Differences in breast cancer between Japan and the United States.

Two surgically treated series of 375 Japanese and 352 American women with breast cancer were compared with respect to overall survival and recurrence-free survival rates. Recurrence-free survival rates in Japanese women were superior to those in American women. Overall survival rates were also better in Japanese women, although the difference was not nearly as great as for recurrence-free survival. This seemed due to an improved survival after metastasis in the American women. In analyzing recurrence-free survival rates by age, we found that Japanese women 40 to 54 years old had better recurrence-free survival rates than other age subgroups. This age advantage was not observed in American women. For other age groups, there was relatively little advantage in survivorship in the Japanese series.