Independence of cytotoxic drug sensitivity profiles and receptor subtype of invasive ductal breast carcinoma demonstrated by the histoculture drug response assay (HDRA).

Aim: Breast cancer can be divided into four subtypes: luminal-A, luminal-B, HER-2 enriched and triple negative breast cancer (TNBC) by the presence or absence of receptors. Each subtype has a typical clinical behavior and prognosis. Many chemotherapeutic agents are used clinically for breast cancer. The histoculture drug response assay (HDRA) is used for selection of effective chemotherapeutic agents for individual patients Materials and Methods: In the present study, the HDRA was used for eleven frequently-used single-agent or combinations on the four subtypes of breast cancer in order to determine the correlation of drug sensitivity profile and breast-cancer subtype. Fifty invasive ductal breast carcinoma patients who underwent cancer surgery and adjuvant chemotherapy between January 2012 and January 2013 had their tumors analyzed in the HDRA. Age, gender, height and weight, tumor-nodes-metastasis (TNM) stage, immunohistochemical (IHC profiles, breast-cancer subtypes and HDRA results were recorded. Results: The inhibition rate (IR) of each agent or combination for each breast-cancer subtype was determined. Drug to drug IRs were statistically distinct in all subtypes (p<0.05) but no correlation between response to chemotherapeutic agents and breast-cancer subtype was found (p=0.851 by two-way ANOVA test). Conclusion: The clear difference between average sensitivity of the chemotherapeutic agents tested and lack of correlation with breast-cancer subtype suggest the importance of individualized treatment for breast-cancer patients.