Article Figures & Data
Tables
- Table 1.
Summary of nested case-control studies of C. pneumoniae and lung cancer risk with blood collected before lung cancer diagnosis in cases and a comparable time in controls
First author, year, location Population Number of subjects Time between blood sampling and lung cancer diagnosis/censoring (y) Variables adjusted for in multivariate models Laurila, 1997 (23), Finland Male smokers involved in a randomized trial of β-carotene and α-tocopherol 230 cases/230 controls 3-8 (median = 6.1) Years of smoking and cigarettes smoked per day Anttila, 2003 (28), Finland Women in 1st trimester of pregnancy in Finnish Maternity Cohort 58 cases/287 controls 1.6-16.7 (mean = 9.1) Current smoking defined by serum cotinine levels Littman, 2004 (29), USA Men and women involved in a randomized trial of β-carotene and retinol 508 cases/508 controls 0-16 (median = 9) Years of smoking, cigarettes smoked per day, education, and body mass index (kg/m2) - Table 2.
Summary of case-control studies of C. pneumoniae and lung cancer risk with blood sampled at or after lung cancer diagnosis and at a comparable time in the controls
First author, year, location Number of cases/controls Case population/selection Control population/selection Matching factors Confounders adjusted for Jackson, 2000 (26), USA 148 cases/148 controls Men in WA state diagnosed with LC between 5/93 and 7/96, identified through the SEER cancer registry. Population based. Men without LC identified through random digit dialing. Age (5-y categories) and gender Smoking status (current or former), pack-years (<40 or ≥40) and education Koyi, 2001 (25), Sweden 177 cases/C1 = 68, C2 = 111 Diagnosed with LC at a single hospital between 2/97 and 2/98. Hospital based. C1: Consecutive blood donors who were former or current smokers presenting at the same hospital during spring 1998 (exclusions: history of MI, medication for hypertension, or other CV diseases). C2: Participants in a study of current and ex-smokers >70 y old None None Kocazeybek, 2003 (27), Turkey 123 cases/123 controls Smokers admitted to an Istanbul hospital with a diagnosis of LC between 6/98 and 7/2000. Hospital based. Healthy hospital staff, relatives of the patients, blood donors, or persons with similar age, sex, and smoking habits and not having any medical treatment for a local or systemic disease and not admitted to the hospital in the previous 2 months Age (5-y age group), sex, living environment (i.e., province), smoking status (former or current), duration (10-y categories), and quantity of cigarettes smoked (4 categories) In primary analyses, none. Abbreviations: WA, Washington; LC, lung cancer; MI, myocardial infarction; CV, cardiovascular; SEER, Surveillance, Epidemiology, and End Results; C1, control group 1; C2, control group 2.
- Table 3.
Selected results from studies on C. pneumoniae infection and lung cancer risk
First author, year, location Definition of chronic infection Overall results Findings by age at diagnosis/reference Other subgroup findings Comments Laurila, 1997 (23), Finland “Strong or moderate” evidence* 1.6 (1.0-2.3) 50-59 y: OR, 2.9; 95% CI, 1.5-5.4 Squamous or small cell cancer: OR, 1.7; 95% CI, 1.0-2.8 ≥60 y: OR, 0.9; 95% CI, 0.5-1.6 Follow-up <5 y: OR, 2.0; 95% CI, 1.1-3.6 ≥5 y: OR, 1.2; 95% CI, 0.5-2.5 Jackson, 2000 (26), USA IgA ≥ 16 1.4 (0.9-2.3)† <60 y: OR, 2.7; 95% CI, 1.2-5.9 Association stronger among current smokers <60 y at diagnosis than former smokers: Blood specimens were obtained from only 47% of cases who completed interviews in counties where blood was collected, mainly because of death or illness. ≥ 60 y: OR, 0.7; 95% CI, 0.3-1.4 Current: OR, 4.6; 95% CI, 1.4-13.7 Former: OR, 1.5; 95% CI, 0.5-4.8 Koyi, 2001 (25), Sweden IgA ≥ 64‡ ORs were stronger among men than women (except for IgA ≥ 64 with cases compared with C2). Possible confounding by age, which differed between the case and control groups Cases vs. C1 9.9 (4.6-22.2)† For IgG ≥ 512: Cases vs. C2 5.0 (3.2-7.9)† C1: Men: OR, 10.2; 95% CI, 4.0-27.9 IgG ≥ 512‡ C1: Women: OR, 1.7; 95% CI, 0.5-7.0 Cases vs. C1 4.2 (2.1-8.9)† C2: Men: OR, 3.6; 95% CI, 2.0-6.7 Cases vs. C2 2.5 (1.6-4.0)† C2: Women: OR, 1.3; 95% CI, 0.6-2.6 Kocazeybek, 2003 (27), Turkey IgG ≥ 512 and IgA ≥ 40§ 4.6 (2.3-10.2)† Men < 55 y: OR, 18.0; 95% CI, 4.6-154 Men: OR, 5.3; 95% CI, 2.4-12.9 Possible selection bias; possible exposure misclassification due to use of higher value in cases only Men ≥ 55 y: OR, 1.0; 95% CI, 0.3-3.3 Women: OR, 2.0; 95% CI, 0.3-22.1 Anttila, 2003 (28), Finland IgA ≥ 16 1.6 (0.9-2.8) ORs for IgG antibody titers (≥32 and ≥128) and IC (≥2 and ≥4) were of similar magnitude (1.7 to 2.2) Mean age of cases at diagnosis was 41 y (range 22-53 y) IgA ≥ 64 2.1 (1.2-3.9) Littman, 2004 (29), USA IgA ≥ 16 1.2 (0.9-1.6) Male asbestos-exposed workers: OR, 1.9; 95% CI, 0.9-3.7; former smokers: OR, 2.1; 95% CI, 1.1-4.1; squamous cell carcinoma: OR, 1.7; 95% CI, 1.1-2.8 Abbreviations: IC, immune complexes; OR, odds ratio; CI, confidence interval; CI, control group #1 (see Table 2); C2,control group #2 (see Table 2).
↵* Blood sampled at baseline and at 3-y follow-up used to assess exposure. Strong evidence defined as IgA antibodies ≥16 and IC ≥ 4 in both samples, moderate evidence defined as IgA ≥ 16 in both samples or IC ≥ 4 in both samples and IgA ≥ 16 in second sample.
↵† Calculated from data presented in published articles.
↵‡ Final titer defined as higher value of blood sampled at diagnosis (all) or 3 months later (n = 127).
↵§ Final titer defined as higher value of blood sampled at diagnosis or 1 month later.