A comparative study of some pathologic features of mammary carcinoma in Tokyo, Japan and New York, USA.

Epidemiologic and clinical studies conducted in the past 15 years have demonstrated striking differences in the biology of mammary carcinoma among Japanese and American women living in their native countries. These variations have, in part, been related to some differences in the characteristics of the primary tumors between the two groups. As part of a collaborative study we have had an opportunity to compare the stage of disease and to examine and compare histological sections of patients with breast carcinoma treated in 1973-74 at the National Cancer Center Hospital (NCH) in Tokyo and in 1974 at the Memorial Hospital (MH) in New York. The former group consisted of 216 and the latter of 555 carcinomas. Fewer patients in each group had axillary metastases than reported in a prior study of patients treated at MSKCC and in Tokyo 20 to 30 years earlier. Negative axillary nodes were now found in 58% of the MH patients and in 63% of women treated at the NCH. The magnitude of improvement in stage relative to the prior report was similar in both groups. However, it would appear that the change occurred mainly from the mid-1950s to the 1960s in New York and approximately 10 years later in Tokyo. Results of this study confirming prior reports were: (1) higher frequency of colloid and of medullary carcinoma with lymphoid stroma and lesser frequency of lobular carcinoma in the Japanese patients; (2) more intense lymphoid infiltrate in and around primary tumors in Japanese women; (3) higher frequency of rounded or circumscribed tumors in Japanese women; and (4) the more frequent occurrence of intralymphatic tumor emboli within the breast in American women. The difference in the frequency of lobular carcinoma was less striking when comparison was limited to patients with unilateral carcinoma.