Intestinal metaplasia of the urinary tract harbors potentially oncogenic genetic variants

In the urinary tract, there is an uncertain relationship between intestinal metaplasia (IM), primary adenocarcinoma, and urothelial carcinoma. Although IM is usually found adjacent to concurrent urothelial carcinoma or adenocarcinoma, small retrospective series have shown that most bladder biopsies with only IM do not subsequently develop cancer. However, IM with dysplasia does seem to be associated with a higher risk of concurrent malignancy or progressing to cancer. Since the molecular landscape of these lesions has remained largely unexplored, there are significant uncertainties about the oncogenic potential of IM in the bladder and urethra. This study investigated the presence of potentially oncogenic genetic variants in cases of IM with and without dysplasia. Twenty-three (23) cases of IM (3 urethra, 20 bladder) were sequenced using a solid tumor next-generation sequencing panel. Of these, five contained IM with high-grade dysplasia (including a case with paired IM-adenocarcinoma and another with paired IM-urothelial carcinoma) and 18 lacked dysplasia. Oncogenic genetic variants were found in all cases of IM with high-grade dysplasia and in five non-dysplastic IM cases, including mutations and copy number variants commonly seen in primary adenocarcinoma of the bladder and urothelial carcinoma. This study demonstrates that IM can harbor potentially oncogenic genetic variants, suggesting that it might represent a cancer precursor or a marker of increased cancer risk in a subset of cases.