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The kidney failure population is at increased risk of cancer and associated mortality. However, the drivers of excess mortality are poorly understood. Relative survival can provide insight into the excess mortality, directly or indirectly, attributed to cancer in the kidney failure population.
We estimated relative survival for people receiving dialysis (n=4089) and kidney transplant recipients (n=3253) with de novo cancer, and for the general population with cancer in Australia and New Zealand (1980-2019). The entire general population was the reference group for background mortality, adjusted for sex, age, calendar year and country. We used Poisson regression to quantify excess mortality ratios.
Five-year relative cancer survival was markedly lower in people receiving dialysis (0.25, 95%CI:0.23-0.26) and kidney transplant recipients (0.55, 95%CI:0.53-0.57) than in the general population with cancer.
The relative survival since cancer diagnosis plateaued for the general population with cancer; 5-year relative survival 0.67 (95%CI:0.67-0.67) and 10-year relative survival 0.65 (95%CI:0.65-0.65). However, relative survival continued to gradually decline in kidney transplant recipients (5-year relative survival 0.55 [95%CI:0.53-0.57] and 10-year relative survival 0.43 [95%CI:0.41-0.45]) and steeply declined for people receiving dialysis (5-year relative survival 0.25 [95%CI:0.23-0.26] and 10-year relative survival 0.09 [95%CI:0.08-0.10]).
Excess mortality was more than double (2.16, 95%CI:2.08-2.25) that of the general population with cancer for people on dialysis and, 34% (95%CI:1.27-2.41) higher for kidney transplant recipients.
Decreased cancer survival in kidney failure may reflect differences between sexes in multi-morbidity burden, reduced access to treatment, or greater harm from or reduced efficacy of treatments. Our findings support research aimed at investigating these hypotheses.