The relationship between the mutations of PIK3CA, C-KIT genes and clinicopathological characteristics, prognosis of breast cancer with axillary lymph node metastasis

JIANG Hao; WANG Tiantian; ZHOU Tao

Abstract：Objective To explore the relationship between the mutation of PIK3CA, C-KIT genes and clinicopathological characteristics, prognosis of breast cancer with axillary lymph node metastasis. Methods The archival paraffin-embedded tissues from 84 cases of breast cancer with axillary lymph node metastasis were collected. The Ion Torrent sequencing technique was used to detect the mutation rates and distributions of PIK3CA and C-KIT genes. The relationship between the mutations of PIK3CA, C-KIT genes and clinicopathological characteristics( age, menstruation, number of lymph node metastasis, tumor thrombus, tumor size, clinical stage, ER/PR and HER-2 expression) was investigated. The patients enrolled were divided into mutated group and non-mutated group and followed up for 3-year disease-free survival rate. Results All mutations were missense mutations with the rates of 63.1%( 53/84) and 15.5%(13/84) for PIK3CA and C-KIT genes, respectively. Seven patients with PIK3CA mutation were in exon 9, 8 in exon 13, 24 in exon 20 and 14 in exons 13 and 20. All patients with C-KIT mutation were located in exon 10. Mutations in the two genes were relevant to HER-2 expression, while only the PIK3CA mutation were related to clinical stage and ER/PR expression. The 3-year disease-free survival rate was 75.5% in PIK3CA mutated group and 48.4% in PIK3CA non-mutated group or 76.9% in C-KIT mutated group and 62.0% in C-KIT non-mutated group, without significant differences( P>0.05) . The factors( age, menstruation, number of lymph node metastasis, tumor size, clinical stage, ER/PR expression, HER-2 expression, PIK3CA mutations and C-KIT gene mutations) were not independent prognosis factors of breast cancer with lymph node metastasis. Conclusion The mutation rate of PIK3CA gene is high and relevant to clinical stage, ER/PR and HER-2 expression. Only the relevance to HER-2 expression is observed in C-KIT mutation. Mu- tations in both genes may play a certain role in the development of breast cancer and axillary lymph node metastasis.