Background

Field cancerization is characterized by areas of normal tissue affected by mutated clones. Bladder field cancerization may explain the development and recurrence of bladder cancer and may be associated with treatment outcomes.

Objective

To investigate the predictive and prognostic roles of field cancerization in patients with high-risk non–muscle-invasive bladder cancer (NMIBC) treated with bacillus Calmette-Guérin (BCG).

Design, setting, and participants

We conducted comprehensive genomic and proteomic analyses for 751 bladder biopsies and 234 urine samples from 136 patients with NMIBC. The samples were collected at multiple time points during the disease course. Field cancerization in normal-appearing bladder biopsies was measured using deep-targeted sequencing and error correction models.

Outcome measurements and statistical analysis

Endpoints included the rates of recurrence and progression. Cox regression and Wilcoxon rank-sum and Fisher’s exact tests were used.

Results and limitations

A high level of field cancerization was associated with high tumor mutational burden (p = 0.007), high tumor neoantigen load (p = 0.029), and high tumor-associated CD8 T-cell exhaustion (p = 0.017). In addition, high field cancerization was associated with worse short-term outcomes (p = 0.029). Nonsynonymous mutations in bladder cancer–associated genes such as KDM6A, ARID1A, and TP53 were identified as early disease drivers already found in normal-appearing bladder biopsies. Urinary tumor DNA (utDNA) levels reflected the bladder tumor burden and originated from tumors and field cancerization. High levels of utDNA after BCG were associated with worse clinical outcomes (p = 0.027) and with disease progression (p = 0.003). High field cancerization resulted in high urinary levels of proteins associated with angiogenesis and proliferation. Limitations include variation in the number of biopsies and time points analyzed.

Conclusions

Field cancerization levels are associated with tumor development, immune responses, and clinical outcomes. utDNA measurements can be used to monitor disease status and treatment response.

Patient summary

Molecular changes in the tissue lining the bladder result in tumor recurrence. Urinary measurements may be used to monitor bladder cancer status and treatment responses.