The relationship between chronic Chlamydophila (formerly
Chlamydia) pneumoniae infection and lung
carcinoma was investigated. A total of 123 patients who were smokers and diagnosed with lung
carcinoma based on clinical and laboratory (radiological, cytological) findings were examined. Of these patients, 70 had small-cell, 28 squamous-cell and seven
large-cell carcinomas, while 18 had
adenocarcinoma. A total of 123 healthy persons matching patients in age, sex, duration of smoking and locality were chosen as controls. Blood samples (5 ml) were withdrawn at the time of diagnosis and 1 month later. The values between
IgG >/= 512 and
IgA >/= 40 were set as the criteria for chronic Chlamydophila pneumoniae
infections. In male patients with lung
carcinoma, Chlamydophila pneumoniae
IgG antibody titres of >/= 512 and
IgA antibody titres of >/= 40 were found at a higher rate than in the control group. This ratio was not significant for the female patients. In chronic Chlamydophila pneumoniae
infections, Chlamydophila pneumoniae antibody titres with values
IgG >/= 512 and
IgA >/= 40 were found in a total of 62 (50.4 %) cases. Chronic Chlamydophila pneumoniae
infections were seen statistically more often in male patients with
carcinoma who were aged 55 years or younger. This study supports the idea that chronic Chlamydophila pneumoniae
infection increases the risk of lung
carcinoma.