Prognostic significance of minor high grade component in non-invasive papillary urothelial carcinoma of urinary bladder: (A study of 273 consecutive cases over a period of 3 years).

PURPOSE: Our study aimed to determine the prognostic significance of minor high-grade components (HGC) in non-invasive papillary urothelial carcinomas compared with pure low-grade and high-grade tumors. MATERIAL AND METHODS: We retrospectively retrieved 273 in-house cases of non-invasive papillary urothelial carcinomas (pTa) from 2016 to 2018 for which follow up data was available in hospital archives. We stratified our data into four main groups (G). G1, pure low-grade (n = 164); G2, HGC ≤5 % (n = 17); G3, HGC >5 % to ≤25 % (n = 14); and G4, pure high-grade (n = 78). Prognosis was assessed in terms of recurrence, grade and stage of progression, metastasis, and death. The mean follow up duration was 34.72 ± 20 months (range 20-60 months). RESULTS: All four groups showed no difference in tumor recurrence (G1 81.7 %, G2 88.2 %, G3 92.9 %, G4 92.3 % p-value 0.183). In terms of grade progression, there was no significant difference in G2 35.3 % and G3 35.7 % and both groups showed worst prognosis compared to G1 16.5 % p-value 0.04. Regarding stage progression (G1 6.7 %, G2 23.5 %, G3 28.6 %, G4 41% p-value 0.001), metastasis (G1 5.5 %, G2 5.9 %, G3 7.1 %, G4 17.9 % p-value 0.01) and death (G1 4.3 %, G2 5.9 %, G3 7.1 %, G4 15.4 % p-value 0.02) there was no significant difference in G2 and G3 and both groups showed worst prognosis than G1 and better than G4. CONCLUSION: Urothelial carcinomas with minor high-grade component ≤25 % behaved worst than pure low grade and better than pure high grade and should be treated as distinct grade entity.