1Department of Pathology, Seoul National University Bundang Hospital, Seongnam, Korea
2Department of Pathology, Seoul National University College of Medicine, Seoul, Korea
3Department of Pathology, Kangwon National University Hospital, Chuncheon, Korea
© The Korean Society of Pathologists/The Korean Society for Cytopathology
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Author contributions
Project administration: SA.
Supervision: SYP.
Writing—original draft: SA, JWW, KL, SYP.
Writing—review & editing: SYP.
Conflicts of Interest
S.Y.P. is the editor-in-chief of the Journal of Pathology and Translational Medicine and was not involved in the editorial evaluation or decision to publish this article. All remaining authors declare that they have no potential conflicts of interest.
Funding
No funding to declare.
HER2 IHC status | 2007 ASCO/CAP guidelines | 2013 ASCO/CAP guidelines | 2018 ASCO/CAP guidelines |
---|---|---|---|
Positive (3+) | Uniform intense membrane staining of >30% of invasive tumor cells | Circumferential membrane staining that is complete, intense, and in >10% of tumor cells | Circumferential membrane staining that is complete, intense, and in >10% of tumor cells |
Equivocal (2+) | Complete membrane staining that is either non-uniform or weak in intensity but with obvious circumferential distribution in at least 10% of cells | Circumferential membrane staining that is incomplete and/or weak to moderate and within >10% of the invasive tumor cells | Weak to moderate complete membrane staining observed in >10% of tumor cellsa |
Complete and circumferential membrane staining that is intense and within ≤10% of the invasive tumor cells | |||
Negative (1+) | Weak incomplete membrane staining in any proportion of tumor cells | Incomplete membrane staining that is faint or barely perceptible and within >10% of the invasive tumor cells | Incomplete membrane staining that is faint or barely perceptible and within >10% of the invasive tumor cells |
Weak, complete membrane staining in <10% of tumor cells | |||
Negative (0) | No staining | No staining observed | No staining observed |
Incomplete membrane staining that is faint or barely perceptible and within ≤10% of the invasive tumor cells | Incomplete membrane staining that is faint or barely perceptible and within ≤10% of the invasive tumor cells |
ASCO, American Society of Clinical Oncology; CAP, College of American Pathologists; HER2, human epidermal growth factor receptor 2; IHC, immunohistochemistry.
aUnusual staining patterns of HER2 by IHC can be encountered that are not covered by these definitions. As one example, some specific subtypes of breast cancers can show IHC staining that is moderate to intense but incomplete (basolateral or lateral) and can be found to be HER2 amplified. Another example is circumferential membrane staining that is intense but in ≤ 10% tumor cells. Such cases can be considered equivocal (2+).
HER2 ISH status | 2007 ASCO/CAP guidelines | 2013 ASCO/CAP guidelines | 2018 ASCO/CAP guidelines |
---|---|---|---|
ISH positive | HER2/CEP17 ratio > 2.2 | HER2/CEP17 ratio ≥ 2.0 | HER2/CEP17 ratio ≥ 2.0 and average HER2 copy number ≥ 4.0 (group 1) |
HER2/CEP17 ratio < 2.0 and average HER2 copy number ≥ 6.0 | HER2/CEP17 ratio ≥ 2.0 and average HER2 copy number < 4.0 (group 2) with concurrent IHC 3+ | ||
HER2/CEP17 ratio < 2.0 and average HER2 copy number ≥ 6.0 (group 3) with concurrent IHC 2+a | |||
HER2/CEP17 ratio < 2.0 and average HER2 copy number ≥ 6.0 (group 3) with concurrent IHC 3+ | |||
HER2/CEP17 ratio < 2.0 with average HER2 copy number ≥ 4.0 and < 6.0 (group 4) with concurrent IHC 3+ | |||
ISH equivocal | HER2/CEP17 ratio of 1.8-2.2 | HER2/CEP17 ratio < 2.0 with average HER2 copy number ≥ 4.0 and < 6.0 | (no equivocal category) |
ISH negative | HER2/CEP17 ratio of < 1.8 | HER2/CEP17 ratio < 2.0 with average HER2 copy number < 4.0 | HER2/CEP17 ratio < 2.0 with average HER2 copy number < 4.0 (group 5) |
HER2/CEP17 ratio ≥ 2.0 and average HER2 copy number < 4.0 (group 2) with concurrent IHC 2+b | |||
HER2/CEP17 ratio < 2.0 with average HER2 copy number ≥ 4.0 and < 6.0 (group 4) with concurrent IHC 2+b | |||
Groups 2, 3, and 4 with concurrent IHC 0 or 1 + |
ASCO, American Society of Clinical Oncology; CAP, College of American Pathologists; HER2, human epidermal growth factor receptor 2; ISH, in situ hybridization; CEP17, chromosome enumeration probe 17; IHC, immunohistochemistry.
aAn additional observer blinded to previous result recounts ISH. If the repeated ISH result is categorized to the same group, it is finally regarded as HER2 positive;
bAn additional observer blinded to previous result recounts ISH. If the repeated ISH result is designated to same ISH group, it is finally regarded as HER2 negative.
