Comparison of paclitaxel and docetaxel in dual HER2 blockade: efficacy and safety in neoadjuvant treatment of HER2-positive breast cancer.

Background: Dual HER2 blockade with trastuzumab and pertuzumab combined with neoadjuvant chemotherapy improves outcomes in HER2-positive breast cancer. The optimal taxane backbone (paclitaxel vs. docetaxel) remains unclear.

Methods: This retrospective study included 220 HER2-positive breast cancer patients treated with anthracycline-based chemotherapy followed by dual HER2 blockade with trastuzumab, pertuzumab, and either paclitaxel (80 mg/m² for 12 weeks) or docetaxel (75 mg/m² every three weeks for four cycles). Pathological complete response (pCR), disease-free survival (DFS), overall survival (OS), and toxicity profiles were analyzed.

Results: At the time of diagnosis, 6% of the patients included in the study were at stage I, 70.4% were at stage II, and 23.6% were at stage III. The overall pCR rate was 55%, with no significant difference between the paclitaxel (57.9%) and docetaxel (52.2%) groups (p = 0.418). Higher pCR rates were associated with grade 3 tumors, ER/PR negativity, and Ki- 67 ≥ 20%. Patients achieving pCR had significantly lower relapse rates (2.5% vs. 16.2%, p < 0.001). These factors were significantly associated with pCR in univariate analysis but did not remain independent predictors in multivariate analysis. DFS and OS were higher in the paclitaxel group compared to the docetaxel group (DFS: 96.3% vs. 83.2%, p = 0.025; OS: 100% vs. 95.5%, p = 0.042). Grade 3-4 anemia was more frequent with docetaxel (23% vs. 9%, p = 0.007).

Conclusion: Both paclitaxel and docetaxel are effective in neoadjuvant dual HER2 blockade regimens. Paclitaxel demonstrated better DFS, OS, and a favorable safety profile, supporting its use as a preferred option.