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Esophageal cancer remains a prominent cancer worldwide. In 2006, 11 345 people died of esophageal cancer in Japan, representing 3.4% of all cancer deaths.(1) Tobacco smoking is the predominant risk factor for esophageal squamous cell cancer.(2–6) However, there are few reports regarding the prognostic impact of smoking on esophageal cancer. Sundelof et al. reported on a Swedish nationwide observational study that evaluated the potential influence of demographic and lifestyle factors on long-term survival in patients with esophageal cancer or gastric cardiac tumors.(7) In their report, prior smoking was a negative prognostic factor for squamous cell carcinoma, but they did not evaluate the impact of smoking in each treatment group. Although the incidence of adenocarcinoma in the lower esophagus has been rapidly increasing in Western countries,(8) no apparent increase in adenocarcinoma has been reported in Japan,(9) where squamous cell cancer is still the predominant histological subtype. Moreover, scarce evidence is available on whether smoking interacts with major treatment modalities, surgery, endoscopic mucosal resection (EMR), or chemoradiotherapy.
The aim of the present study was to clarify the relationship between smoking and the prognosis of esophageal squamous cell cancer. We investigated this question in a retrospective cohort study using data from the Hospital-based Epidemiologic Research Program at Aichi Cancer Center (HERPACC), Japan.
Materials and MethodsPatients. Cases were selected from the database of the HERPACC, conducted at Aichi Cancer Center Hospital (ACCH). Details of the HERPACC have been described elsewhere.(10,11) In brief, 23 408 HERPACC-enrolled, first-visit outpatients treated between January 2001 and November 2005 were asked to provide blood in addition to information on lifestyle factors. Of those who participated, 22 727 (97.1%) subjects completed the questionnaire satisfactorily and were enrolled in the HERPACC. Each patient was asked about his or her lifestyle when healthy and before their current symptoms developed. Most of these questionnaires were gathered from patients prior to the diagnosis of cancer. The study was approved by the Institutional Ethical Committee of ACCH.
In the present study, cases of newly diagnosed esophageal cancer from January 2001 to November 2005 were deemed eligible as case subjects. A total of 375 esophageal cancer patients without a prior history of cancer were observed....