[Topical differences in estrogen receptor content of primary breast cancer]

In 50 primary cancers of the mammary gland, tissue samples from three different parts of each tumor were analyzed for estrogen content by agar gel electrophoresis. In 12 tumors receptor-rich and receptor-poor zones were detected within the tumor for the 4-s fraction, and in 11 tumors for the 8-s fraction. Confidence limits (99%) indicate that these findings might range from 10.4% to 42.5% for the 4-s fraction, and 10.2%-44.1% for the 8-s fraction.