Electronic ISSN 2287-0237

VOLUME

REPRODUCIBILITY IN THE ASSESSMENT OF HER2 DISH IN BREAST CANCER

SEPTEMBER 2015 - VOL.10 | ORIGINAL ARTICLE
OBJECTIVE

HER2 gene status is an important biological marker that determines both the prognosis and response to Trastuzumab in patients with breast cancers. Although FISH assay has long been used to determine the HER2 gene copy number, DISH is gaining popularity since it can be assessed with a conventional microscope. The DISH test relies on an individual inspection however, so inter-observer variation may be an issue.

MATERIALS AND METHODS

In the current study, reproducibility in the assessment of HER2 DISH test was evaluated in 69 breast cancer samples with HER2 IHC score 2+ and 3+. Two independent investigators evaluated the digitallycaptured images of DISH, without the knowledge of HER2 IHC status.

RESULTS

The HER2/CEP17 ratio obtained from both observers were highly correlated (Rho = 0.883, p < 0.001). Based on the ASCO 2013 guideline, agreement of both investigators for HER2 gene diagnosis was 92.75 % (ĸ = 0.848). The HER2/CEP17 ratio of the discordant cases ranged from 1.6 (non-amplifi ed HER2) to 2.6 (low level of HER2 gene amplification).

CONCLUSION

It is concluded that the DISH method produces good reproducibility between independent observers, and the result also implies that the HER2 gene copy number is fairly homogenous across an individual breast cancer sample.

Keywords

breast cancer, HER2, DISH, FISH, reproducibility

MEDIA
Table 1: Interpretation Guideline of HER2 ISH (ASCO/CAP 2013).
Table 2: Disagreed Cases.
Table 3: Correlation of HER2 IHC score and DISH status of all concordance cases.
Figure 1: Invasive breast cancer with HER2 amplified by DISH method.
Figure 2: Invasive breast cancer with HER2 non-amplified by DISH method.
Figure 3
Figure 4: HER2 DISH results assessed independently by two investigators (disagreed cases marked with red arrow heads).
Figure 5: Invasive breast cancer with HER2 amplified by DISH method.
Figure 6: Invasive breast cancer with HER2 amplified by DISH method.
Table 4: Comparison between DISH and FISH methods for HER2 gene assessment.
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