The overall pooled estimates from C. pneumoniae studies revealed that C. pneumoniae infection is a risk factor among lung cancer patients who are IgA seropositive (OR = 1.88, 95% CI = 1.30–2.70, p < 0.001) and IgG seropositive (OR = 1.50, 95% CI = 1.10–2.04, p = 0.010). The gene discussed is CD79A; the disease is lung carcinoma.