Loss of heterozygosity in ampulla of Vater neoplasms during adenoma-carcinoma sequence

Background: Ampulla of Vater cancers arise from precancerous lesions and existence of an adenoma-carcinoma sequence is based on morphological observations. Materials and Methods: We studied the loss of heterozygosity (LOH) in 22 adenomas, 32 carcinomas and 10 metastatic lesions using nine dinucleotide-repeated sequences in 3p, 8p, 8q, 9p, 10q, 13q, 17p, 17q, 18q. Result: High LOH frequencies (>50%) of 9p (IFNA) and 17p (TP53) were observed in adenomas and carcinomas. The frequency of LOH is higher in adenoma (55.6%) than in carcinoma (40%) for 8p (D8S261), but it is the same in cases having adenoma. (57.1%) and carcinoma (571%) in the same lesion. LOH for 13q (D13S118), 17q (D17S520) and for 18q (D18S34) were more common in carcinomas than in adenomas, but statistically a significant difference was observed only on 13q (p<0.05). Fractional allelic loss (FAL) is not correlated with any of the clinicopathological parameters. Conclusion: Tumor suppressor genes located in the 8p, 9p and 17p chromosomes might be associated with the early stage of tumorigenesis and that in 13q is involved during the adenoma-carcinoma progression.