Receptors for epidermal growth factor and steroid hormones in human breast cancer

Epidermal growth factor (EGF) seems to play an important role in regulating the proliferation of human breast cancer. Fifty-five primary breast tumors and 7 lymph node metastases were simultaneously assayed for the presence of EGF receptors (EGFR), estrogen receptors (ER), and progesterone receptors (PR). Overall, 42% (23/55) of the tumors were EGFR positive. EGFR were more frequently present in ER- and PR-negative than in ER- and PR-positive tumors. In particular, a negative correlation between EGFR and PR (chi 2 = 6.8; p greater than 0.01) was observed. All metastatic tumors were EGFR negative, and in all cases but 1 the levels of EGFR were higher in metastatic than in primary tumors. Our results suggest the presence of a subclass of breast tumors, the growth of which is primarily regulated by EGF or EGF-like substances rather than by steroid hormones. In this group, not amenable to endocrine therapy, EGF receptors should represent a target for therapeutic intervention.