HR⁺/HER2⁻乳腺癌PIK3CA基因突变与淋巴结转移及转移负荷的相关性分析OA

Objective To investigate the association between PIK3CA mutation status and the occurrence and burden of lymph node metastasis in patients with HR+/HER2-invasive breast cancer.Methods A total of 73 patients with HR+/HER2-invasive breast cancer were retrospectively enrolled and divided into a mutant group(n=40)and a wild-type group(n=33)according to PIK3CA mutation status.Baseline clinicopathological characteristics,lymph node metastasis rate,and metastatic burden were compared between the two groups.Metastatic burden was further analyzed among patients with lymph node metastasis-positive(LN⁺).Intergroup comparisons were performed using the χ² test,Fisher's exact test,or Mann-Whitney U test,as appropriate.Univariate Logistic regression analysis was used to evaluate the association between PIK3CA mutation and lymph node metastasis.Disease-free survival(DFS)was analyzed using the Kaplan-Meier method and Log-rank test.Results Among the 73 patients,PIK3CA mutations were detected in 40 cases,with a mutation rate of 54.8%(40/73).The lymph node metastasis rate was significantly higher in the PIK3CA mutation group than in the wild-type group[75.0%(30/40)vs.39.4%(13/33),P=0.005].Univari⁃ate Logistic regression analysis showed that PIK3CA mutation was associated with lymph node metastasis(OR=4.62,95%CI:1.74-13.01,P=0.003).Among LN⁺ patients(n=43),the median number of metastatic lymph nodes[3(1,5)vs.2(1,4)]and the proportion of high-burden metastasis(≥4 metastatic lymph nodes)[43.3%(13/30)vs.30.8%(4/13)]were higher in the PIK3CA mutation group than in the wild-type group,but the differences were not statistically significant(P=0.225 and P=0.439,respectively).No significant difference was observed in the distribu⁃tion of lymph node metastatic patterns between the two groups(P=0.542).Kaplan-Meier survival analysis showed no obvious separation of DFS curves between the two groups(Log-rank P=0.113).Conclusion PIK3CA mutation was associated with the occurrence of lymph node metastasis in HR-positive/HER2-negative breast cancer.Among LN⁺ pa⁃tients,the PIK3CA-mutant group showed a trend toward higher metastatic burden,but the differences did not reach statistical significance and require further validation in larger cohorts.Because of the limited number of DFS events during follow-up,the effect of PIK3CA mutation on DFS could not be adequately evaluated in the present study.