BRCA1 gene mutation rate in breast cancer patients and its clinical significance

Breast cancer commonly occurs in females with increasing incidence. BRCA1 is one tumor suppressor gene and participates in DNA injury and repair. The dysfunction of BRCA1 impairs DNA and elevates the risk of breast or ovarian cancer. This study thus investigated the mutation rate of BRCA gene and its implication for prognosis. A total of 116 breast cancer patients were collected for peripheral blood. Leukocyte DNA was extracted to test germ-line mutation of BRCA1. Cancer tissues were also extracted for DNA, from which somatic mutation of BRCA1 was tested, in addition to MLPA approach. From clinical and pathological parameters, their correlation with BRCA1 gene mutation along with patient prognosis wasanalyzed. In addition, Kaplan-Meier method was used to analyze the survival rate. The overall mutation rate of BRCA1 gene in patients is 20.7%. Among those the mutation rate was 57.1% in all patients with inherited breast/ovarian cancer, significantly higher than those rates in sporadic breast cancer. Further analysis of clinical pathology parameters revealed no significant correlation between BRCA1 gene mutation and patient's age, menstrual status and metastasis. Kaplan-Meier method analyzed patient's diagnosis showed better RFS and OS within five years in patients with BRCA1 mutation compared to wild type ones. By sequencing and MLPA test, we found significantly higher mutation rate of BRCA1 gene in those patients with family history of breast/ovarian cancer compared to those in sporadic cancer patients. Meanwhile those breast cancer patients with BRCA1 mutation had more favorable prognosis.