Clinical Pathological Practicing Analysis Of HER2 FISH Detection In Breast Cancer By2018 ASCO/CAP Updated Guidelines

Objective:To evaluate the effect of the 2018 ASCO/CAP guidelines on the HER2 FISH results of primary invasive breast cancers.And to analyze the clinicopathological characteristics of different HER2 states in invasive breast cancer.Methods:1.1795 cases of invasive breast cancer were enrolled in this study between January 2015 and October 2019 at pathological diagnosis center of Chongqing Medical University.HER2 FISH of all cases results were interpreted according to 2013 and 2018 guidelines respectively.And we compared the changes in the HER2 results after the interpretation of the new and old guidelines respectively.2.We compared the clinicopathological characteristics of the HER2 classic positive group and the HER2 classic negative group in invasive breast cancer,and analyzed the clinicopathological characteristics of the rare group of HER2 FISH.Results: 1.A total of 1795 patients with primary invasive breast cancer were enrolled in this study.After applying the 2013 guidelines to evaluate the results of HER2 FISH,40.78% were HER2 positive,4.23%were HER2 equivocal,and 54.99% were HER2 negative.Under the 2018 guidelines,40.56% were HER2 positive and 59.44% were HER2 negative.4.46% cases changed their HER2 results between the two guidelines(P<0.001).The changes in the HER2 results were that some of the previous positive cases and all suspicious cases were re-interpreted as negative.2.In invasive breast cancer,the HER2 classic positive group and the HER2 classic negative group have statistical differences in the age of onset,tumor histological grade,expression of hormone receptor and Ki67 proliferation index.Compared with the HER2 classic negative group,the HER2 classic positive group has the characteristics including younger age of onset,higher tumor histological grade,lower expression rate of hormone receptors,and higher Ki67 proliferation index.3.The HER2 FISH 4 group is a rare group.This group was judged as suspicious in the 2013 guidelines,and all the cases in this group were re-interpreted as negative results in the 2018 guidelines.The multiple clinicopathological characteristics of this group of cases are statistically different to those in the HER2 classic positive group.There was no significant difference in the clinicopathological characteristics between this group and the HER2 classic-negative group.4.The HER2 FISH group 2 and group 3 are also rare groups.Few cases were included in this study.All cases in group 2 were re-interpreted from previous positive results to negative results,and none of the patients in this group received HER2 targeted therapy,so it is almost impossible to know the status of patient after HER2 targeted therapy.This study listed the relevant clinicopathological characteristics of the two groups.Conclusions: 1.The application of 2018 guidelines decreased the rate of HER2 positive results and eliminate the diagnosis of HER2 FISH equivocal results in invasive breast cancers resulting in the definite judgement in HER2 FISH results,which provides clinicians and pathologists with more clear diagnosis ideas.2.In invasive breast cancers,HER2 is usually one of the prognostic factors for patients.HER2-positive breast cancer patients are usually associated with worse clinicopathological features,such as higher tumor histological grade,lower expression rate of hormone receptors,and higher Ki67 proliferation index,and these clinicopathological characteristics are also factors related to the prognosis of breast cancers.Therefore,HER2-positive breast cancer has a worse prognosis.3.This study found that the clinicopathological characteristics of the HER2 FISH 4 group and of the HER2 classic positive group were statistically different,but there was no statistical difference with the HER2 classic negative group,indicating that the clinicopathological characteristics of the HER2 FISH 4 group were more inclined to the HER2 classic negative group,which also confirms that the change in the new guidelines reinterpreting the HER2 FISH 4 group as negative results to be more accurate and instructive.