Chronological changes in the morphological features of early gastric cancer, especially recent changes in macroscopic findings.

At the National Cancer Center, 1,300 patients with early gastric cancer were operated on during a period of 21 years, from 1962 to the end of May 1983, and the chronological sequence of the pathological features was analyzed by dividing the 21 years into five periods (I approximately V). The number of elderly patients, especially those above the age of 70 years increased with time, reaching about 20% of all patients in the later period. As to the CMA classification, lesions in A region (antral region) tended to increase, reaching 32.8% in the last period. Lesions on the anterior and posterior wall increased, reaching 20.2% and 30.5%, respectively. Lesions on the greater curvature side were almost unchanged in frequency. The depressed type of carcinoma tended to increase in frequency in the later period, accounting for 75.3% of the total. The depressed type lesions, especially those consisting mainly of IIc element, were therefore subdivided into deep IIc and shallow IIc. In the later period, shallow IIc or not readily detected indistinct IIc increased markedly, reaching 83.3% in Period V. In the initial period, 40% of the lesions were larger than 5 cm. In the later period, lesions larger than 5 cm decreased to 10%, and more than 40% were 2 cm or smaller. Histologically, differentiated and undifferentiated types were found at almost the same frequency. In the later period, the differentiated type became more frequent, reaching as much as 58.2%. Ulcerative lesions (presence of ulcers or ulcer scars in the cancerous lesions) comprised more than 90% of depressed type early gastric cancer, but gradually decreased to 71.9% in the later period. From these findings, early gastric cancer may be said to be changing. Factors contributing to such changes were studied with reference to the progress and multiplication of diagnostic techniques, changes in age composition of the population and changes in environmental factors.