Background: The assessment of HER2 status plays a key role in the treatment decision making process of early breast cancer (BC).HER2 status is routinely assessed by immunohistochemistry and/or in situ hybridization (ISH), according to ASCO/CAP 2018 guidelines. The dichotomous definition of HER2+ versus HER2- disease does not reflect the spectrum of variable levels of HER2 protein expression. We have analyzed the clinical outcomes of a cohort of BC patients treated with neoadjuvant chemotherapy (NACT) according to HER2 score. Patients and methods: We performed a retrospective analysis of 483 women with early BC treated with NACT from March 2002 to November 2018 at Modena Cancer Center. Clinical and pathological characteristics of patients and disease were collected and compared to HER2 score by Pearson’s chi square test. The impact of HER2 status on pathological complete response (pCR) was set according to logistic regression model. Results: According to HER2 score, patients were divided in 5 groups: 79 (16,3%) of them in HER2 score0 group, 153 (31,7%) in HER2 score1+, 53 (11%) HER2 score2+/ ISH-, 43 (9%) score2+/ISH+ and 155 (32%) score3+. Of note, 59% of women had hormone receptor positive BC. Overall, the HER2 status significant correlated to histotype (p=0,003), grading (p=0,026) and pCR (p=0,0001). The pCR was achieved in 132 (27%) patients: 46 (9,5%) in HER2 score0/1+ group, 9 (1,9%) in HER2 score2+/ISH-, 8 (1,7%) in HER2 score2+/ISH+ and 69 (14,3%) in HER2 score3+. The pCR rate was not statistically different when both HER2 score0/1+ and HER2 score2+/ISHgroups were compared to HER2 score2+/ISH+ one. Considering HER2+ BCs, the pCR rate was significantly higher in HER2 score3+ compared to HER2 score2+/ ISH+ (p=0,002). No statistically significant differences in terms of RFS and OS inter-subgroups were observed. Conclusions: The HER2 protein expression levels better correlated to pCR compare to HER2 gene amplification. In particular, the lack of difference in pCR rate between HER2 score2+/ISH+ and HER2 score2+/ISH– groups may suggests a paradigm shift in the current classification of HER2 status, consistently with emerging data on “HER2 low” BC landscape.
PROGNOSIS AND RESPONSE TO NEOADJUVANT CHEMOTHERAPY ACCORDING TO HER2 EXPRESSION IN EARLY BREAST CANCER: a retrospective single institution analysis / D'Onofrio, R.; Omarini, C.; Barbolini, M.; Nasso, C.; Isca, C.; Dominici, M.; Piacentini, F.. - (2020). (Intervento presentato al convegno XXII CONGRESSO NAZIONALE ASSOCIAZIONE ITALIANA ONCOLOGIA MEDICA tenutosi a ROMA nel 30.10.2020-01.11.2020).
PROGNOSIS AND RESPONSE TO NEOADJUVANT CHEMOTHERAPY ACCORDING TO HER2 EXPRESSION IN EARLY BREAST CANCER: a retrospective single institution analysis
D'Onofrio R.;Omarini C.;Barbolini M.;Nasso C.;Isca C.;Dominici M.;Piacentini F.
2020
Abstract
Background: The assessment of HER2 status plays a key role in the treatment decision making process of early breast cancer (BC).HER2 status is routinely assessed by immunohistochemistry and/or in situ hybridization (ISH), according to ASCO/CAP 2018 guidelines. The dichotomous definition of HER2+ versus HER2- disease does not reflect the spectrum of variable levels of HER2 protein expression. We have analyzed the clinical outcomes of a cohort of BC patients treated with neoadjuvant chemotherapy (NACT) according to HER2 score. Patients and methods: We performed a retrospective analysis of 483 women with early BC treated with NACT from March 2002 to November 2018 at Modena Cancer Center. Clinical and pathological characteristics of patients and disease were collected and compared to HER2 score by Pearson’s chi square test. The impact of HER2 status on pathological complete response (pCR) was set according to logistic regression model. Results: According to HER2 score, patients were divided in 5 groups: 79 (16,3%) of them in HER2 score0 group, 153 (31,7%) in HER2 score1+, 53 (11%) HER2 score2+/ ISH-, 43 (9%) score2+/ISH+ and 155 (32%) score3+. Of note, 59% of women had hormone receptor positive BC. Overall, the HER2 status significant correlated to histotype (p=0,003), grading (p=0,026) and pCR (p=0,0001). The pCR was achieved in 132 (27%) patients: 46 (9,5%) in HER2 score0/1+ group, 9 (1,9%) in HER2 score2+/ISH-, 8 (1,7%) in HER2 score2+/ISH+ and 69 (14,3%) in HER2 score3+. The pCR rate was not statistically different when both HER2 score0/1+ and HER2 score2+/ISHgroups were compared to HER2 score2+/ISH+ one. Considering HER2+ BCs, the pCR rate was significantly higher in HER2 score3+ compared to HER2 score2+/ ISH+ (p=0,002). No statistically significant differences in terms of RFS and OS inter-subgroups were observed. Conclusions: The HER2 protein expression levels better correlated to pCR compare to HER2 gene amplification. In particular, the lack of difference in pCR rate between HER2 score2+/ISH+ and HER2 score2+/ISH– groups may suggests a paradigm shift in the current classification of HER2 status, consistently with emerging data on “HER2 low” BC landscape.
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