Background and p

urpose: Neoadjuvant chemotherapy (NAC) has become the standard treatment method for locally advanced breast cancer. In 2018

researchers established a multivariate predictive model for predicting the probability of axillary complete response (ypN

0

) after NAC in patients with clinical axillary lymph node positive (cN

+

) disease. This study aimed to evaluate the related factors of ypN

0

after NAC

and to verify and modify the Olga Kantor predictive model for breast cancer patients. Methods: A total of 350 consecutive node-positive breast cancer patients who received axillary lymph node dissection (ALND) after NAC in Shandong Cancer Hospital Affiliated to Shandong University were retrospectively analyzed. As the pathological evaluation of the primary breast tumor response in the Olga Kantor model could not be used for preoperative prediction of ypN

0

preoperative image after NAC was incorporated in our study as a surrogate to modify this model. Independent predictive factors were analyzed both in the validation model and the modification model

and the predictive accuracy was assessed by the area under receiver operating characteristic (ROC) curve (AUC) in the two models. Results: Age

molecular subtype

Ki-67 and pathological extent of breast tumor response were independent predictors of ypN

0

in the validation model

while age

molecular subtype and clinical extent of breast tumor response were independent predictors in the modification model (P0.05

respectively). The validation and modification models achieved the AUC of 0.788 and 0.782

respectively (P0.05). In the modification model

patients with predictive score ≤3

4-7 and ≥8 reached ypN0 rates of 2.5% (1/40)

22.4% (51/228) and 68.3% (56/82)

respectively. Conclusion: Olga Kantor model could accurately predict ypN

0

after NAC

and our modification model could reach the same predictive power but was more in line with clinical practice

which could provide a reasonable support for patient selectio

n for sentinel lymph node biopsy (SLNB) after NAC. ALND is suggested in patients with score ≤3

SLNB is suitable for patients with score 4-7

and SLNB is recommended to patients with score ≥8.