Aim: Upper urinary tract urothelial carcinoma (UUTUC) is an uncommon neoplasm frequently discovered at a high-stage disease. The prognosis of disseminated UUTUCs is poor despite the use of platinum-based chemotherapy. The aim of the study was to evaluate HER2 overexpression and amplification in a series of 83 UUTUCs.
Materials and methods: All tumors were formalin fixed. TNM stage, grade, lymphovascular invasion, surgical margins, morphologic variants were reviewed by 2 pathologists. All tumors were immunostained with anti-HER2 antibody. HER2 gene amplification was determined by dual-color in situ hybridization. Gene amplification was defined by an HER2/CEN 17 ratio >2.2.
Results: HER2 immunostaining was observed in 33/83 tumors. Twelve cases were 2+ score and 2 cases were 3+ score. HER2 in situ hybridization was evaluable in 75/83 cases. Amplification was observed in 6 (7%) cases. All amplified tumors were of high grade and 4/6 were stage pT3. A strong correlation between HER2 overexpression and amplification was noted (P<0.0001). HER2 overexpression and amplification were correlated with the pN+ stage but not with specific survival or recurrence.
Conclusions: These results suggest that HER2 amplification is a rare event in UUTUC but may be of interest for targeted therapy in selected high-grade and high-stage tumors.