How would you manage adjuvant therapy for a premenopausal female with a T1cN1mi breast IDC that is HR+ HER2 positive on biopsy, but HR+ HER2 negative on lumpectomy surgical specimen?
<40y/o female w/ initial biopsy showing G3 IDC with 80% ER+, 90% PR+, and HER2 positive (IHC 2+; 1.6 HER2/CEP17 ratio and 6.3 HER2 copies/nucleus.)
Lumpectomy specimen showed G2 IDC measuring 2.0 cm with LVI and 1/2 sentinel LNs positive for micro-mets (0.26 mm). HER2 IHC 1+; 1.4 HER2/CEP17 ratio and 6.1 HER2 copies/nucleus. Final FISH report called her tumor HER2 negative.
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How would you manage adjuvant chemotherapy for a premenopausal female with T1cN1mi IDC that is HR+ HER2 positive on biopsy, but HR+ HER2 negative on lumpectomy surgical specimen?
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2 Answers
Mednet MemberInvited Expert
Medical Oncology · University of Wisconsin School of Medicine and Public Health
Answered on
Overall, I agree with Dr. @Dr. First Last's response regarding treating this as a heterogenous tumor, but I would probably lean towards 4 cycles of TC (docetaxel/cyclophosphamide) for the HR+/HER2 neg component and then add 1 year of trastuzumab. This would avoid the risks of anthracyclines and pert...
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Mednet MemberInvited Expert
Medical Oncology · The University of Texas MD Anderson Cancer Center
Answered on
HER2 testing is overall borderline and would be considered positive by the biopsy and negative by the surgical specimen when both IHC and FISH results are taken into consideration. HER2 FISH testing result falls into Group 3 and is similar in both specimens. In Group 3, HER2 is currently deemed posi...
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