Basal cell carcinomas of the scalp after radiotherapy for tinea capitis in childhood: A genetic and epigenetic study with comparison with basal cell carcinomas evolving in chronically sun-exposed areas.

BACKGROUND: Basal cell carcinoma (BCC) has been mostly associated with sun exposure, but ionizing radiation is also a known risk factor. It is not clear if the pathogenesis of BCC, namely at a genomic and epigenetic level, differs according to the underlying triggering factors. OBJECTIVE: The present study aims to compare genetic and epigenetic changes in BCCs related to ionizing radiation and chronic sun exposure. METHODS: Tumor samples from BCCs of the scalp in patients submitted to radiotherapy to treat tinea capitis in childhood and BCCs from sun-exposed areas were analysed through array comparative genomic hybridization (array-CGH) and methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) to detect copy number alterations and methylation status of specific genes. RESULTS: Genomic characterization of tumor samples revealed several copy number gains and losses in all chromosomes, with the most frequent gains observed at 2p, 6p, 12p, 14q, 15q, 18q, Xp and Yp, and the most frequent losses observed at 3q, 14q, 16p, 17q, 22q, Xp, Yp and Yq. We developed a statistical model, encompassing gains in 3p and 16p and losses in 14q and 20p, with potential to discriminate BCC samples with sporadic aetiology from BCC samples that evolve after radiotherapy in childhood for the treatment of tinea capitis, which presented statistical significance (P = 0.003). Few methylated genes were detected through MS-MLPA, most frequently RARB and CD44. CONCLUSIONS: Our study represents a step forward in the understanding of the genetic mechanisms underlying the pathogenesis of BCC and suggests potential differences according to the underlying ris k factors.

Multiple Basal Cell Carcinomas of the Scalp After Radiotherapy: Genomic Study in a Case With Latency Period Over 80 Years.

ABSTRACT: Basal cell carcinoma (BCC) has been linked mostly to ultraviolet radiation exposure, but ionizing radiation has also been implicated in the genesis of a subset of BCCs occurring after radiotherapy. We present a 93-year-old woman with 4 BCCs of the scalp after radiotherapy for tinea capitis, diagnosed after a latency period of over 80 years. The largest lesion was located on the right temporal region and corresponded to a BCC of mixed type, with nodular, infiltrative, and micronodular components. We performed genomic study with array comparative genomic hybridization in samples from each BCC, which revealed more imbalances in the largest lesion than in the remaining ones, correlating with its higher histological complexity. Furthermore, this was the only lesion presenting loss at 2p22.3, where is mapped the BIRC6 gene associated with regulation of apoptosis, and loss at 16q24.3, where is mapped FANCA gene, responsible for DNA repair and maintenance of chromosome stability. Despite these differences, there were aberrations shared by all tumor samples, suggesting a common genetic signature. Our report describes, to the best of our knowledge, the longest latency period between exposure to radiotherapy and the diagnosis of BCC. The genomic study showed imbalances common to all tumor samples but also differences that could explain their heterogeneity in terms of histological subtype and biological potential. In addition, these differences could also be a consequence of different times in the evolution of the lesions at the moment of presentation, thus having a diverse combination of accumulated genomic imbalances.

Development of a genomic predictive model for cholangiocarcinoma using copy number alteration data.

AIMS: Cholangiocarcinoma (CC) is a rare tumour arising from the biliary tract epithelium. The aim of this study was to perform a genomic characterisation of CC tumours and to implement a model to differentiate extrahepatic (ECC) and intrahepatic (ICC) cholangiocarcinoma. METHODS: DNA extracted from tumour samples of 23 patients with CC, namely 10 patients with ECC and 13 patients with ICC, was analysed by array comparative genomic hybridisation. A support vector machine algorithm for classification was applied to the genomic data to distinguish between ICC and ECC. A survival analysis comparing both groups of patients was also performed. RESULTS: With these whole genome results, we observed several common alterations between tumour samples of the same CC anatomical type, namely gain of Xp and loss of 3p, 11q11, 14q, 16q, Yp and Yq in ICC tumours, and gain of 16p25.3 and loss of 3q26.1, 6p25.3-22.3, 12p13.31, 17p, 18q and Yp in ECC tumours. Gain of 2q37.3 was observed in the samples of both tumour subtypes, ICC and ECC. The developed genomic model comprised four chromosomal regions that seem to enable the distinction between ICC and ECC, with an accuracy of 71.43% (95% CI 43% to 100%). Survival analysis revealed that in our cohort, patients with ECC survived on average 8 months less than patients with ICC. CONCLUSIONS: This genomic characterisation and the introduction of genomic models to clinical practice could be important for patient management and for the development of targeted therapies. The power of this genomic model should be evaluated in other CC populations.

Genomic characterisation of multiple myeloma: study of a Portuguese cohort.

Multiple myeloma (MM) genomic complexity reflects in the variable patients' clinical presentation. Genome-wide studies seem to be a reasonable alternative to identify critical genomic lesions. In the current study, we have performed the genomic characterisation of a Portuguese cohort of patients with MM by array comparative genomic hybridisation. Overall, the most frequently detected alterations were 13q deletions, gains of 1q, 19p, 15q, 5p and 7p and trisomy 9. Even though some identified genomic alterations were previously associated with a prognostic value, other abnormalities remain with unknown, but putative significance for patients' clinical practice. These genomic alterations should be further assessed as possible biomarkers.