大腸のポリープと癌

Polyp and Cancer of the Large Bowel

はじめに

　大腸のポープを癌との関連について考察するとき，次の3つの問題点が注目されるのであろう．すなわち，①悪性ポリープの頻度，②良性ポリープの悪性化の可能性，③大腸の進行癌への移行とその頻度である．

　いずれも難しい問題であり，古くから多くの論争があるが，ここにわれわれの経験した症例を検討し，筆者の現在の考えを述べたいと思う．

　Relationship between polyp of the large bowel and its cancer has been correlated on the 163 cases of polyp of the large bowel (more than 0.5 cm in diameter) resected in the authors’ institution.

(1) Polyp of the large bowel is classified into five groups according to the degree of histological atypia.

(2) Incidence of malignant polyp (cancer) is 12 per cent. When those polyps needing clinical management as cancer suspect (group IV) are added, the incidence rises up to 22 per cent.

(3) According as the diameter of polyp becomes larger, the degree of atypia becomes manifest and malignant polyps increase in number. Polyps having the diameter of more than 2cm are malignant in 32.4～53 per cent groups).

(4) Sex and age distribution of polyp and cancer is approximately parallel to each other. Polyp is a little more fund in the rectosigmoid and sigmoid.

(5) No noticiable correlation has been found between the forms (sessile or pedunculated) and incidence of malignancy.

(6) As compared with other groups, polyp associated with multiple cancer of the large bowel shows higher incidence of and tendency to malignancy.

(7) Investigation of individual polyps, or in other words, study of histological findings in polyps, atypical or cancerous, as well as investigation of multiple cancer of the large bowel seems to support the view that a part of polyp becomes malignant.

(8) Of 23 cases of polyp-cancer, including polyp associated with multiple cancer of the large bowel, at least 17 cases are presumed to be canceration of benign polyps.

(9) Transition from polyp-cancer to ordinary advanced carcinoma has been investigated. At least more than 8 per cent of advanced carcinoma seem to originate from polyp.

(10) Various reports about the relationship between polyp and cancer have been studied.