FGFR3 gene alteration and protein expression in upper urinary tract carcinoma: unsuitability of ureteroscopic biopsy specimens for FGFR3 RNA testing.

Among the 36 radical nephroureterectomy-derived tissue specimens, 33 (92%) yielded valid FGFR3 RNA test results; the remaining three (8.3%) showed test failure because of undetectable amplification by reverse transcriptase-polymerase chain reaction.

Of the 33 radical nephroureterectomy specimens with valid amplification, eight (24%) had FGFR3 alterations.

Of these eight specimens, two (25%) were valid for FGFR3 RNA testing; one showed positive concordance with the paired radical nephroureterectomy specimen, whereas the other did not.