Glutathione S-transferase M1 and susceptibility to nasopharyngeal carcinoma

Genetic polymorphisms for enzymes that metabolize tobacco smoke have been r eported to determine susceptibility to several smoking-related cancers, inc luding cancers of the lung, bladder, and head and neck. Glutathione S-trans ferase M1 (GSTM1) detoxifies benzo(a)pyrene and other carcinogens in tobacc o smoke. Approximately 50% of Caucasians lack the GSTM1 gene. Because the m ost common type of nasopharyngeal canter (NPC), squamous cell carcinoma, is related to smoking, we sought to determine whether GSTM1 is associated wit h risk for NPC, Cases (n = 83) were from a population-based study conducted from 1987 to 1993 at five cancer registries in the United States. Random-d igit dialing controls (n = 114) were matched to the cases for age, sex, and registry. Subjects participated in a phone interview and blood draw. Absen ce of GSTM1 was associated with increased risk for NPC (odds ratio = 1.9, 9 5% confidence interval = 1.0-3.3 for all cases; and odds ratio = 1.7, 95% c onfidence interval = 0.8-3.5 for squamous cell cases). This relationship wa s not modified by smoking history, but stronger relationships between gluta thione S-transferase and NPC were suggested among subjects who used alcohol more frequently than others, older subjects (50 or more years of age), and women relative to men. These data indicate that absence of GSTM1 moderatel y increases risk for NPC and add to growing evidence that GSTM1 is a determ inant of risk for several smoking-related cancers.