Serological evidence of an association betweenChlamydia pneumoniae infection and lung cancer

Abstract

Epidemiological evidence suggests that airway obstruction is an independent risk factor for lung cancer and that this cannot be explained by active or passive smoking alone. Chlamydia pneumoniae infection has been associated with chronic bronchitis and its exacerbates. Our aim was to evaluate the association between chronic C. pneumoniae infection and risk of lung cancer among male smokers. Smoking males with lung cancer (n 5 230) and their age-and locality-matched controls were selected among participants of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. The presence of C. pneumoniae infection was assessed by analyzing specific antibodies and immune complexes in 2 serum samples collected with a 3-year interval before the lung cancer diagnosis. The diagnosis of chronic infection was based on stable levels of positive specific IgA antibody (titer H 16) and immune complex (titer H 4). Relative risks were estimated by odds ratios (OR) adjusted for age, locality and smoking history by a conditional logistic regression model. Markers suggesting chronic C. pneumoniae infection were present in 52% of cases and 45% of controls and hence were positively associated with the incidence of lung cancer (OR 1.6; 95% confidence interval [CI] 1.0-2.3). The incidence was especially increased in men younger than 60 years (OR 2.9; 95% CI 1.5-5.4) but not in the older age group (OR 0.9; 95% CI 0.5-1.6). Before concluding that C. pneumoniae infection is a new independent risk factor for lung cancer, corroboration from other studies with larger number of cases and longer follow-up is needed. Int. J. Cancer 74:31-34.Chlamydia pneumoniae is a common intracellular bacterium that causes pneumonia and other respiratory infections world-wide. Like all Chlamydia organisms, it has a tendency to cause persistent and chronic infections. C. pneumoniae has been serologically associated with chronic lung diseases such as chronic bronchitis (von Hertzen et al., 1995) and adult onset asthma (Hahn et al., 1991), as well as and with atherosclerosis (Saikku et al., 1988), in which the organism has been demonstrated in atherosclerotic plaques (Kuo et al., 1993). Chronic bronchitis has been suggested as an independent etiologic factor in lung cancer (Osann, 1991), the effect of which cannot be explained by either active or passive exposure to cigarette smoke. Smoking does, however, appear to promote chronic C. pneumoniae infection, probably through immunosuppression (Karvonen et al., 1994a).In Finland, nearly 30,000 male smokers were followed for 5-8 years in 1985-1993 in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC Study Group, 1994). We analyzed baseline and 3-year follow-up serum samples from 230 men diagnosed with lung cancer after the third year and their age-, timeand locality-matched controls for C. pneumoniae-specific IgG and IgA antibodies and immune complexes to study the association between markers suggestive of chronic C. pneumoniae infection and lung cancer. MATERIAL AND METHODS Base population and follow-u...

Chlamydia pneumoniae infection and the risk of female early‐onset lung cancer

“…5,10 In our study, C. pneumoniae-specific immune complexes and both IgG and IgA antibodies were associated with female lung cancer. A previous study of male Finnish smokers 5 indicated that chronic C. pneumoniae infection was associated with subsequent diagnosis of squamous cell and small cell carcinomas but not with adenocarcinoma.…”

“…1 Although the relation between respiratory Chlamydia psittaci infection (avian exposure) and female lung cancer remains open, [2][3][4] C. pneumoniae infection has been repeatedly shown to be associated with lung cancer in male smokers as defined by serum cotinine. [5][6][7] We have now evaluated the association between past infection with C. pneumoniae and female lung cancer in a case-control study nested in a cohort of 650,000 fertile Finnish women established in 1983.…”

“…Chlamydia-specific IgG immune complexes (IC) were analysed as described previously. 5 Current smoking was defined by serum cotinine levels using a quantitative ELISA modification according to the manufacturer's instructions using the cutoff level of Ն20 ng/ml for active smoking (STC Technologies, Bethlehem, PA). Relative risks with their 95% confidence intervals (CIs) were estimated as odds ratios (ORs) by conditional logistic regression.…”

Risk of cervical cancer associated with Chlamydia trachomatis antibodies by histology, HPV type and HPV cofactors

“…13,[23][24][25] In this study we also found that histologic type, not HPV DNA type, is a more important parameter in the determining association between C. trachomatis and cervical cancer. Similarly, in two recent prospective studies of the association between C. pneumoniae antibodies and lung cancer, elevated risks were found for squamous cell cancers but not adenocarcinomas of the lung, 26,27 though another study did not find this difference by histologic type. 28 It may be that the underlying pathogenic mechanisms of Chlamydia in cancer are specific to squamous cell cancers.…”

Lack of association between chronic Chlamydophila pneumoniae infection and lung cancer among nonsmoking Chinese women in Singapore

“…These studies were performed in Caucasian populations and primarily among male smokers. 1,3,4 To our knowledge, only 1 study has demonstrated an association between chronic infection and lung cancer among women. 2 This study, nested within the Finnish Maternity Cohort, observed a smoking-adjusted 2-fold increase in risk of early-onset lung cancer among women with elevated IgA (Ͼϭ64) or IgG (Ն128) titers.…”