title: A prospective study of tobacco and alcohol use as risk factors for pharyngeal carcinomas in Singapore Chinese.
abstract: BACKGROUND
  Nasopharyngeal carcinoma (NPC) is a rare disease in most populations; however, in areas of Southeast Asia and North Africa and in the Arctic, undifferentiated NPC is the most frequent pharyngeal malignancy. Although smoking and alcohol have been established firmly as synergistic risk factors for other pharyngeal carcinomas, previous studies on the association between these risk factors and NPC have not been consistent. Therefore, the authors analyzed this relation in a cohort of Singapore Chinese, which is a population with a high incidence of NPC.
  
  
  METHODS
  From 1993 to 1998, a population-based cohort of 61,320 Singapore Chinese ages 45 years to 74 years who were free of cancer completed a comprehensive interview on living conditions and dietary and lifestyle factors. By linkage to Singapore population-based registries, the cohort was followed through 2005, and cancer occurrence was determined. The relative risk of NPC and other oropharyngeal carcinomas in the cohort was investigated by using a Cox proportional hazards model.
  
  
  RESULTS
  In total, 173 NPCs and 75 other oropharyngeal carcinomas were observed during 601,879 person-years of follow-up. Smoking for >40 years was associated with a doubled risk of NPC (relative risk, 2.0; 95% confidence interval, 1.2-3.3), whereas smoking intensity, age at smoking initiation, and alcohol consumption were not associated with NPC risk. In contrast, smoking duration, smoking intensity, age at smoking initiation, and alcohol consumption all were associated with an increased risk of other oropharyngeal carcinoma (P for trend, <.0001).
  
  
  CONCLUSIONS
  Smoking and alcohol influenced the risk of NPC and other oropharyngeal carcinomas differently in a high-incidence NPC population. Long-term smoking was a risk factor for NPC, but alcohol consumption was not.
authors.affiliation: The Cancer Center, University of Minnesota, Minneapolis, Minnesota, USA. jfr@ssi.dk
authors.forename: Jeppe T
authors.initials: JT
authors.lastname: Friborg
authors.forename: Jian-Min
authors.initials: JM
authors.lastname: Yuan
authors.forename: Renwei
authors.initials: R
authors.lastname: Wang
authors.forename: Woon-Puay
authors.initials: WP
authors.lastname: Koh
authors.forename: Hin-Peng
authors.initials: HP
authors.lastname: Lee
authors.forename: Mimi C
authors.initials: MC
authors.lastname: Yu
mesh_terms: D000368:Aged; D000428:Alcohol Drinking; D044466:Asian People; D002277:Carcinoma / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010610:Pharyngeal Neoplasms / Q000453:epidemiology*; D011446:Prospective Studies; D012307:Risk Factors; D012846:Singapore / Q000453:epidemiology; D014026:Nicotiana