THE AUTHORS REPLY

[[abstract]]We appreciate the opportunity to respond to the letter by Dr. Rodu (1). In his letter, Rodu asks whether the female head and neck cancer (HNC) cases who used snuff were from the southern United States while the male HNC cases who used snuff were from throughout the United States. In response to this question, we have now performed analyses stratified by sex (female and male) and by region (southern United States and non–southern United States). The following International Head and Neck Cancer Epidemiology (INHANCE) studies or centers (2) were included in the “southern United States” stratum: Houston, Texas; North Carolina (1994–1997); North Carolina (2002–2006); and the Atlanta, Georgia, center of the US Multicenter Study. All other US studies or centers were included in the “non–southern United States” stratum: Seattle, Washington; Iowa; Los Angeles, California; Baltimore, Maryland; New York, New York (Memorial Sloan Kettering Cancer Center); New York State (multicenter); and the Los Angeles, California; New Jersey; and Santa Clara/San Mateo counties, California, centers of the US Multicenter Study. We found that the majority of HNC cases who had ever used snuff but had never smoked cigarettes, regardless of sex, were from the southern region of the United States. Among females, 15 of the 20 (75%) HNC cases who had ever used snuff but had never smoked cigarettes were from the South (Table 1). Among males, 20 of the 24 (83%) HNC cases who had ever used snuff but had never smoked cigarettes were also from the South. Differences in snuff prevalence by region do not necessarily indicate differences in the association with HNC by region. Snuff use was strongly associated with elevated HNC risk in both Southern women (odds ratio = 11.25, 95% confidence interval: 2.14, 59.07) and non-Southern women (odds ratio = 15.91, 95% confidence interval: 1.20, 211.43; Table 1). Among men, we did not observe an association between snuff use and HNC in either region