END-STAGE KIDNEY DISEASE AND MALIGNANCY

Cancer incidence is high in patients with end-stage kidney disease (ESKD) compared to the general population. Population-based studies show a significantly increased standardized incidence ratio (SIR) for all cancers in the United States dialysis population compared to the general population. Multiple studies have shown that cancer risk is highest in the first year of dialysis initiation, including among younger patients. There are significant demographic variations in cancer incidence and risk. The risk for kidney (SIR 3.6; CI 3.5 to 3.8) and bladder (SIR 1.5; CI 1.4 to 1.6) cancers were increased, relatively more in younger than older patients and more in female patients (kidney: SIR 4.6, CI 4.3 to 4.9; bladder: SIR 2.7, CI 2.4 to 2.9) than male patients (kidney: SIR 3.2, CI 3.0 to 3.4; bladder: SIR 1.3, CI 1.2 to 1.3). There is a significant variation in the SIR of cancer in dialysis patients, depending on the geographic areas. The risk was most elevated for cancers of the kidney/renal pelvis (SIR, 4.03; 95% CI, 3.88-4.19) and bladder (SIR, 1.57; 95% CI, 1.51-1.64) in US Medicare dialysis patients. Increased risk of incident cancer was observed in dialysis patients with previous transplant failure. SIR during dialysis after transplant failure remained significantly elevated for leukemia, lung cancer, cancers related to kidney, urinary tract, and thyroid cancers, with thyroid cancer incidence significantly higher. The prevalence of several oncogenic viruses, such as hepatitis B and C, is high in ESKD patients. When adjusted for age, sex, and comorbidities, ESKD patients had a 2.41 (95% CI; 1.83-3.16) times increased risk of any human papillomavirus-related cancer compared with population controls. Current recommendations advise against routine cancer screening in patients on dialysis with “limited life expectancy and without signs or symptoms.” However, regular dialysis therapy is an exceptional opportunity for early detection of certain malignancies such as kidney cancer and of the thyroid, which is frequently investigated in the diagnostic program of hyperparathyroidism. Challenges to cancer screening in dialysis patients include vascular calcifications in dialysis patients, high false-positive rates, and mammography interpretation in women with ESKD, which may be more difficult. Tumor markers (TM) are simple and easily measurable tests in diagnosing and clinical management of patients with cancer. However, the kinetics of TM in renal impairment often leads to false-positive results. There are no consistent clinical guidelines for pre-transplant cancer screening in potential kidney transplant recipients with no prior history of malignancy. It may be necessary to implement routine cancer screening protocols in dialysis units undergoing transplant evaluation. The emerging model of personalized cancer screening for the general population may also benefit patients receiving dialysis.