EGF-R EXPRESSION IN DUCTAL BREAST-CANCER - PROLIFERATION AND PROGNOSTIC IMPLICATIONS

We studied epidermal growth factor receptor (EGF-R) expression in rela tion to steroid receptor status, flow cytometric DNA content and S-pha se fraction (%S) in a selected case series of 129 ductal primary opera ble breast cancer to determine the possible role of EGF-R in prognosis assessment. EGF-R expression was positively related with proliferatio n activity, suggesting that EGF-R could be involved in the regulation of breast cancer cell growth. We found about 80% of highly proliferati ng DNA aneuploid tumors in the EGF-R positive category, while the EGF- R negative tumors showed a lower frequency of highly proliferating DNA aneuploid tumors (57%), confirming the important role of EGF-R in bre ast cancer aggressiveness and progression. No relationship between EGF -R expression and steroid receptor status was observed. To better unde rstand how EGF-R and estrogen receptor (ER) operate together to stimul ate breast cancer cell growth we analyzed the %S in the two groups of ER negative (ER-) and ER positive (ER+) tumors, stratifying the patien ts on the basis of EGF-R tumor positivity. Here breast tumor prolifera tion activity seems mainly to be induced by the stimulus of EGF-R, the %S values of the EGF-R negative tumors in the ER- and ER+ groups bein g 6.1 and 6.9%, respectively. Instead, the median %S of EGF-R positive tumors was 10% in the ER- class and 14% in the ER+ group. The analysi s of the percentages of 5-year patient disease free survival were 84% for patients with EGF-R negative tumors and 61% for patients with EGF- R positive lesions, respectively. The data reported here further show the crucial role of EGF-R in breast cancer cell growth and that the EG F-R overexpression is indicative of a poor prognosis.