成人日本人における腫瘍性ポリープの自然分布―全大腸内視鏡検診5年間の検討より

Distribution of Neoplastic Polyp in Japanese Adults: Estimation Based on Five Years Experience of Colonoscopic Mass Screening

要旨　成人日本人における大腸腫瘍性ポリープの自然分布を明らかにする目的で，内視鏡検診受診者を対象として疫学的検討を行った．受診者4,959名における腫瘍性ポリープの初回受診時有病率は，早期癌0.32％（16例），腺腫9.3％（459例）であった．進行癌は0.14％（7例）であった．延べ6,839回の検査で発見されたポリープ様病変1,722病巣のうち早期癌，腺腫などの腫瘍性ポリープは897病巣であった．これらの解剖学的分布は，S状結腸が最も多く350病巣(39.0％）を占めた．以下，横行結腸，下行結腸，直腸，上行結腸，盲腸の順であった．この分布は，5mm未満の微小な病巣についても同様であった．これらは一般の成人日本人における自然分布を代表すると考えられる．

　In order to know the natural distribution of neoplastic polyp of the large bowel in Japanese adults, we analized the data obtained from the patients who had received colonoscopy for cancer screening.

　Out of 4,959 patients, 16 early carcinomas (0.32%), 459 adenomas (9.3%) and 7 advanced carcinomas (0.14%) were histologically confirmed. The total number of colonoscopies performed was 6,839 revealing 897 neoplastic polyps such as early carcinoma or adenoma in 1,722 polyp-like elevated lesions. The most frequently involved area was sigmoid colon, in 350 cases (39.0%), followed by transverse colon, descending colon, rectum, ascending colon and caecum in decreasing order. The similar pattern of distribution was seen as well for the lesions smaller than 5 mm in diameter. Regarding the relation between the size and color of the lesions, the frequencies of histological atypia and early carcinoma increased as the size increased and reddish discoloration existed.

　The distribution of neoplastic polyps of the large bowel based on our results, we think, is consistent with natural distribution of neoplastic polyps of the large bowel in Japanese adults in general.