Expression of epidermal growth factor receptors associated with lack of response to endocrine therapy in recurrent breast cancer.

Epidermal growth factor receptors (EGFR) and oestrogen receptors (ER) were analysed in 221 patients with primary operable breast cancer by means of radioligand assays. After median follow-up of 24 months (range 3-60 months), there had been recurrences in 99 patients, of whom 72 (median age 56 years, range 32-77 years) received tamoxifen alone as first-line treatment for recurrence. 20 patients (28%) showed a response to this therapy and 52 (72%) did not. Of 32 ER-positive tumours, 12 (37.5%) showed an objective response to tamoxifen compared with only 2 of 40 (5%) ER-negative tumours (p less than 0.005). Of 35 EGFR-positive tumours, 3 (8.5%) achieved an objective response compared with 11 of 37 (30%) EGFR-negative tumours (p less than 0.05). Only 1 of 28 EGFR-positive, ER-negative tumours achieved an objective response. Including patients whose disease remained stable for more than 6 months with the responders, however, EGFR status was a better predictor of response to tamoxifen; 15 of 37 EGFR-negative patients and 5 of 35 EGFR-positive patients responded (p less than 0.01), compared with 13 of 32 ER-positive and 7 of 40 ER-negative patients (not significant). EGFR expression is a highly significant marker of poor prognosis in patients with breast cancer; it appears to be as good a predictor as ER for objective response and better for overall response to endocrine therapy on relapse.