全国集計からみたpm胃癌

Pm Gastric Cancer: The results of nationwide collection

　早期胃癌がどのようにして進行胃癌に進展するかということは，病理学者にとっては大変興味ある課題であろうが，臨床家にとっても大変重要な問題である．亡くなられた佐野量造博士は，胃癌の深達度別の頻度を潰瘍型と隆起型に分けて調べた結果，両型ともにmからsに至るまでの頻度が直線的にならなく，pmの癌が手術例でもっとも少ない結果となっていることから，おそらく，m・smの早期癌のうち，その発育が遅くてpmにとどまるものと，早期癌の段階から直ちにssおよびsに浸潤を進める速度の速い癌があることに原因しているものであろうと述べている¹⁾．その裏づけとして，pm癌の5年生存率は，ss・sの群よりも，m・smの群に近い数字を示していることを挙げており，pm癌を準早期胃癌と呼ぶことができると提唱している．

　さて，佐野博士のこれらの業績は，すべて国立がんセンターの手術例をもとになされたものであるが，全国集計の結果をこのような観点からみたらどうであろうか．1969年に胃癌研究会が中心となって，全国の主要病院の外科の絶大な協力のもとに，胃癌の全国登録調査が開始されたが，今回は，すでに集計公表された部分²⁾を中心に，若干印刷中のものも借用させていただいて，ご参考に供したいと思う．

　Characteristics of pm gastric cancer have been studied out of the results collected from nationwide registrations of gastric cancer cases. During the 6 years 1963～1966 and 1969～1970, pm cancer of the stomach amounted to 3,045 among 26,375 gastrectomized cases registered during this period. The incidence of pm cancer was 11. 5 per cent; m cancer,6.3 per cent; sm cancer, 7.9 per; ss cancer was 12.7 per cent in frequency. The incidence of pm cancer in our series was greater than that reported by Sano who had examined gastrectomized cases in the National Cancer Center. However, when progress and propagation of early diagnosis f or gastric cancer in recent years resulting in ever increasing number of early cancer detection is taken into account, we cannot deny what Sano assumed, that is, once cancer invades the muscularis propria from the submucosal layer, a far greater number of cancer lesions infiltrate rapidly the serosa than those remaining relatively long in the muscularis propria.

　Lymph node metastasis of pm gastric cancer was as follows: n (-) 36.0%; n₁ (+) 22.5%; n₂ (+) 9.0%; n₃ (+) 1.7%; and n₄ (+) 0.2%. As compared with cancer in m, sm and ss, lymph node metastasis definitely increased in number when cancer developed from the mucosa into the submucosa. Then metastasis increased in a stepwise manner.

　Of 632 cases of pm cancer cases resected during the 4 years since 1963, 390 cases survived for 5 years. The relative 5-year-survival rate was 70.2 per cent. This rate was just midway between that of sm cancer (90.3%) and of ss cancer (49.8%). The relative 5-year-survival rate of 273 pm cancer cases with no lymph node involvement was 88.1%, a figure close to that of sm cancer. We have also compared our results with those of Sano, who reported that results of treatment for pm cancer were close to those for sm cancer.