Clinical Relevance of Mutation and Its Characteristics in Breast Cancer with Long-Term Follow-Up Date.

BACKGROUND

The mutation is one of the most frequently identified mutations in human cancers and is typically associated with a poor prognosis. However, there are conflicting findings regarding its impact. We aimed to clarify the clinical relevance of mutations across all breast cancer subtypes and treatments utilizing long-term follow-up data.

METHODS

We retrospectively identified the data of breast cancer patients who underwent mutation testing. Stratified log-rank tests and Cox regression analysis were performed to compare oncologic outcomes based on mutation status and the characteristics of these mutations, including types and locations. Mutations in exons 5-9 were identified using polymerase chain reaction-denaturing high-performance liquid chromatography (PCR-DHPLC) and direct sequencing.

RESULTS

Between January 2007 and December 2015, 650 breast cancer patients underwent mutation testing in Gangnam Severance Hospital. The mutations were identified in 172 patients (26.5%), with 34 (19.8%) exhibiting missense hotspot mutations. Patients with mutations (-mutated group) had worse prognosis, demonstrated by a 10-year recurrence-free survival (RFS) rate of 83.5% compared to 86.6% in patients without mutations (HR, 1.67; = 0.026) and a 10-year overall survival (OS) rate of 88.1% versus 91.0% (HR, 3.02; = 0.003). However, subgroup analyses within the -mutated group did not reveal significant differences in oncologic outcomes based on mutation types and locations.

CONCLUSIONS

Our findings establish that mutations are linked to poorer oncologic outcomes in breast cancer across all subtypes. Yet, within the -mutated group, the specific characteristics of mutations do not influence oncologic outcomes.