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
452P - The relationship between BCG immunotherapy and oxidative stress parameters in patients with non-muscle invasive bladder cancer
Presenter: Mukul Singh
Session: Poster Display
Resources:
Abstract
453P - Palonosetron plus megestrol acetate verses palonosetron plus dexamethasone in preventing moderately emetogenic chemotherapy-induced nausea and vomiting: A randomized, multicenter, crossover, phase II trial
Presenter: Qiaoqi Li
Session: Poster Display
Resources:
Abstract
454P - A multicenter randomized open-label phase II study investigating optimal antiemetic therapy for patients with advanced/recurrent gastric cancer treated with trastuzumab deruxtecan (T-DXd): EN-hance study
Presenter: Akira Ooki
Session: Poster Display
Resources:
Abstract
455P - Assessing model-predicted neurokinin-1 (NK1) receptor occupancy (RO) of netupitant to support efficacy over an extended time period
Presenter: Matti Aapro
Session: Poster Display
Resources:
Abstract
456P - Oxycodone/naloxone in moderate-to-severe cancer pain: A phase III study in China
Presenter: Ping Lu
Session: Poster Display
Resources:
Abstract
457P - Anticoagulation for terminal cancer patients with cancer associated venous thromboembolism
Presenter: Sang Bo Oh
Session: Poster Display
Resources:
Abstract
458P - Association between TSPAN15 and SLC44A2 genetic polymorphisms and venous thromboembolism in cancer patients
Presenter: Alshimaa Al Hanafy
Session: Poster Display
Resources:
Abstract
459P - Association between national health screening program and undertreatment of dyslipidemia in cancer survivors: A cross-sectional study
Presenter: Sujeong Shin
Session: Poster Display
Resources:
Abstract
460P - Group to grow: A systematic review of group-based interventions for post-traumatic growth on cancer patients
Presenter: Dyta William
Session: Poster Display
Resources:
Abstract
461P - A randomized controlled trial of yoga in locally advanced non-small cell lung cancer patients receiving chemoradiotherapy
Presenter: Indranil Khan
Session: Poster Display
Resources:
Abstract