of respiratory diseasee [n (%)] | 0.021 | ||
| Absent | 313 (83.7%) | 693 (88.3%) | |
| Present | 61 (16.3%) | 92 (11.7%) | |
| Family history of cancer [n (%)] | 0.0090 | ||
| None | 258 (69.0%) | 608 (77.4%) | |
| Present-lung cancer | 37 (9.9%) | 42 (5.4%) | |
| Present-other cancers | 79 (21.1%) | 135 (17.2%) | |
| Environmental tobacco smoke (ETS) exposuref [n (%)] | 0.20 | ||
| Absent | 116 (31.0%) | 264 (33.6%) | |
| Present | 258 (69.0%) | 521 (66.4%) | |
| Histologic typeg [n (%)] | N/A | ||
| Non-small cell lung cancer (NSCLC) | 309 (82.6%) | – | |
| Adenocarcinoma | 229 (74.1%) | – | |
| Squamous cell carcinoma | 28 (9.1%) | – | |
| Large cell carcinoma | 4 (1.3%) | – | |
| Unspecified NSCLC | 48 (15.5%) | – | |
| Small cell | 18 (4.8%) | – | |
| Neuroendocrine carcinoma | 5 (1.3%) | – | |
| Other lung cancer | 26 (7.0%) | – | |
| No histological or cytological datah | 16 (4.3%) | – | |
aP-values were obtained using Fisher’s exact test for categorical variables and Mann–Whitney U test for continuous variables.
bFish, chicken, pork, duck, prawns, squid and beef.
cBananas, papayas, apples, oranges, pineapples, watermelons, mangoes, starfruit, jackfruit, plum, cantaloupe, dried prunes, fresh fruit juice and canned peaches.
dWong-nga-pak (Chinese napa cabbage), pak choy (Chinese cabbage), kai lan (Chinese kale), head cabbage, cauliflower, kai choy (Chinse mustard), choy sum (Chinese flowering cabbage), kang kong (water convolvulus), sai yong choy (watercress), por choy (spinach), sang choy (Chinese lettuce), tomatoes, broccoli, French beans, string (long) beans, snow peas, ladies’ fingers, carrot (red) and sweet potato.
eTuberculosis, childhood pneumonia, asthma, chronic bronchitis or emphysema.
fETS exposure is defined as ETS exposure at home more than once per week and/or ETS exposure at work.
gClassification based on ICD-O-3 codes detailed in Supplementary Table 1, unless otherwise specified.
hDiagnosis of primary lung cancer in these subjects were based on radiological examination and after ruling out of the possibility of malignancy from another primary site.