Abstract
BackgroundMolecular classification of breast cancer is an important prognostic factor. The distribution of molecular subtypes of breast cancer and their prognostic value has not been well documented in Asians.MethodsA total of 2,791 breast cancer patients recruited for a population-based cohort study were evaluated for molecular subtypes of breast cancer by immunohistochemical assays. Data on clinicopathological characteristics were confirmed by centralized pathology review. The average follow-up of the patients was 53.4 months. Overall and disease-free survival by molecular subtypes of breast cancer were evaluated.ResultsThe prevalence of the luminal A, luminal B, human epidermal growth factor receptor 2 (HER2), and triple-negative subtypes were 48.6%, 16.7%, 13.7%, and 12.9%, respectively. The luminal A subtype was more likely to be diagnosed in older women (P = 0.03) and had a stronger correlation with favorable clinicopathological factors (smaller tumor size, lower histologic grade, and earlier TNM stage) than the triple-negative or HER2 subtypes. Women with triple-negative breast cancer had a higher frequency of family history of breast cancer than women with other subtypes (P = 0.048). The 5-year overall/disease-free survival percentages for the luminal A, luminal B, HER2, and triple-negative subtypes were 92.9%/88.6%, 88.6%/85.1%, 83.2%/79.1%, and 80.7%/76.0%, respectively. A similar pattern was observed in multivariate analyses. Immunotherapy was associated with improved overall and disease-free survival for luminal A breast cancer, but reduced disease-free survival (HR = 2.21, 95% CI, 1.09-4.48) for the HER2 subtype of breast cancer.ConclusionsThe triple-negative and HER2 subtypes were associated with poorer outcomes compared with the luminal A subtype among these Chinese women. The HER2 subtype was more prevalent in this Chinese population compared with Western populations, suggesting the importance of standardized HER2 detection and anti-HER2 therapy to potentially benefit a high proportion of breast cancer patients in China.
Highlights
Molecular classification of breast cancer is an important prognostic factor
The variables significantly related to 5-year survival were: age at diagnosis, education, income, TNM stage, histologic grade and type, estrogen receptor-alpha (ERa), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) status, and use of adjuvant therapy
We found that use of immunotherapy was associated with improved overall and disease-free survival among women with the luminal A subtype but with reduced disease-free survival among women with the HER2 subtype, suggesting that choosing the proper immunotherapeutic method should be based on the molecular characteristics of the tumor
Summary
Molecular classification of breast cancer is an important prognostic factor. The distribution of molecular subtypes of breast cancer and their prognostic value has not been well documented in Asians. One study has suggested that the HER2 subtype is more common in Asian populations and that the distribution of breast cancer subtypes among Asian women may vary by ethnicity (i.e., Chinese, Japanese, etc.) [9]. A few studies have evaluated the molecular subtypes of breast cancer in Chinese women [10,11,12,13,14]. Most of those studies have had a relatively small sample size and applied different criteria to define positivity. The distribution of molecular subtypes of breast cancer and their correlation with breast cancer outcomes were evaluated
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