中・下咽頭領域の表在癌の危険因子―アルコール依存症男性の内視鏡検診に基づく症例対照研究

Risk Factors of Squamous Cell Carcinoma in the Oropharynx, Hypopharynx, and Epilarynx of Japanese Alcoholic Men: A Case-control Study Based on an Endoscopic Screening Program

要旨　アルコール依存症患者の口腔咽喉癌の症例対照研究を行った．内視鏡による口腔咽喉観察と食道ヨード染色を併用した5,210例の初回内視鏡検診から診断された55例の口腔咽喉癌〔43例は中・下咽頭癌（EP14例，SEP19例，より深い浸潤10例），13例は舌・口底・歯肉・声帯の癌（1例は中・下咽頭癌と重複）〕を対象症例とした．年齢と初回検診時期を1対5でマッチさせた275例を対照とした．中・下咽頭癌の危険因子は食道癌と類似し，ALDH2へテロ欠損型の非常に強い影響（odds比6.66）と，ADH1Bホモ低活性型（odds比3.15），フラッシャー（odds比2.71），赤血球MCVの増大（odds比3.60），高度の喫煙（odds比2.08）の影響がみられた．口腔咽喉癌全体でも類似のリスクを示したが，舌・口底・歯肉・声帯の癌でこれらの因子の影響は明らかでなかった．

　SCC（squamous cell carcinoma）in the OHE（oropharynx, hypopharynx, and epilarynx）are frequently diagnosed at early superficial stage by endoscopic screening in Japanese alcoholic men, and can be mostly treated by endoscopic mucosectomy. We conducted a nested case-control study based on the results of the endoscopic screening of 5,210 Japanese alcoholic men aged 40 years or over. 43 cases of SCC in the OHE were detected and 215 cancer-free controls matched for age and initial examination time with case : control ratio of 1 : 5 were randomly selected. A conditional logistic model showed that the odd ratio for SCC in the OHE was 6.66（95％CI ; 3.27～13.6）in aldehyde dehydrogenase-2（ALDH2^*1/^*2）heterozygotes versus ALDH2^*1/^*1 homozygotes, 3.15（1.56～6.36）in alcohol dehydrogenase-1B（ADH1B^*1/^*1）homozygotes versus ADH1B^*1/^*2 heterozygotes or ^*2/^*2 homozygotes, 2.71（1.36～5.43）in patients with current or past alcohol flushing compared with those who had never experienced alcohol flushing, 3.60（1.69～7.65）in those with a MCV（mean corpuscular volume）≧106 fl compared with those with an MCV＜106 fl, and 2.08（0.94～4.63）in those who smoked 20 cigarettes or more per day compared with those who smoked 0～19 cigarettes per day. The OHE and esophagus of Japanese alcoholic men shared several common risk factors for developing SCC.