Table 2.

HER2 Gene Amplification and Hormone Receptor Status Following Trastuzumab Containing Neoadjuvant Chemotherapy in Patients with Enough Residual Disease Identified at the Time of Surgery to Reassess HER2 Status

Patient Number	HER2 FISH Ratio Pre-Treatment	HER2 FISH Ratio Post-Treatment	ER* Pre-Treatment	ER Post-Treatment
1	3.17	1.96	NEG	NEG
2	6.06	4.78	POS	POS
3	POS (Aneuploid)†	POS (Aneuploid)†	POS	POS
4	7.19	6.22	NEG	POS
5	3.70	1.94	NEG	NEG
6	2.88	1.24	POS	N/A
7	5.06	5.02	POS	POS
8	5.26	5.26	POS	POS
9	5.48	4.46	POS	POS
10	5.41	1.32	NEG	POS
11	5.04	1.26	NEG	N/A
12	13.79	6.23	POS	POS
13	4.70	4.25	NEG	POS
14	11.63	9.63	POS	POS
15	2.39	2.42	POS	POS
16	6.22	1.23	NEG	NEG
17	4.26	4.22	NEG	NEG
18	11.65	1.28	POS	N/A
19	8.74	6.56	POS	POS
20	6.52	4.26	POS	N/A
21	3.87	3.56	NEG	NEG
22	2.56	2.61	NEG	POS
23	6.82	7.12	POS	POS
24	2.96	1.29	NEG	NEG
25	2.78	2.38	POS	N/A

^*ER status was determined by immunohistochemical analysis. Nuclear staining ≥ was considered positive.

^†Due to marked aneuploidy of tumor cells and clustering of signals, HER2/neu and CEP17 signals could not be accurately counted however there was at least a 2-fold increase in the number of signals for HER2/neu compared to CEP17.

Abbreviations: ER, estrogen receptor; PR, progesterone receptor; POS, positive; NEG, negative; N/A = not enough residual tumor available to assess.

Patients who lost HER2 amplification are identified in bold.