Table 3. Genetic aberration of breast cancer–related oncogenes and regions detected by MIP microarray.
| Total | HR+/HER2+ | HR+/HER2- | HR-/HER2+ | HR-/HER2- | P value | |
|---|---|---|---|---|---|---|
| n (%) | n (%) | n (%) | n (%) | n (%) | ||
| Patients | 42 (100) | 14 (33) | 15 (36) | 6 (14) | 7 (17) | |
| HER2 | ||||||
| Amplification by MIP | 19 (45) | 13 (93)a | 1 (7)b | 5 (83)c | 0 | <0.001 |
| CLP at 17q12 | 8 (19) | 6 (43) | 0 | 2 (33) | 0 | <0.01 |
| 17p11.2-q11.2 | ||||||
| Amplification by MIP | 14 (33) | 8 (57) | 1 (7)b | 5 (83)c | 0 | <0.001 |
| 17p11.2 amplification by MIP | 5 (12) | 4 (29) | 0 | 1 (17) | 0 | 0.06 |
| 17q11.2 amplification by MIP | 13 (31) | 7 (50) | 1 (7)b | 5 (83) | 0 | <0.001 |
| Co-segmental amplification of 17q12 and 17p11.2-q11.2 by MIP | 14 (33) | 8 (57) | 1 (7)b | 5 (83) | 0 | <0.001 |
| FGFR1 | ||||||
| Amplification by MIP | 9 (21) | 3 (21) | 3 (20) | 1 (17) | 2 (29) | 1.0 |
aOne case showed HER2 genetic heterogeneity. The immunohistochemistry results were equivocal; fluorescence in situ hybridization results were positive in the tumor area with HER2–amplified tumor cells; the overall HER2 gene status in tumors was negative by MIP microarray.
bOne case was equivocal for both HER2 overexpression (2+) and HER2 amplification by fluorescence in situ hybridization (HER2 copy number/cell, 4.22; HER2/CEP17 ratio, 1.1). MIP microarray results were positive for HER2 amplification (4 copies) and 17q11.2 amplification.
dOne case was equivocal for HER2 overexpression (2+) and positive for HER2 amplification by fluorescence in situ hybridization (HER2 copy number/cell, 4.65; HER2/CEP17 ratio, 2.12). MIP microarray results were negative for HER2 amplification (2.33 copies) and negative for 17p11.2-q11.2 amplification.
Abbreviations: CLP, chromothripsis-like pattern; FGFR1, fibroblast growth factor receptor 1; HER2, human epidermal growth factor receptor 2; HER2+, HER2–positive according to fluorescence in situ hybridization; HER2-, HER2–negative and equivocal results according to immunohistochemistry and/or fluorescence in situ hybridization; HR, hormone receptor; HR+, HR–positive according to immunohistochemistry; HR-, HR–negative according to immunohistochemistry; MIP, molecular inversion probe.