Loss of BRCA1 leads to an increase in epidermal growth factor receptor expression in mammary epithelial cells, and epidermal growth factor receptor inhibition prevents estrogen receptor-negative cancers in BRCA1-mutant mice

Table 1 Clinicopathologic features of observed tumors in erlotinib-treated prevention cohort and controls^a

Clinicopathologic features	Erlotinib (N= 13)	Control (N= 14)	Pvalue
Median disease-free survival, days	365	256	0.0001
Number of tumors	19	31	0.0003
ER-positive tumors	14	12	n.s.
ER-negative tumors	5	19	0.0000002
EGFR^b			0.0004
0	10	3
1+	6	8
2+	0	6
3+	0	2
Mean ALDH1^b, % (±SD)	3.8% (2.8%)	9.0% (9.8%)	0.11 (n.s.)
Mean Ki-67^b, % (±SD)	21.4% (14%)	30.4% (17.7%)	0.6 (n.s.)
Mean cleaved caspase 3^b, % (±SD)	18.4% (8.6%)	10.6% (8.4%)	0.018

^aER, estrogen receptor; n.s., not significant; EGFR, epidermal growth factor receptor; ALDH1, aldehyde dehydrogenase 1; SD, standard deviation; ^bonly 16 tumors in the erlotinib-treated cohort and 19 tumors in the control cohort could be processed for EGFR, ALDH1, cleaved caspase 3 and Ki-67. A two-sided t-test was performed to analyze statistical significance.

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