Words of wisdom. Bladder cancers arise from distinct urothelial sub-populations

Radical cystectomy for pT1 urothelial carcinoma of bladder not amenable to TURBT: Long-term results

PURPOSE

This study sought to identify factors associated with survival of pT1 urothelial carcinoma of bladder (UCB) after radical cystectomy (RC).

METHODS

This study consists of 114 pT1 UCB [primary 83, recurrent 31, none were amenable to transurethral resection (TUR)] treated by radical cystectomy. Survival analysis using Cox regression tests were performed to identify factors associated with survival of pT1 UCB after RC.

RESULTS

Pelvic lymph node (LN) status, age and lymphovascular invasion (LVI) are associated with survival of pT1 UCB after RC; recurrent pT1 UCB of high grade origin (HGO) tends to have poorer CSS than primary pT1 UCB or recurrent pT1 UCB of low grade origin (LGO) (5-year and 10-year CSS rates was 75% and 73% for primary cases; 77% and 77% for recurrent pT1 UCB of LGO; and 56% and 37% for recurrent pT1 UCB of HGO, p = 0.078).

CONCLUSIONS

LN status, age and LVI were significantly associated with survival of pT1 UCB after RC. Recurrent pT1 UCB of HGO should be managed with radical cystectomy in a timely fashion given that these cases tend to have poorer CSS than primary pT1 UCB after RC, even if they did not progress to muscle-invasive bladder cancer (MIBC).

Quantitative genome-wide methylation analysis of high-grade non-muscle invasive bladder cancer

High-grade non-muscle invasive bladder cancer (HG-NMIBC) is a clinically unpredictable disease with greater risks of recurrence and progression relative to their low-intermediate-grade counterparts. The molecular events, including those affecting the epigenome, that characterize this disease entity in the context of tumor development, recurrence, and progression, are incompletely understood. We therefore interrogated genome-wide DNA methylation using HumanMethylation450 BeadChip arrays in 21 primary HG-NMIBC tumors relative to normal bladder controls. Using strict inclusion-exclusion criteria we identified 1,057 hypermethylated CpGs within gene promoter-associated CpG islands, representing 256 genes. We validated the array data by bisulphite pyrosequencing and examined 25 array-identified candidate genes in an independent cohort of 30 HG-NMIBC and 18 low-intermediate-grade NMIBC. These analyses revealed significantly higher methylation frequencies in high-grade tumors relative to low-intermediate-grade tumors for the ATP5G2, IRX1 and VAX2 genes (P<0.05), and similarly significant increases in mean levels of methylation in high-grade tumors for the ATP5G2, VAX2, INSRR, PRDM14, VSX1, TFAP2b, PRRX1, and HIST1H4F genes (P<0.05). Although inappropriate promoter methylation was not invariantly associated with reduced transcript expression, a significant association was apparent for the ARHGEF4, PON3, STAT5a, and VAX2 gene transcripts (P<0.05). Herein, we present the first genome-wide DNA methylation analysis in a unique HG-NMIBC cohort, showing extensive and discrete methylation changes relative to normal bladder and low-intermediate-grade tumors. The genes we identified hold significant potential as targets for novel therapeutic intervention either alone, or in combination, with more conventional therapeutic options in the treatment of this clinically unpredictable disease.