Table 3.

Selected results from studies on C. pneumoniae infection and lung cancer risk

First author, year, locationDefinition of chronic infectionOverall resultsFindings by age at diagnosis/referenceOther subgroup findingsComments
Laurila, 1997 (23), Finland“Strong or moderate” evidence*1.6 (1.0-2.3)50-59 y: OR, 2.9; 95% CI, 1.5-5.4Squamous or small cell cancer: OR, 1.7; 95% CI, 1.0-2.8
≥60 y: OR, 0.9; 95% CI, 0.5-1.6Follow-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), USAIgA ≥ 161.4 (0.9-2.3)<60 y: OR, 2.7; 95% CI, 1.2-5.9Association 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, 0.3-1.4Current: OR, 4.6; 95% CI, 1.4-13.7
Former: OR, 1.5; 95% CI, 0.5-4.8
Koyi, 2001 (25), SwedenIgA ≥ 64ORs 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. C19.9 (4.6-22.2)For IgG ≥ 512:
Cases vs. C25.0 (3.2-7.9)C1: Men: OR, 10.2; 95% CI, 4.0-27.9
IgG ≥ 512C1: Women: OR, 1.7; 95% CI, 0.5-7.0
Cases vs. C14.2 (2.1-8.9)C2: Men: OR, 3.6; 95% CI, 2.0-6.7
Cases vs. C22.5 (1.6-4.0)C2: Women: OR, 1.3; 95% CI, 0.6-2.6
Kocazeybek, 2003 (27), TurkeyIgG ≥ 512 and IgA ≥ 40§4.6 (2.3-10.2)Men < 55 y: OR, 18.0; 95% CI, 4.6-154Men: OR, 5.3; 95% CI, 2.4-12.9Possible selection bias; possible exposure misclassification due to use of higher value in cases only
Men ≥ 55 y: OR, 1.0; 95% CI, 0.3-3.3Women: OR, 2.0; 95% CI, 0.3-22.1
Anttila, 2003 (28), FinlandIgA ≥ 161.6 (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 ≥ 642.1 (1.2-3.9)
Littman, 2004 (29), USAIgA ≥ 161.2 (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.