Year | Author | Total No. of cases | Method |
Frequency of HER2 alteration, n (%) |
||
---|---|---|---|---|---|---|
Total | + to – | – to + | ||||
2018 | De La Cruz et al. [53] | 54 | IHC/FISH | 2/54 (3.7) | 1/54 (1.9) | 1/54 (1.9) |
2018 | Ahn et al. [52] | 442 | IHC/SISH | 15/442 (3.4) | 4/442 (0.9) | 11/442 (2.5) |
2017 | Xian et al. [54] | 77 | IHC/FISH | 6/77 (7.8) | 5/77 (6.5) | 1/77 (1.3) |
2017 | Reddy et al. [55] | 140 | IHC/FISH | 8/97 (8.2) | 5/97 (5.2) | 3/97 (3.1) |
2016 | Gahlaut et al. [56] | 133 | IHC/FISH | 8/133 (6.0) | 5/133 (3.8) | 3/133 (2.3) |
2016 | Lim et al. [57] | 290 | IHC/FISH | 17/290 (5.9) | 17/290 (5.9) | 0/290 (0) |
2016 | Zhou et al. [58] | 107 | IHC/FISH | 5/107 (4.7) | 3/107 (2.8) | 2/107 (1.9) |
2015 | Jin et al. [59] | 423 | IHC/FISH | 40/423 (9.5) | 27/423 (6.4) | 13/423 (3.1) |
2013 | Yang et al. [60] | 113 | IHC | 17/113 (15.0) | 9/113 (8.0) | 8/113 (7.1) |
2013 | Cockburn et al. [61] | 133 | IHC/FISH | 16/133 (12.0) | 9/133 (6.8) | 7/133 (5.3) |
2013 | Lee et al. [62] | 120 | IHC/FISH | 11/107 (10.3) | 6/107 (5.6) | 5/107 (4.7) |
2009 | Hirata et al. [63] | 368 | IHC/FISH | 35/368 (9.5) | 22/368 (6.0) | 13/368 (3.5) |
2008 | Kasami et al. [64] | 173 | IHC/FISH | 0/173 (0) | 0/173 (0) | 0/173 (0) |
2006 | Neubauer et al. [65] | 87 | IHC | 13/87 (14.9) | 11/87 (12.6) | 2/87 (2.3) |
2003 | Faneyte et al. [66] | 50 | IHC | 3/50 (6.0) | 2/50 (4.0) | 1/50 (2.0) |
Year | Author | Total No. of cases | Method | Site |
Frequency of HER2 alteration, n (%) |
||
---|---|---|---|---|---|---|---|
Total | + to – | – to + | |||||
2019 | Woo et al. [79] | 152 | IHC/SISH | All | 12/152 (7.9) | 9/152 (5.9) | 3/152 (2.0) |
2014 | de Duenas et al. [70] | 165 | IHC/FISH | All | 5/165 (3.0) | 0/165 (0.0) | 5/165 (3.0) |
2013 | Curtit et al. [71] | 219 | IHC/FISH | All | 8/219 (3.7) | 6/219 (2.7) | 2/219 (0.9) |
2013 | Nakamura et al. [72] | 156 | IHC/FISH | All | 13/156 (8.3) | 5/156 (3.2) | 8/156 (5.1) |
2013 | Aurilio et al. [73] | 86 | IHC/FISH | Bone | 6/86 (7.0) | 2/86 (2.3) | 4/86 (4.7) |
2012 | Duchnowska et al. [74] | 119 | IHC/FISH | Brain | 17/119 (14.3) | 7/119 (5.9) | 10/119 (8.4) |
2012 | Jensen et al. [75] | 114 | IHC/FISH | All | 10/114 (8.8) | 2/114 (1.8) | 8/114 (7.0) |
2011 | Bogina et al. [76] | 136 | IHC/SISH | All | 1/136 (0.7) | 0/136 (0.0) | 1/136 (0.7) |
2011 | Chang et al. [77] | 56 | IHC/FISH | All | 7/56 (12.5) | 2/56 (3.6) | 5/56 (8.9) |
2010 | Hoefnagel et al. [78] | 233 | IHC/SISH | All | 12/233 (5.2) | 6/233 (2.6) | 6/233 (2.6) |
HER2 IHC status | 2007 ASCO/CAP guidelines | 2013 ASCO/CAP guidelines | 2018 ASCO/CAP guidelines |
---|---|---|---|
Positive (3+) | Uniform intense membrane staining of >30% of invasive tumor cells | Circumferential membrane staining that is complete, intense, and in >10% of tumor cells | Circumferential membrane staining that is complete, intense, and in >10% of tumor cells |
Equivocal (2+) | Complete membrane staining that is either non-uniform or weak in intensity but with obvious circumferential distribution in at least 10% of cells | Circumferential membrane staining that is incomplete and/or weak to moderate and within >10% of the invasive tumor cells | Weak to moderate complete membrane staining observed in >10% of tumor cells |
Complete and circumferential membrane staining that is intense and within ≤10% of the invasive tumor cells | |||
