Impact of variant histology on disease aggressiveness and outcome after nephroureterectomy in Japanese patients with upper tract urothelial carcinoma

Background Patients with urinary bladder urothelial carcinoma (UC) with variant histology have features of more advanced disease and a likelihood of poorer survival than those with pure UC. We investigated the impact of variant histology on disease aggressiveness and clinical outcome after radical nephroureterectomy (RNU) in Japanese patients with upper tract UC (UTUC). Information on variant histology might guide appropriate patient selection for adjuvant therapy after RNU. Methods We enrolled 502 UTUC patients treated with RNU in this retrospective cohort study, and analyzed associations of variant histology with clinicopathological variables and disease-specific survival. Results The median follow-up was 41.4 months. A total of 60 (12.0 %) UTUC patients had variant histology. UTUC with variant histology was significantly associated with advanced pathological T stage (pT ≥ 3), higher tumor grade (G3), and more lymphovascular invasion ( P