Abstract
Histologic examination of 115 surgical specimens of gastric cancer irradiated preoperatively in a total tumor dose of 600-4, 000 R of 60Co revealed that various radiation-induced changes were essentially the slime as documented on uterine and breast cancers. The histologies were classified into Grades 0 to III according to the severity and extent of radiation damage, of which Grades II and III were judged to endorse effective irradiation. Such effective changes were identified in 72% of primary tumors of the 115 cases, and the rate of effectiveness increased as the total tumor dose increased (28% for less than 2, 000 R, 74% for 2, 000 R and 88% for more than 2, 000 R). The effect varied with the histologic type of carcinoma, well differentiated adenocarcinomas being least radiosensitive. Irradiation induced also a favorable connective tissue reaction, especially at the advancing front of the tumor in the gastric serosal coat. Lymph node metastases generally had less radiation sensitivity than the primary tumor. Considering also untoward effects of irradiation, which were often manifest at higher doses, a total tumor dose of 2, 000 R was proposed as the level of clinical choice for preoperative ir-radiation of gastric cancer.