Negative (1+) | Weak incomplete membrane staining in any proportion of tumor cells | Incomplete membrane staining that is faint or barely perceptible and within >10% of the invasive tumor cells | Incomplete membrane staining that is faint or barely perceptible and within >10% of the invasive tumor cells |
Weak, complete membrane staining in <10% of tumor cells | |||
Negative (0) | No staining | No staining observed | No staining observed |
Incomplete membrane staining that is faint or barely perceptible and within ≤10% of the invasive tumor cells | Incomplete membrane staining that is faint or barely perceptible and within ≤10% of the invasive tumor cells |
HER2 ISH status | 2007 ASCO/CAP guidelines | 2013 ASCO/CAP guidelines | 2018 ASCO/CAP guidelines |
---|---|---|---|
ISH positive | HER2/CEP17 ratio > 2.2 | HER2/CEP17 ratio ≥ 2.0 | HER2/CEP17 ratio ≥ 2.0 and average HER2 copy number ≥ 4.0 (group 1) |
HER2/CEP17 ratio < 2.0 and average HER2 copy number ≥ 6.0 | HER2/CEP17 ratio ≥ 2.0 and average HER2 copy number < 4.0 (group 2) with concurrent IHC 3+ | ||
HER2/CEP17 ratio < 2.0 and average HER2 copy number ≥ 6.0 (group 3) with concurrent IHC 2+ |
|||
HER2/CEP17 ratio < 2.0 and average HER2 copy number ≥ 6.0 (group 3) with concurrent IHC 3+ | |||
HER2/CEP17 ratio < 2.0 with average HER2 copy number ≥ 4.0 and < 6.0 (group 4) with concurrent IHC 3+ | |||
ISH equivocal | HER2/CEP17 ratio of 1.8-2.2 | HER2/CEP17 ratio < 2.0 with average HER2 copy number ≥ 4.0 and < 6.0 | (no equivocal category) |
ISH negative | HER2/CEP17 ratio of < 1.8 | HER2/CEP17 ratio < 2.0 with average HER2 copy number < 4.0 | HER2/CEP17 ratio < 2.0 with average HER2 copy number < 4.0 (group 5) |
HER2/CEP17 ratio ≥ 2.0 and average HER2 copy number < 4.0 (group 2) with concurrent IHC 2+ |
|||
HER2/CEP17 ratio < 2.0 with average HER2 copy number ≥ 4.0 and < 6.0 (group 4) with concurrent IHC 2+ |
|||
Groups 2, 3, and 4 with concurrent IHC 0 or 1 + |
Suggestions |
---|
The pathologist should scan entire HER2 ISH slide before counting. |
Review of HER2 IHC slide is helpful to find areas with potential HER2 amplification |
From this point of view, CISH or SISH has an advantage to evaluate HER2 heterogeneity, because it can be easily matched with HER2 IHC slide under light microscope. |
If there is a subpopulation of tumor cells with HER2 amplification comprising > 10% of tumor cells on the slide, a separate counting should be performed within the subpopulation. |
The HER2/CEP17 ratios or HER2 gene copy number should be calculated for both amplified and non-amplified areas separately. |
If possible, it is recommended that in situ hybridization report includes proportion of amplified cells within a tumor. |
Year | Author | Total No. of cases | Method | Frequency of HER2 alteration, n (%) |
||
---|---|---|---|---|---|---|
Total | + to – | – to + | ||||
2018 | De La Cruz et al. [53] | 54 | IHC/FISH | 2/54 (3.7) | 1/54 (1.9) | 1/54 (1.9) |
2018 | Ahn et al. [52] | 442 | IHC/SISH | 15/442 (3.4) | 4/442 (0.9) | 11/442 (2.5) |
2017 | Xian et al. [54] | 77 | IHC/FISH | 6/77 (7.8) | 5/77 (6.5) | 1/77 (1.3) |
2017 | Reddy et al. [55] | 140 | IHC/FISH | 8/97 (8.2) | 5/97 (5.2) | 3/97 (3.1) |
2016 | Gahlaut et al. [56] | 133 | IHC/FISH | 8/133 (6.0) | 5/133 (3.8) | 3/133 (2.3) |
2016 | Lim et al. [57] | 290 | IHC/FISH | 17/290 (5.9) | 17/290 (5.9) | 0/290 (0) |
