Neoadjuvant chemotherapy for luminal a breast cancer: Factors predictive of histopathologic response and oncologic outcome.

Background: The benefit of chemotherapy (NAC) for patients with ER/PR positive, HER2 negative breast cancer is unclear. Our aim was to determine factors associated with histopathologic response and oncologic outcome following NAC in this group.

Methods: Consecutive female patients undergoing neoadjuvant therapy and surgery for locally advanced Luminal A breast cancer between 2010 and 2015 were studied. Multivariable linear, logistic, and Cox regression analysis was undertaken.

Results: 114 patients were studied. Pathological complete response (pCR) was achieved in 7.9% of patients, ypN0 in 25.5%, and downstaging in 33.6%. However, 43.9% exhibited a Sataloff C-D response. Tumor grade independently predicted pCR (P = 0.039), while PR score predicted ypN0 (P = 0.017) and downstaging (P=0.029). 5-year invasive disease-free (iDFS) and overall survival (OS) were 68.5 ± 4.7% and 77.7 ± 4.3%, respectively.

Conclusion: After NAC for Luminal A breast cancer, pCR rates are low. Patients with high grade tumors with weak PR expression exhibit the most promising response rates.