Serretta et al. performed a study on 99 patients with PSA values between 4–10 ng/mL who received 3-weeks of ciprofloxacin treatment and found that the incidence of cancer in patients with increased PSA after antibiotherapy was higher than that of patients with a decreased PSA (40% vs. 20.3%, respectively, p = 0.02). This evidence concerns the gene KLK3 and cancer.