Risk and prognosis of cancer in patients with nephrotic syndrome.

BACKGROUND

Nephrotic syndrome may be a marker of occult cancer, but population-based studies of this association are lacking. