Nonrandom distribution of oncogene amplifications in bilateral breast carcinomas: Possible role of host factors and survival bias.

Amplification of HER2, C-MYC and CCND1 oncogenes is a hallmark of breast cancer (BC); however, its involvement in the bilateral form of this disease has not been investigated yet. In this study, 50 bilateral BC (biBC) pairs (100 tumors) and 72 control unilateral BC were examined using real-time PCR analysis of microdissected archival tissues. In biBC, the frequency of >3-fold oncogene amplification was 6/100 (6%) for HER2, 6/100 (6%) for C-MYC and 7/100 (7%) for CCND1.

Microsatellite instability analysis of bilateral breast tumors suggests treatment-related origin of some contralateral malignancies.

Purpose: High-frequency microsatellite instability (MSI-H) occurs frequently in colorectal cancers and some other tumor types, but is very uncommon in breast cancer. In the earlier study devoted to microsatellite analysis of allelic imbalances, the authors accidentally detected several MSI-H tumors in patients with the bilateral form of breast cancer (biBC). The present study was designed to examine this unexpected phenomenon in more detail.

NBS1 657del5 mutation may contribute only to a limited fraction of breast cancer cases in Russia.

The gene for Nijmegen chromosomal breakage syndrome (NBS1) plays a role in a variety of processes protecting chromosomal stability. Recently, it was suggested in a Polish case-control study that the founder hypomorphic mutation in NBS1, 657del5, which occurs in approximately 0.5% of Slavic subjects, may be associated with an increased risk of breast cancer (BC).