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.