The following is a summary of “Competitive Risk of Mortality from Second Primary Malignancy in Bladder Cancer Patients After Radical Cystectomy: Implications for Survival,” published in the February 2023 issue of Urologic Oncology by Hensley et al.
Muscle-invasive bladder cancer (BC) is associated with the highest rate of secondary non-urothelial carcinoma (SNUC) of any solid malignancy and is commonly diagnosed in individuals with overlapping mortality risks. Researchers examined the prevalence, causes and timing of SNUC as an alternative risk factor for mortality in patients with BC who underwent radical cystectomy (RC). This retrospective cohort analysis analyzed data from patients who had RC for cT2-4 N0M0 BC between January 1, 2005 and December 31, 2018 at a single referral hospital with high volume for cT2-4 N0M0 BC. Predictive factors for SNUC were analyzed using a multivariate regression model based on the Fine Gray method. Using a variant of the Kaplan-Meier method, the researchers calculated the cumulative incidence of mortality (CIM).
Approximately 693 patients had a median follow-up of 3.7 years (interquartile range [IQR] 1.9-5.9 years). A total of 85 patients or 12.3% developed SNUC after a median time after RC of 3.0 years (IQR 1.2-5.5 years). Freedom from BC recurrence or metastasis was the only significant predictor of SNUC on multivariable analysis (HR 1.54, 95% CI 1.12-1.76, p=0.019). Primary lung cancer accounted for 24 (3.2% of the cohort) and colon cancer for 9 (1.3%) SNUCs. BC monitoring imaging identified SNUC in 35/52 (67.3%) subjects with primary visceral solid organ tumors. Overall, 38.8% of those diagnosed with SNUC died; The most deadly cancers included pancreatic (62.5%), lung (54.2%) and colon cancer (44.4%). At 12 years after RC, the cumulative incidence of SNUC was 22.1% (95% CI, 16.8-27.9%) and steadily increased over time.
As many as 163 patients (23.5% of all patients) died from BC, while an additional 33 (4.8%) died from SNUC and an additional 94 (13.6%) died from other causes. Comparing CIM for BC before and after RC, researchers found that CIM for BC stabilizes by about 24% about 5 years after RC, but the incidence of death from other causes is steadily increasing. CIM for BC was 27.2% (95% CI: 23.5-31%) and CIM for all other causes was 20.0% (95% CI: 15.8-24.6%) at RC year 9.