Criteria of Vance et al for Genetic Heterogeneity (GH) in HER2 FISH Testing in Breast Cancer

 

Patient selection: infiltrating breast cancer

 

Testing: HER2 by FISH

 

Parameters:

(1) percent of infiltrating tumor cells with a HER2 to CEP17 ratio > 2.2

(2) percent of infiltrating tumor cells with HER2 signals => 6 (with probe for HER2 only)

percent of infiltrating cancer cells with HER2 to CEP17 Ratio > 2.2	Interpretation
<= 5%	HER2 not amplified
5 to 49.9%	genetic heterogeneity
>= 50%	HER2 amplified

 

 

percent infiltrating cancer cells with HER2 signals > 6	Interpretation
<= 5%	HER2 not amplified
5 to 49.9%	genetic heterogeneity
>= 50%	HER2 amplified

 

When reporting GH describe:

(1) whether the cells showing amplification are scattered or in a cluster

(2) the area of any cluster

(3) whether a cluster shows a histology distinctive from the rest of the cancer

 

NOTE: In 2013 the cutoffs for positive HER2 testing by FISH were modified.to either a ratio >= 2 OR HER2 signals >= 6. The criteria for GH (based on when the tumor is HER2 amplified) would need to be adjusted accordingly.