膵臓の早期癌

Early Carcinoma of the Pancreas

はじめに

　消化器系の癌のなかでも，膵臓癌は診断，治療がもっとも困難をきわめる臓器癌の1つであり，現在の時点でその早期癌を論ずるのは時期早尚であるとのそしりをまぬがれないかもしれない．しかし，膨大部領域癌（以下には膨大部癌とよぶ）を含める広義の膵頭部癌―この部位の癌が表1にしめすように，膵臓癌の約70％をしめる¹⁾―に対しては根治手術である膵頭十二指腸切除術が確立，普遍化しているので，早期診断が可能でさえあれば，膵臓癌の半数以上において術後の長期生存が望みうるであろうし，また，最近の10年間に膵臓癌診断のための積極的な検査法がつぎつぎに登場するという進歩があって膵臓癌の早期診断の可能性にも希望がもてはじめてきたことなどの理由から，現段階における膵臓癌の早期像の把握と早期診断へのアプローチを試みることは無意味ではないであろうと思う．膵臓は薄い被膜でおおわれた実質臓器であり，筋層を有する管腔臓器の胃・腸とは局所解剖学的に異なっているので，膵臓の早期癌については早期胃癌のような組織学的定義を適用することはできない．また，膵臓はリンパ系の豊富な臓器であるが，そのリンパ系は複雑多岐であって体系がまだ十分には明確でないので，膵臓の早期癌を組織学的に規定するためにはさらに今後の基礎的検討が必要であろう．

　したがって，この論文では多くの施設の御協力によって調査しえた，1）膵頭十二指腸切除術後の長期生存例，2）早期と考えられる膵臓癌の剖検例3）臨床的に比較的早期と思われる膵臓癌の症例について膵臓癌の早期像をまとめ，ついで比較的新らしい診断技術の診断意義にふれることとした．

　Pictures of pancreatic carcinoma in its early stage are described in this paper based on studies of long-term survivors after pancreatoduodenectomy, of autopsied cases with small carcinoma of the pancreas as well as of cases clinically observed with small carcinoma lesion.

　1) According to collected studies by Maki and Sato in 1965, and by Ishii in 1967, 5-year survival rate after pancreatoduodenectomy in Japan is estimated to be 3～4 per cent.

　2) Reports from 7 institutions show that 11 patients survived over 5 years and 8 patients over 3 years after pancreatoduodenectomy. In 16 of 19 patients chief complaint was jaundice. In 18 patients neither metastasis nor infiltration to other tissues was seen at laparotomy. Tumor under 3 cm in diameter was seen in 70 per cent and that under 2cm in diameter was seen in 50 per cent.

　3) Twelve patients with carcinoma of the head of the pancreas or carcinoma of the periampullary area under 3cm in diameter, were autopsied by Dr. K. Hayashi, Department of Pathology, Nagoya City University. The cause of death in all patients was not tumor-death. In only three of them neither metastasis nor infiltration was seen. In other three patients, slight metastasis to regional lymph nodes and infiltration to the duodenum were found. In the remaining patients, metastases to the liver, lung and lymph nodes of the retroperitoneum or mesocolon were seen. From these results, it is thought that long-term survival could not be expected in about half of patients with small carcinoma of head of the pancreas or carcinoma of the periampullary area with the size of tumor under 2cm in diameter.

　4) Eighteen cases with relatively small carcinoma of the pancreas were presented in the meeting of Japanese Society for Study of Pancreatic Disease in August, 1969. Of these, in 13 cases was the size of tumor under 2 cm in diameter. Twelve were carcinoma of head of the pancreas or carcinoma of the periampullary area and one was carcinoma of the body of the pancreas. In all, metastasis or infiltration was seen at the time of laparotomy. Chief complaint was jaundice in 10 of the 12. In 7 patients, carcinoma of the pancreas was found at laparotomy and in the other 6 carcinoma was suspected by diagnostic procedures.

　5) Diagnostic accuracy of secretin test, pancreozymin-secretin test, exfoliative cytology of duodenal aspirates, hypotonic duodenography, pancreatic scanning, selective angiography are surveyed from several institutions. The results indicate that preoperative diagnosis of carcinoma of the pancreas is greatly improved by aids of these procedures, and small carcinoma of the pancreas can be suspected in some instances. However, it is concluded that further improvement in diagnostic aids including duodenofiberscopy and reflux pancreatography or cholangiography, is essential for detection of early stage of carcinoma of the pancreas.