ESR1 and breast cancer: These showed a positive correlation between the expression of mesenchymal-/stroma-related markers and therapeutic resistance, including for chemotherapy, targeted therapy, radiotherapy, and immunotherapy, although at times this has been controversial.147–157 For example, in the context of estrogen receptor (ER)-negative breast cancer, Farmer et al.147 have reported that upregulation of the genes within stromal metagene exhibits a significant predictive effect on the resistance to neoadjuvant chemotherapy with 5-fluorouracil, epirubicin, and cyclophosphamide.