Abstract 25P
Background
With the advent of novel antibody-drug conjugate (ADC), an emerging subgroup of human epidermal growth factor receptor 2 (HER2)-low breast cancer has been recognized which may take advantage from the anti-tumor activity. We took advantage of Taiwan Cancer Registry (TCR) to evaluate the clinical presentations and prognostication for HER2-low breast cancer.
Methods
HER2-low breast cancers were defined operationally with HER2 immunohistochemistry (IHC) 1+ or 2+ with a negative fluorescence in situ hybridization (FISH) while HER2-zero defined with an IHC score 0. Breast cancer index cases (n=189465) from TCR between 2007 and 2017 were reduced to 133546 sides of breast cancer per subject. Clinical features such as IHC test, stage, grade and outcomes such as relapse-free and overall survival were compared between HER2-low and HER2-zero.
Results
The safety analysis group comprised 37195 HER2-negative breast cancers, including 14288 IHC 1+, 10486 FISH-negative, 8907 IHC 0 and 3323 IHC 2+/FISH-undetermined cases. Among HER2-negative breast cancers, the proportion of HER2-low and HER2-zero was 68.9% and 31.1%, respectively, after excluding HER2 ambiguity. Overall survival was 95.7% versus 95.9% for HER2-low and HER2-zero breast cancers, which was 94.1% and 94.7% for relapse-free survival. The distributions of pathological stages from 0 to IV were 6.7%, 41.5%, 38.5%, 13.1% and 0.3% for HER2-low and were 8.5%, 42.8%, 37.5%, 11% and 0.4% for HER2-zero breast cancers. Regarding estrogen receptor (ER) and progesterone receptor (PR) status, 87.6% and 80.9% of the HER2-low cases were ER+ and PR+ while 81.9% and 74.8% of the HER2-zero patients were ER+ and PR+. High or poorly differentiated grade was reported from 23.4% of HER2-low and 25.5% of HER2-zero breast cancers. The diagnosed age was 54 versus 54.3 between HER2-low and HER2-zero breast cancers (P=0.02).
Conclusions
HER2-low status is not a prognostic marker for Taiwanese breast cancers while a slightly younger age of disease onset, less than half diagnosed with stage 0 and I, more ER and PR positivity and fewer grade III disease were observed for HER2-low phenotype compared with HER2-zero counterpart. These trivial differences distinguished HER2-low from HER2-zero spectrum among Taiwanese HER2-negative breast cancers.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
LMT.
Funding
Melissa Lee Cancer Foundation.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
497P - Sintilimab in combination with anlotinib in advanced NSCLC treated with first-line PD-1 antibodies: An open, single-arm, phase II trial
Presenter: Ying Jin
Session: Poster Display
Resources:
Abstract
498P - Frailty-adjusted life expectancy and survival in older lung cancer patients: A large-scale electronic health-record based study
Presenter: Thao Tu
Session: Poster Display
Resources:
Abstract
499P - Long-term survival and treatment (tx) patterns after first-line (1L) osimertinib in patients (pts) with epidermal growth factor receptor (EGFR) mutation-positive (m) advanced non-small cell lung cancer (NSCLC): Japanese cohort of a global real-world (rw) observational study
Presenter: Daichi Fujimoto
Session: Poster Display
Resources:
Abstract
500P - The effectiveness and safety of durvalumab after chemoradiotherapy for locoregional recurrence of completely resected non-small cell lung cancer: Real-world, multicenter, observational study (NEJ056)
Presenter: Hidehito Horinouchi
Session: Poster Display
Resources:
Abstract
501P - One-year survival outcomes of unresectable stage III non-small cell lung cancer patients who underwent PD-1 inhibitor plus chemo as induction therapy
Presenter: Xin Wang
Session: Poster Display
Resources:
Abstract
502P - Impact of sarcopenia on the outcome of patients with locally advanced non-small cell lung cancer treated with chemoradiotherapy followed by durvalumab
Presenter: Kentaro Tamura
Session: Poster Display
Resources:
Abstract
503P - Clinical outcomes by infusion timing of immune checkpoint inhibitors in patients with locally advanced NSCLC
Presenter: TSUYOSHI HIRATA
Session: Poster Display
Resources:
Abstract
504P - Real-world outcomes with induction systemic therapy for stage III in eligible for upfront local therapy: Pre vs post immunotherapy era in a tertiary referral centre
Presenter: Praveen Kumar Marimuthu
Session: Poster Display
Resources:
Abstract
505P - Neoadjuvant PD-1 inhibitor (tislelizumab) plus platinum–etoposide in patients with limited-stage small cell lung cancer: A phase II trial
Presenter: Junjie Hu
Session: Poster Display
Resources:
Abstract
506P - Intrathoracic progression is still the most dominant failure pattern after first-line chemo-immunotherapy in extensive-stage small-cell lung cancer: Implications for thoracic radiotherapy
Presenter: Byoung Hyuck Kim
Session: Poster Display
Resources:
Abstract