A paradigm for oncogene complementation in human breast cancer

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)

Steroid hormone receptor immunohistochemistry and amplification of c-myc protooncogene. Relationship to disease-free survival in breast cancer

BACKGROUND

It is important to develop parameters that aid in prognosticating which patients with breast cancer are more likely to have a rapid disease course and therefore might benefit from early aggressive therapies.

METHODS

Specimens from two groups of women, deliberately selected because their clinical courses differed greatly, were studied to detect amplification of the protooncogenes c-myc, int-2, and C-erbB-2/neu by slot-blot assay, the estrogen receptor (ER), and the progesterone receptor (PR) by both biochemical and immunohistochemical procedures (ERICA and PRICA). One group of 50 patients had a prolonged disease-free interval after initial surgery (mean, 6.4 years); the other group of 52 women had had rapid disease recurrence (mean, 1.4 years) or progression (5 patients died of disease within 1 year of diagnosis). The patients were selected from 1700 consecutively accessioned cases if they fit the study criteria and sufficient tissue was available for oncogene hybridization studies.

RESULTS

The two groups differed statistically by stage, number of involved axillary lymph nodes, ERICA and PRICA results (P = 0.001), and amplification of c-myc (P = 0.003). The percentage of patients with rapid disease recurrence and progression increased from 0-93% when risk factors changed from best case (ERICA and PRICA results, positive; c-myc, not amplified; and axillary nodes, not involved) to worst case (ERICA and PRICA findings, negative; c-myc, amplified; and axillary nodes, involved).

CONCLUSIONS

Women with these worst-case parameters were more likely to have a recurrence sooner and rapidly progressive disease. They might benefit from early aggressive therapeutic measures.

Prognostic factors in human primary breast cancer: comparison of c-myc and HER2/neu amplification

Amplification of oncogenes in primary tumours may have prognostic and/or therapeutic significance for patients with breast cancer. We have studied HER2/neu and c-myc amplification together with steroid receptors in human primary breast tumours and related the outcome with (relapse-free) survival. A strong inverse correlation was found between HER2/neu amplification and the presence of oestrogen and progesterone receptors. Actuarial 5-years survival showed that breast cancer patients with c-myc amplification in their primary tumours experience a shorter relapse-free survival, especially in node-negative and in receptor-positive tumours, whereas HER2/neu amplification may be of prognostic value for overall survival in receptor-negative tumours. Overall, in our hands, c-myc amplification appeared to be a more potent prognosticator than HER2/neu amplification in human primary breast cancer.

Prevalence of amplification of the oncogenes c-myc, HER2/neu, and int-2 in one thousand human breast tumours: Correlation with steroid receptors

The frequency of oncogene amplification described in the literature shows a large fluctuation, which could be attributed to the study of relatively small series of tumours, to selection of subgroups of patients, or, especially in retrospective studies, to selection of tumour material from the tumour-bank. To address this question, we have studied amplification of c-myc, HER2/neu and int-2/bcl-1 genes in a series of 1052 collected human breast tumours. The retrospective and prospective subgroups in this collected series of tumours were of equal size. c-myc was amplified in 17.1%, HER2/neu in 18.7% and int-2/bcl-1 in 14.1%, of all breast cancer specimens studied. In the retrospective subgroup the prevalence of amplification was 18.1% for c-myc; 22.6% for HER2/neu and 11.6% for int-2/bcl-1, whereas in the prospective subgroup an incidence of amplification of 16.1%, 15.1% and 16.3% for c-myc, HER2/neu and int-2/bcl-1, respectively was observed. HER2/neu amplification was negatively correlated with oestrogen receptor (ER) and progesterone receptor (PR) status (P less than 0.0001; for both), c-myc amplification was more prevalent in the PR-negative subpopulation (P less than 0.05) and int-2/bcl-1 amplification was positively correlated with ER status (P less than 0.001).

c-myc gene amplification in selected node-negative breast cancer patients correlates with high rate of early relapse

In breast cancers with histologically negative axillary nodes selected for high frequency of recurrence, the amplification of c-myc, erbB-2 and int-2 genes was found to concern, respectively 25% (16/65), 31% (25/81) and 14% (10/70) of tumours. Their relation with tumour progression expressed by relapse-free survival is reported. Using univariate analyses, c-myc amplified tumours showed significant association with early (30-month period after diagnosis) (P = 0.0013) and intermediate (50-month period after diagnosis) (P = 0.0398) risks of recurrence. In contrast, only a trend towards higher relapse was observed in erbB-2 amplified breast cancers with respect to later events (occurring over the first 30-month period). Multivariate analyses indicated that c-myc amplification is an independent prognostic factor stronger than oestrogen receptor status and tumour size to define a high risk subset in node-negative patients selected for high frequency of recurrence.