The American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) have revised the clinical guidelines for report HER2/neu testing by immunohistochemistry (IHC).
Patient selection: invasive breast carcinoma
Testing: validated immunohistochemical assay for HER2
Requirements for interpretation:
(1) interpretation of the invasive component of the tumor
(2) controls (batch, on-slide) show appropriate hybridization
Parameters:
(1) circumferential pattern of membrane staining
(2) intensity of staining
(3) percent of tumor cells staining
|
Circumferential Pattern |
Intensity |
Percent |
Interpretation |
|
complete |
intense |
> 10% |
3+ (positive) |
|
complete |
intense |
<= 10% |
2+ (equivocal) |
|
complete |
weak or moderate |
> 10% |
2+ (equivocal) |
|
incomplete |
weak, moderate, intense |
> 10% |
2+ (equivocal) |
|
incomplete |
faint |
> 10% |
1+ (negative) |
|
incomplete |
faint |
<= 10% |
0 (negative) |
|
none |
NA |
NA |
0 (negative) |
where:
• Faint = barely perceptible
• Complete circumferential staining and faint would be an unlikely pattern.
• Complete, weak or moderate and <= 10% would probably be 1+.
Equivocal results should have reflex testing using one of the following:
(1) in situ hybridization (ISH) on the same specimen
(2) immunohistochemistry or ISH on a new specimen (or different block)
Specialty: Hematology Oncology, Surgery, general, Obstetrics & Gynecology
ICD-10: ,
