Taylor Harris1, Ankur Sheel1, Yang Zong2, Lloyd M Hutchinson2, Kristine M Cornejo3, Lukas Bubendorf4, Jennifer Yates5, Andrew H Fischer6. 1. University of Massachusetts Medical School, Worcester, Massachusetts. 2. Department of Pathology, University of Massachusetts Memorial Health Care, Worcester, Massachusetts. 3. Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts. 4. Department of Pathology, University of Basel, Basel, Switzerland. 5. Department of Urology, University of Massachusetts Memorial Health Care, Worcester, Massachusetts. 6. Department of Pathology, University of Massachusetts Memorial Health Care, Worcester, Massachusetts. Electronic address: Andrew.Fischer@umassmemorial.org.
Abstract
INTRODUCTION: Cytology and cystoscopy are used to detect urothelial carcinoma (UC), but together they still fail to detect some UC cases and are not suitable for screening asymptomatic individuals. Mutations are present in more than 98% of UC, mutations have therapeutic significance, and they can be detected by next generation sequencing (NGS) in urine samples. We review the role of NGS in UC detection. MATERIALS AND METHODS: Comprehensive literature review on UC genetics, economics of NGS, and previous reports of UC detection by NGS. RESULTS: The raw costs of NGS have decreased to about 14,000 base pairs per penny, making it appear economically feasible to use NGS widely. Reported NGS assays fall short of predicted sensitivity. Decreased sensitivity is attributed to a low frequency of mutant alleles in many urine samples. Attempts to increase the percentage of mutant alleles, by using cell-free urinary DNA, or by using cell sorting and microfluidics, have been unsuccessful or remain unproven. However, cytologic examination can immediately enable NGS: Urine cytologies with sufficient proportions of abnormal cells could be directly triaged to NGS with high sensitivity for UC detection. For cases with a low proportion of abnormal cells, cytologically targeted microdissection of cells for NGS should maintain sensitivity and decrease sequencing costs. Cytologically targeted urothelial cells for NGS could allow a screening test for low grade UC. CONCLUSIONS: Cytology is immediately poised to allow NGS to improve the diagnosis of UC, allowing NGS to be an ancillary test for atypical cytologies, and potentially allowing a screening test for low-grade UC.
INTRODUCTION: Cytology and cystoscopy are used to detect urothelial carcinoma (UC), but together they still fail to detect some UC cases and are not suitable for screening asymptomatic individuals. Mutations are present in more than 98% of UC, mutations have therapeutic significance, and they can be detected by next generation sequencing (NGS) in urine samples. We review the role of NGS in UC detection. MATERIALS AND METHODS: Comprehensive literature review on UC genetics, economics of NGS, and previous reports of UC detection by NGS. RESULTS: The raw costs of NGS have decreased to about 14,000 base pairs per penny, making it appear economically feasible to use NGS widely. Reported NGS assays fall short of predicted sensitivity. Decreased sensitivity is attributed to a low frequency of mutant alleles in many urine samples. Attempts to increase the percentage of mutant alleles, by using cell-free urinary DNA, or by using cell sorting and microfluidics, have been unsuccessful or remain unproven. However, cytologic examination can immediately enable NGS: Urine cytologies with sufficient proportions of abnormal cells could be directly triaged to NGS with high sensitivity for UC detection. For cases with a low proportion of abnormal cells, cytologically targeted microdissection of cells for NGS should maintain sensitivity and decrease sequencing costs. Cytologically targeted urothelial cells for NGS could allow a screening test for low grade UC. CONCLUSIONS: Cytology is immediately poised to allow NGS to improve the diagnosis of UC, allowing NGS to be an ancillary test for atypical cytologies, and potentially allowing a screening test for low-grade UC.