Response Rates of Invasive Lobular Cancer in Patients Undergoing Neoadjuvant Endocrine or Chemotherapy

Background: A gap remains in the role of neoadjuvant therapy for patients with ILC. Method: Single-institution retrospective review of patients with ILC who received neoadjuvant therapy between 2008 and 2019. Results: 141 patients met inclusion criteria: 71 neoadjuvant chemotherapy (NACT) and 70 neoadjuvant endocrine therapy (NET). 7/71 (9.9%) patients had a pCR following NACT compared to 1/70 (1.4%) with NET (P = .063). pCR was observed in 5/18 (27.8%) patients with Her2Neu-positive disease following NACT, compared to 2/53 (3.8%) with Her2Neu-negative disease (P = .01). For luminal B tumors, median Ki-67 decrease was similar following NACT and NET (18.3 vs 16.3, P = .26). T category decreased in 59 (42.1%) patients following neoadjuvant therapy, increased in 9 (6.4%), and was unchanged in 72 (51.4%). More patients had an increase (28.6%) than decrease (12.1%) in their N category, including 13/60 (21.7%) who were clinically node-negative at diagnosis and identified to have node-positive disease following neoadjuvant therapy, at definitive surgery. Conclusion: In Her2Neu-negative ILC, the potential of a pCR with NACT or NET is low. Most patients' nodal status and tumor size remain unchanged. There is a potential for pathologic stage to be higher at surgery compared to the clinical stage prior to neoadjuvant therapy.

Automated summary

This study retrospectively examined the effectiveness of neoadjuvant therapy for breast cancer. The results showed that the potential for achieving a complete pathological response in HER2-negative cases is low with either neoadjuvant chemotherapy or neoadjuvant endocrine therapy. Most patients' nodal status and tumor size remained unchanged after neoadjuvant therapy, and there is a potential for the pathological stage to be higher at surgery than the clinical stage prior to neoadjuvant therapy.