Cancer incidence among US Medicare ESRD patients receiving hemodialysis, 1996-2009

Abstract

Background: Patients with end-stage renal disease (ESRD) receiving dialysis have been reported to have increased risk of cancer. However, contemporary cancer burden estimates in this population are sparse and do not account for the high competing risk of death characteristic of dialysis patients.

Study design: Retrospective cohort study.

Setting & participants: US adult patients enrolled in Medicare's ESRD program who received in-center hemodialysis.

Factors: Demographic/clinical characteristics.

Outcomes: For overall and site-specific cancers identified using claims-based definitions, we calculated annual incidence rates (1996-2009). We estimated 5-year cumulative incidence since dialysis therapy initiation using competing-risk methods.

Results: We observed a constant rate of incident cancers for all sites combined, from 3,923 to 3,860 cases per 100,000 person-years (annual percentage change, 0.1; 95% CI, -0.4 to 0.6). Rates for some common site-specific cancers increased (ie, kidney/renal pelvis) and decreased (ie, colon/rectum, lung/bronchus, pancreas, and other sites). Of 482,510 incident hemodialysis patients, cancer was diagnosed in 37,128 within 5 years after dialysis therapy initiation. The 5-year cumulative incidence of any cancer was 9.48% (95% CI, 9.39%-9.57%) and was higher for certain subgroups: older age, males, nonwhites, non-Hispanics, nondiabetes primary ESRD cause, recent dialysis therapy initiation, and history of transplantation evaluation. Among blacks and whites, we observed 35,767 cases compared with 25,194 expected cases if the study population had experienced rates observed in the US general population (standardized incidence ratio [SIR], 1.42; 95% CI, 1.41-1.43). 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).

Limitations: Claims-based cancer definitions have not been validated in the ESRD population. Information for cancer risk factors was not available in our data source.

Conclusions: These results suggest a high burden of cancer in the dialysis population compared to the US general population, with varying patterns of cancer incidence in subgroups.

Keywords: Hemodialysis; US Renal Data System (USRDS); cancer incidence; cancer risk factor; carcinoma; chronic kidney failure; claims-based cancer definition; diagnostic code; end-stage renal disease (ESRD); malignancy; tumor.

Figure 1

Adjusted annual incidence rates of cancer diagnoses from 1996 through 2009 for: (A) all sites and (B) site-specific cancers. Rates were adjusted for age, sex, race, cause of end-stage renal disease, and dialysis vintage in years. Incident cases were defined as the first cancer diagnosis of the year among patients without a history of cancer in the last 6 months of the previous calendar year. Other cancers were defined as all other site-specific cancers (eg, cancers of the esophagus, stomach, and liver). The sum of the site-specific cancer rates exceeds the rate for any cancer due to patients diagnosed with multiple cancer sites on the same date. Abbreviation: NHL, non-Hodgkin lymphoma.

Figure 2

Adjusted cancer incidence rates by strata for the top 4 most prevalent cancer sites in years 1996 to 2009. Incident cases were defined as the first cancer diagnosis of the year among patients without a history of cancer in the last 6 months of the previous calendar year. Rates were adjusted for age, sex, race, cause of end-stage renal disease (ESRD), and years on dialysis therapy. Age adjustment was performed for 4 strata (18-44, 45-64, 65-74, and ≥75 years), although only 2 categories are presented due to limited case numbers in the 18- to 44-year age group. The subgroup of interest was omitted from the adjustment for each respective subgroup category.

Figure 3

The cumulative incidence of any cancer among patients with end-stage renal disease undergoing hemodialysis, accounting for death as a competing event. The cumulative incidence is denoted by a solid line and the 95% confidence intervals are denoted by a dotted line. Time at risk for a cancer diagnosis began at 9 months after dialysis therapy initiation.

Figure 4

The standardized cumulative incidence of any cancer among patients with end-stage renal disease (ESRD) undergoing hemodialysis, accounting for the competing risk of death. Time at risk for a cancer diagnosis began at 9 months after dialysis therapy initiation. Figures were stratified by patient characteristics, including: (A) age at dialysis therapy initiation, (B) sex, (C) race, (D) ethnicity, (E) primary cause of ESRD, (F) year of dialysis therapy initiation, and (G) history of kidney transplantation evaluation. Cumulative incidence functions were standardized to the total study population by combining the cumulative incidence function with inverse probability of exposure weights that account for case-mix characteristics (age at dialysis therapy initiation, sex, race, ethnicity, primary cause of ESRD, and year of dialysis therapy initiation) measured at baseline.