DISTRIBUTION OF GSTM1 NULL GENOTYPE IN RELATION TO GENDER, AGE AND SMOKING STATUS IN JAPANESE LUNG-CANCER PATIENTS

GSTM1 gene deficiency has been shown to occur in approximately half of the populations of various ethnic origins and has been implicated as a factor for elevated risk for lung cancers. However the results have been variable or even conflicting between the studies, In an attempt to explore the reason for such a diversity, we studied the distribution of GSTMI genotypes in relation to gender, age and smoking status in 447 Japanese lung cancer patients and 469 community controls, We found: (1) that in squamous and small cell carcinomas GSTM1 null genotype distributed markedly more in females than males especially among the patients aged < 70 years (male 57.4%, female 100.0%); (2) that GSTM1 null genotype distributed generally more in patients aged < 70 years (58.3%) than those aged greater than or equal to 70 years (50.0%) irrespective of histologies except for small cell carcinoma; and (3) that proportion of GSTM1 null genotype increased dependent on the extent of tobacco smoke exposure in male patients having squamous and small cell carcinomas aged < 70 years, and remained high but independent of the smoking index in adenocarcinoma and unchanged in never- or exsmokers from the control level (48.6%). The present study thus suggests that composition of GSTMI genotypes in patients is significantly affected by gender, age and smoking status, which should be taken into consideration in any attempt to determine the association of GSTM1 genotypes for risk assessment, With the diverse of GSTM1 null genotype variability between patients of different histologies, our results were also suggestive of different carcinogenic involvement of GSTM1 deficiency among different histological cell types.