Having higher stage chronic kidney disease (CKD) may increase a patient's risks for adverse outcomes after radical cystectomy (RC) for urothelial carcinoma of the bladder (UCB), a new study finds.
To evaluate the association between preoperative CKD and oncological outcomes, Tohru Nakagawa, MD, PhD, of the University of Tokyo in Japan, and colleagues reviewed the medical records of 594 Japanese patients with UCB (median age 67 years) who underwent RC from 1990 to 2013. Of these, 65.3% had G1 to G2, 20.5% G3a, 8.6% G3b, and 5.6% G4 to G5 preoperative CKD, according to the 3-variable Japanese equation for estimated glomerular filtration rate (eGFR). Since chemotherapy can cause acute kidney injury, patients who received prior neoadjuvant chemotherapy were excluded from the study.
During a median follow-up of 4 years, 200 patients experienced cancer progression and 164 died from UCB. The 5-year progression-free and cancer-specific survival rates were 64.9% and 70.2%, respectively, according to findings published in the World Journal of Urology (2018;36:249-256).
On multivariate analyses, having CKD stage G3b or higher was significantly associated with worse progression-free and cancer-specific survival, along with advanced pT stage and lymph node involvement. Compared with patients who had G1–2 CKD, those with G3b and G4–5 CKD had a significant 1.6-fold and 2.2-fold increased risk of progression, respectively, and 1.7-fold and 2.4-fold increased risk of cancer-specific mortality, respectively. Compared with patients who had pT stage 0–1, those with pT stage 2 and 3–4 had a significant 1.8-fold and 3.2-fold increased risk of progression, respectively, and 1.8-fold and 3-fold increased risk of cancer-specific mortality (CSM), respectively. Patients with positive lymph nodes had a 3-fold increased risk of progression and CSM. Lymphovascular invasion was associated with a 2-fold increased risk of progression and CSM.
“To our knowledge, this is the first study which clearly showed that preoperative CKD stages G3b or greater were significantly associated with poor oncological outcomes in UCB patients who underwent RC,” Dr Nakagawa's team stated.
The underlying reasons for the association are not yet clear. CKD status may be a proxy for less intensive cancer treatment. Or, the investigators speculated, there may be a direct connection between tumor aggressiveness and advancing CKD. Both inflammation and uremic toxins and CKD-induced immunosuppression might promote the growth of aggressive tumors.
The researchers acknowledged that they lacked data on patient comorbidities and important confounders such as hydronephrosis, diabetes mellitus, hypertension, and drug-induced nephrotoxicity. Urinary albuminuria and proteinuria data also were missing.