Oncogene Amplification and Prognosis in Breast Cancer: Relationship with Systemic Treatment

In the present study, we aimed to clarify the potential of oncogene amplifications as markers for the prediction of (i) (relapse-free) survival, (ii) response to first-line endocrine therapy and (iii) subsequent chemotherapy in patients with recurrent breast cancer. To attain this goal, amplification of different oncogenes (HER-2/neu, c-MYC and INT-2) was studied in primary tumors of a series of 259 patients with breast cancer (median follow-up of 72 mo). Of these tumors, 49.8% did not contain an amplification of any of the oncogenes studied, whereas in the amplified subgroup, INT-2 was amplified in 13%, HER-2/neu in 24% and c-MYC in 20% of the tumors. In univariate analysis, INT-2 amplification was associated with an increased risk of relapse (p < 0.03), especially in the subgroups of 85 node-negative (p = 0.05) and 156 ER/PgR-positive patients (p = 0.01). Cox multivariate regression analysis showed that c-MYC was the only oncogene whose amplification was significantly related with the rate of relapse. With respect to amplification in patients developing metastatic disease, who received first-line hormonal therapy (n = 114), HER-2/neu amplification was associated with a less favorable response to endocrine therapy (objective response rate only 17% and a progression-free survival (PFS) of only 4% at 12 mo). Interestingly, distinct INT-2 amplification might predict a better response to endocrine therapy (objective response rate of 56%, and a PFS after relapse of 42% at 12 mo).(ABSTRACT TRUNCATED AT 250 WORDS)