Locoregional recurrence after cystectomy in muscle invasive bladder cancer: Implications for adjuvant radiotherapy.

Purpose: We report the patterns of locoregional recurrence (LRR) in muscle invasive bladder cancer (MIBC), and propose a risk stratification to predict LRR for optimizing the indication for adjuvant radiotherapy.
Materials and Methods: The study included patients of urothelial MIBC who underwent radical cystectomy with standard perioperative chemotherapy between 2013 and 2019. Recurrences were classified into local and/or cystectomy bed, regional, systemic, or mixed. For risk stratification modelling, T stage (T2, T3, T4), N stage (N0, N1/2, N3) and lymphovascular invasion (LVI positive or negative) were given differential weightage for each patient. The cohort was divided into low risk (LR), intermediate risk (IR) and high risk (HR) groups based on the cumulative score.
Results: Of the 317 patients screened, 188 were eligible for the study. Seventy patients (37.2%) received neoadjuvant chemotherapy (NACT) while 128 patients (68.1%) had T3/4 disease and 66 patients (35.1%) had N+ disease. Of the 55 patients (29%) who had a recurrence, 31 (16%) patients had a component of LRR (4% cystectomy bed, 11.5% regional 0.5% locoregional). The median time to LRR was 8.2 (IQR 3.3-18.8) months. The LR, IR and HR groups for LRR based on T, N and LVI had a cumulative incidence of 7.1%, 21.6%, and 35% LRR, respectively. The HR group was defined as T3, N3, LVI positive; T4 N1/2, LVI positive; and T4, N3, any LVI. The odds ratio for LRR was 3.37 (95% CI 1.16-9.73, P = 0.02) and 5.27 (95% CI 1.87-14.84, P = 0.002) for IR and HR respectively, with LR as reference.
Conclusion: LRR is a significant problem post radical cystectomy with a cumulative incidence of 35% in the HR group. The proposed risk stratification model in our study can guide in tailoring adjuvant radiotherapy in MIBC.
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