Ethnic difference in the distribution of CYP1A1*2C variant has been demonstrated in lung cancer patients, while few reports are available for CYP1A1*4. Frequencies of CYP1A1*2C ranged from 2.2% to 8.9% in Caucasians and was about 19.8% in Japanese, while CYP1A1*4 allele was found in 2% to 5.7% of a Caucasian population [24–27]. The gene discussed is CYP1A1; the disease is lung cancer.