A CD4+/CD8+ ratio lower than 25 within 1 year of lung cancer diagnosis showed an association with lung cancer risk of borderline statistical significance (OR=2.15, 95% CI: 1.00–4.59), but this relationship was not seen at 1–2 years before lung cancer diagnosis (OR=1.07, 95% CI: 0.49–2.36). This evidence concerns the gene CD4 and lung carcinoma.