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Breast cancer is the second leading cause of cancer death among women worldwide and besides life style, age and genetic risk factors, exposure to ionizing radiation is known to increase the risk for breast cancer. Further, DNA copy number alterations (CNAs), which can result from radiation-induced double-strand breaks, are frequently occurring in breast cancer cells. We set out to identify a signature of CNAs discriminating breast cancers from radiation-exposed and non-exposed female patients. We analyzed resected breast cancer tissues from 68 exposed female Chernobyl clean-up workers and evacuees and 68 matched non-exposed control patients for CNAs by array comparative genomic hybridization analysis (aCGH). Using a stepwise forward-backward selection approach a non-complex CNA signature, that is, less than ten features, was identified in the training data set, which could be subsequently validated in the validation data set (p value < 0.05). The signature consisted of nine copy number regions located on chromosomal bands 7q11.22-11.23, 7q21.3, 16q24.3, 17q21.31, 20p11.23-11.21, 1p21.1, 2q35, 2q35, 6p22.2. The signature was independent of any clinical characteristics of the patients. In all, we identified a CNA signature that has the potential to allow identification of radiation-associated breast cancer at the individual level., (© 2018 UICC.)

One of the major consequences of the 1986 Chernobyl reactor accident was a dramatic increase in papillary thyroid carcinoma (PTC) incidence, predominantly in patients exposed to the radioiodine fallout at young age. The present study is the first on genomic copy number alterations (CNAs) of PTCs of the Ukrainian-American cohort (UkrAm) generated by array comparative genomic hybridization (aCGH). Unsupervised hierarchical clustering of CNA profiles revealed a significant enrichment of a subgroup of patients with female gender, long latency (>17 years) and negative lymph node status. Further, we identified single CNAs that were significantly associated with latency, gender, radiation dose and BRAF V600E mutation status. Multivariate analysis revealed no interactions but additive effects of parameters gender, latency and dose on CNAs. The previously identified radiation-associated gain of the chromosomal bands 7q11.22-11.23 was present in 29% of cases. Moreover, comparison of our radiation-associated PTC data set with the TCGA data set on sporadic PTCs revealed altered copy numbers of the tumor driver genes NF2 and CHEK2. Further, we integrated the CNA data with transcriptomic data that were available on a subset of the herein analyzed cohort and did not find statistically significant associations between the two molecular layers. However, applying hierarchical clustering on a 'BRAF-like/RAS-like' transcriptome signature split the cases into four groups, one of which containing all BRAF-positive cases validating the signature in an independent data set., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The nuclear disaster that occurred in Chernobyl in 1986 offered the unique opportunity to study the molecular genetics of one human tumor type, papillary carcinoma of the thyroid gland, associated with a specific etiology. We have analyzed RET rearrangements in post-Chernobyl papillary thyroid carcinomas (n = 29), follicular thyroid adenomas (n = 2), and follicular thyroid carcinoma (n = 1) by interphase fluorescence in situ hybridization (FISH) analysis on paraffin-embedded tissue sections. Paraffin sections were microdissected before use to ensure that only tumor was present. Cell nuclei were scored for the presence of a split FISH signal (separated red and green signal) in addition to an overlapping signal. Only cells with either two overlapping signals or one split and one overlapping signal were counted to ensure that only complete cell nuclei had been scored. In total, 23 of 32 cases (72%) showed RET rearrangements diagnosed by FISH interphase analysis. In all cases, the tumors were composed of a mixture of cells with and without ret rearrangement on FISH. In some cases, this distribution was clearly nonrandom because clustering of rearranged cells was detected within the same tumor nodule. Accordingly, only 31% of the cases positive for rearrangement on FISH also scored positive using RT-PCR. These findings suggest that because RET/PTC rearrangements are not present in a majority of tumor cells, either a fraction of post-Chernobyl papillary thyroid tumors are of multiclonal origin, or ret rearrangement is a later, subclonal event.