Genotype Announcement to Japanese Smokers Who Attended a Health Checkup Examination

BACKGROUND Genotype announcement may be one of the effective methods to induce smoking cessation, but the studies are limited throughout the world. METHODS Subjects were smokers who attended a health checkup examination provided by a local government in Hokkaido, Japan, 2003. Those who agreed to know their genotypes were informed of the genotypes of glutathione S-transferease (GST) M1 present/null, GSTT1 present/null, and NAD(P)H:quinone oxidoreductase 1 (NQO1) C609T (Pro187Ser). RESULTS Out of 143 smokers (92 males and 51 females), 101 individuals participated in the present study. A postal questionnaire one year after the genotype announcement found that 8 persons (6 males and 2 females) of 41 respondents had quitted smoking. Two of 8 quitters stated that they had quitted smoking due to the announcement. There were none who regretted the genotype tests. CONCLUTION Although the cessation rate, 7.9% (8/101) at least, was not marked, no harmful effects were observed among the respondents.

Genotype announcement for smokers is a new approach to induce smoking cessation. To date only two controlled studies in the United States 1,2 and one case series study at a Japanese worksite 3 have been reported in the world. The announced genotypes were CYP2D6, 1 GSTM1, 2 and L-myc, 3 of which functional polymorphisms were reportedly associated with the susceptibility to carcinogens in tobacco smoke.
In the present study, the effects of genotype announcement were examined for smokers who attended a health checkup examination run by a rural local government in Hokkaido, Japan. The announced genotypes were of three polymorphisms, glutathione S-transferease (GST) M1 present/null, GSTT1 present/null, and NAD(P)H:quinone oxidoreductase 1 (NQO1) C609T. These genes code carcinogen detoxifying enzymes.
Study subjects were sampled from annual checkup examinees run by a local government in Hokkaido on the consecutive three days of August 2003, whose study framework was described in the previous paper. 4 Informed consent of genotype announcement was obtained individually from each smoker, using a booklet on genotype and susceptibility to tobacco carcinogen. For the smokers who agreed the donation of 0.5ml residual blood, genotypes with an explanation note were mailed 3 months later after the enrollment. Current smoking habits were asked one-year after the announcement by mail. Repeated mailing to the unrespondents was not conducted to giving the potentially unpleasant and troublesome pressure to the participants. GSTM1 present/null, GSTT1 present/null, and NQO1 C609T were genotyped by a triplex PCR with confronting two-pair primers. 5 The genotype frequency of Of the 101 smokers, 41 (40.6% of 101) responded to the questionnaire. Eight (7.9% of 101 smokers, 95% confidence interval: 3.5-15.0) stated to have quitted smoking; 2 females due to the results of genotype tests, 1 male due to sickness, 4 males due to maintaining health, and 1 male due to no reason. The number of genotypes with no enzyme activity were significantly related to smoking cessation (Fisher's exact test, p=0.05) between those harboring 0 or 1 genotypes with no enzyme activity (4.3%, 3/70) and those harboring 2 or 3 genotypes with no enzyme activity (16.7%, 5/30). There were no participants who regretted the participation, as shown in Table 2.
Although the response rate was low, this study found that the cessation rate was 7.9% at least. Because this study had no controls, the precise excess cessation due to the genotype announcement was not evaluable. However, two participants stating the cessation due to genotype tests and some of four participants stating the cessation due to maintaining health might be fully or partly induced to quit smoking through the genotype announcement.  Some researchers warn that genotype announcement may be potentially harmful even in the case of polymorphism genotypes. However, there are no reports indicating that the announcement of polymorphism genotypes made serious problems among the announced persons. It is quite different from the announcement of hereditary disease genotypes.
In conclusion, the present study found that about 8% of smokers quitted smoking one year after their genotypes were announced with mail. The effects of genotype announcement on smoking behavior under a face-to-face approach remain to be studied.