Background: Preoperative chemotherapy (PCT) allows for in vivo testing of treatment effects on tumor and its microenvironment. Aim of this analysis was to evaluate the effect of PCT on tumor biomarker expression and to evaluate the prognostic role of treatment-induced variation of these biomarkers (molecular response).
Methods: Two hundred and twenty-one stage II-III breast cancer patients were included. The following parameters were evaluated at baseline and on surgical specimens after PCT: estrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER2), Ki-67, p53, human epidermal growth factor receptor (EGFR), vascular endothelial growth factor receptor 2 (VEGFR2), and apoptosis.
Results: A pathological complete response was observed in 8.8% of the patients. PCT induced a significant reduction in the expression of ER, PgR, Ki-67, and apoptosis. As by multivariable model, Ki-67 > or = 15% and nodal positivity after preoperative chemotherapy (PCT) were significant predictors of worse disease-free survival [hazard ratio (HR) 3.79, P < 0.0001 and HR 2.31, P = 0.037, respectively]. Ki-67 > or = 15% after PCT was also a significant predictor of overall survival (HR 3.75, P = 0.013). On the basis of these two parameters, patients were classified into three groups: (i) low risk (negative nodes and Ki-67 <15%), (ii) intermediate risk (nodal positivity or Ki-67 > or = 15%), and (iii) high risk (nodal positivity and Ki-67 > or = 15%). As compared with the low-risk group, the HRs for recurrence were 3.1 and 9.3 for the intermediate- and high-risk group, respectively (P = 0.0001); the HRs for death were 2.4 and 6.5 for the intermediate- and high-risk group, respectively (P = 0.042).
Conclusions: Ki-67 and nodal status have been used to generate a simple and easily reproducible prognostic model, able to discriminate patients with worse prognosis among the heterogeneous group of women with residual disease after PCT.