Amplification in tumors and benign tissue of breast cancer patients.

Inappropriate expression of the c-erb B2 gene has been associated with aggressive tumor behavior in breast cancer. In this study the c-erb B2 amplification was investigated both in the tumors and benign breast tissue of the patients by competitive PCR. The technique combines the sensitivity and speed of PCR with coamplification of a single copy reference gene to achieve quantitative results. Gene copy numbers in excess of 3 copies were observed in tumors of 7 patients but not in the normal tissue samples. We conclude that the increase in the gene copy numbers is a result of the tumorigenic changes occurring in the cancer cell.