Treatment and pathologic considerations
All of the patients received a complete course of neoadjuvant
chemotherapy consisting of taxane, anthracycline, or both, and
trastuzumab was given to patients with HER2+ breast cancer. After
neoadjuvant chemotherapy, all patients underwent breast conserving
surgery, axillary staging surgery with sentinel lymph node biopsy (SLNB)
and/or axillary lymph node dissection (ALND), and irradiation therapy.
When performing lumpectomy (BCS) after NAC, we remove the tumor with
approximate 1 cm grossly negative margin. After completion of this
lumpectomy, margins were evaluated by shaving the walls of the
lumpectomy cavity, which was described previously by Chen K et
al14. An
intraoperatively frozen section analysis was performed to evaluate
whether the tumor was involved in the cavity margins, and if the tumor
was involved in the cavity margins, then additional excision of the
involved margins for approximate 1cm width (not the whole circle of the
cavity wall) was performed until free margins were obtained, AH but no
tumor at the margin was also defined as a negative margin. Postoperative
paraffin-embedded hematoxylin and eosin (H&E) staining was used to
confirm the pathology diagnosis in the cavity margin specimens. AH at
the margin was reviewed by two dedicated pathologists to verify the
diagnosis in the tumor-free margin specimens. Additional adjuvant
chemotherapy, targeted therapy (trastuzumab), and endocrine therapy were
given when necessary according to the NCCN guidelines. There are two
types of atypical hyperplasia, atypical ductal hyperplasia(ADH) and
atypical lobular hyperplasia(ALH), which are based on their microscopic
appearance, and ADH and ALH occur with equal frequency and confer a
similar risk of breast
cancer7. Therefore, in
this study, we analyzed these two pathological features together as
“atypical hyperplasia” (AH). ADH and ALH were diagnosed according to
the criteria established by Page et
al15. In atypical
ductal hyperplasia, the involved ducts are filled and distended by
monotonous epithelial cells forming architecturally complex patterns,
including cribriform-like secondary lumens or micropapillary formations.
Atypical lobular hyperplasia is characterized by expanded lobular acini
filled with small, monotonous, round or polygonal cells, including a
lack of cohesion and a loss of acinar
lumens7.