Chromosomal alterations in sporadic medullary thyroid carcinoma and correlation with outcome.

Somatic copy number alterations (SCNA) involving either a whole chromosome or just one of the arms, or even smaller parts, have been described in about 88% of human tumors. This study investigated the SCNA profile in 40 well-characterized sporadic medullary thyroid carcinomas by comparative genomic hybridization array. We found that 26/40 (65%) cases had at least one SCNA. The prevalence of SCNA, and in particular of chromosome 3 and 10, was significantly higher in cases with a RET somatic mutation. Similarly, SCNA of chromosomes 3, 9, 10 and 16 were more frequent in cases with a worse outcome and an advanced disease. By the pathway enrichment analysis, we found a mutually exclusive distribution of biological pathways in metastatic, biochemically persistent and cured patients. In particular, we found gain of regions involved in the intracellular signaling and loss of regions involved in DNA repair and TP53 pathways in the group of metastatic patients. Gain of regions involved in the cell cycle and senescence were observed in patients with biochemical disease. Finally, gain of regions associated with the immune system and loss of regions involved in the apoptosis pathway were observed in cured patients suggesting a role of specific SCNA and corresponding altered pathways in the outcome of sporadic MTC.