Clinical Significance of Subtype Classification in Metastatic Lymph Nodes of Breast Cancer Patients Undergoing Neoadjuvant Chemotherapy

Clinical Significance of ABCG2/BCRP Quantified by Fluorescent Nanoparticles in Breast Cancer Patients Undergoing Neoadjuvant Chemotherapy

Breast cancer resistance protein (BCRP), also known as ATP-binding cassette transporter G2 (ABCG2), is associated with chemotherapy resistance. BCRP is also implicated in breast cancer stem cells, and is reported as a poor prognostic factor. However, the relationship of BCRP levels in breast cancer tissues with chemotherapy resistance and prognosis has not been clarified. We aimed to evaluate the correlation between BCRP expression and prognosis in breast cancer using immunohistochemistry with fluorescent phosphor-integrated dots (IHC-PIDs). A total of 37 breast cancer patients with residual cancer in the primary tumor and axillary lymph nodes were evaluated. BCRP levels in breast cancer tissue and metastatic lymph nodes were quantitatively detected after neoadjuvant chemotherapy (NAC). Among these 37 patients, 24 had corresponding core needle biopsies obtained before NAC. Biomarker assay with IHC-PIDs showed high accuracy for the quantitative assessment of BCRP with low expression. High BCRP expression in the primary tumor and metastatic lymph nodes after preoperative chemotherapy was associated with worse overall survival. In conclusion, high BCRP levels may be associated with poor prognosis in patients with breast cancer, having residual tumors within the primary tumor and lymph nodes after preoperative chemotherapy. These findings provide a basis for further appropriate adjuvant therapy in these patients.

Population-based analysis of breast cancer treatment by intrinsic sub-type in Manitoba, Canada

BACKGROUND

Few descriptive epidemiological studies on the incidence, treatment and survival can accurately reflect a whole population. Manitoba, Canada has an accurate cancer registry, a drug information program network and a breast screening program since 1995. This combined with a stable population provides true population data that can accurately describe the region.

METHODS

Using a retrospective cohort design all Breast Cancer cases were obtained from 2004-2010 (N=5399) and grouped by Intrinsic sub-type. Identifiable co-morbidities, prescribed endocrine therapy, staging, surgery, treatment and overall and disease-free survival by intrinsic sub-type were evaluated.

RESULTS

Prevalence of Luminal A (41.7%), Luminal B HER2- (15.6%), Luminal B HER2+ (8.9%), Basal-like(10.8%), and HER2+ non-luminal (5.1%) were consistent with other descriptive studies in Canada and Spain. Over this time period the number of lumpectomies increased 1.7% per year (P=0.007). There was a steady increase of 3.4% per year in the use of aromatase inhibitors (P=0.005). Pre-menopausal patients had an increased proportion of HER2+ and Basal-like sub-types. The 7year overall/disease-free survival percentages for Luminal A, Luminal B HER2-, Luminal B HER2+, Basal-like, and HER2+ non-luminal were 88.7%/83.6, 78.2%/73.0, 81.5%/73.3%, 67.7%/63.2%, 70.4%/65.6% respectively.

CONCLUSIONS

Reasons for variability in the prevalence of intrinsic sub-type by region is not fully understood. Manitoba is unique due the stability of the population, completeness of the registry and length of breast cancer screening program. Few true population-based studies grouped by intrinsic sub-type are available.

IMPACT

Descriptive epidemiological studies guide future research by identifying factors that can affect treatment, recurrence, and survival.