2016 | Zhou et al. [58] | 107 | IHC/FISH | 5/107 (4.7) | 3/107 (2.8) | 2/107 (1.9) |
2015 | Jin et al. [59] | 423 | IHC/FISH | 40/423 (9.5) | 27/423 (6.4) | 13/423 (3.1) |
2013 | Yang et al. [60] | 113 | IHC | 17/113 (15.0) | 9/113 (8.0) | 8/113 (7.1) |
2013 | Cockburn et al. [61] | 133 | IHC/FISH | 16/133 (12.0) | 9/133 (6.8) | 7/133 (5.3) |
2013 | Lee et al. [62] | 120 | IHC/FISH | 11/107 (10.3) | 6/107 (5.6) | 5/107 (4.7) |
2009 | Hirata et al. [63] | 368 | IHC/FISH | 35/368 (9.5) | 22/368 (6.0) | 13/368 (3.5) |
2008 | Kasami et al. [64] | 173 | IHC/FISH | 0/173 (0) | 0/173 (0) | 0/173 (0) |
2006 | Neubauer et al. [65] | 87 | IHC | 13/87 (14.9) | 11/87 (12.6) | 2/87 (2.3) |
2003 | Faneyte et al. [66] | 50 | IHC | 3/50 (6.0) | 2/50 (4.0) | 1/50 (2.0) |
Year | Author | Total No. of cases | Method | Site | Frequency of HER2 alteration, n (%) |
||
---|---|---|---|---|---|---|---|
Total | + to – | – to + | |||||
2019 | Woo et al. [79] | 152 | IHC/SISH | All | 12/152 (7.9) | 9/152 (5.9) | 3/152 (2.0) |
2014 | de Duenas et al. [70] | 165 | IHC/FISH | All | 5/165 (3.0) | 0/165 (0.0) | 5/165 (3.0) |
2013 | Curtit et al. [71] | 219 | IHC/FISH | All | 8/219 (3.7) | 6/219 (2.7) | 2/219 (0.9) |
2013 | Nakamura et al. [72] | 156 | IHC/FISH | All | 13/156 (8.3) | 5/156 (3.2) | 8/156 (5.1) |
2013 | Aurilio et al. [73] | 86 | IHC/FISH | Bone | 6/86 (7.0) | 2/86 (2.3) | 4/86 (4.7) |
2012 | Duchnowska et al. [74] | 119 | IHC/FISH | Brain | 17/119 (14.3) | 7/119 (5.9) | 10/119 (8.4) |
2012 | Jensen et al. [75] | 114 | IHC/FISH | All | 10/114 (8.8) | 2/114 (1.8) | 8/114 (7.0) |
2011 | Bogina et al. [76] | 136 | IHC/SISH | All | 1/136 (0.7) | 0/136 (0.0) | 1/136 (0.7) |
2011 | Chang et al. [77] | 56 | IHC/FISH | All | 7/56 (12.5) | 2/56 (3.6) | 5/56 (8.9) |
2010 | Hoefnagel et al. [78] | 233 | IHC/SISH | All | 12/233 (5.2) | 6/233 (2.6) | 6/233 (2.6) |
ASCO, American Society of Clinical Oncology; CAP, College of American Pathologists; HER2, human epidermal growth factor receptor 2; IHC, immunohistochemistry. Unusual staining patterns of HER2 by IHC can be encountered that are not covered by these definitions. As one example, some specific subtypes of breast cancers can show IHC staining that is moderate to intense but incomplete (basolateral or lateral) and can be found to be
ASCO, American Society of Clinical Oncology; CAP, College of American Pathologists; HER2, human epidermal growth factor receptor 2; ISH, in situ hybridization; CEP17, chromosome enumeration probe 17; IHC, immunohistochemistry. An additional observer blinded to previous result recounts ISH. If the repeated ISH result is categorized to the same group, it is finally regarded as HER2 positive; An additional observer blinded to previous result recounts ISH. If the repeated ISH result is designated to same ISH group, it is finally regarded as HER2 negative.
HER2, human epidermal growth factor receptor 2; ISH, in situ hybridization; IHC, immunohistochemistry; CISH, chromogenic in situ hybridization; SISH, silver in situ hybridization; CEP17, chromosome enumeration probe 17.
HER2, human epidermal growth factor receptor 2; IHC, immunohistochemistry; FISH, fluorescence in situ hybridization; SISH, silver in situ hybridization.
HER2, human epidermal growth factor receptor 2; IHC, immunohistochemistry; SISH, silver in situ hybridization; FISH, fluorescence in situ hybridization.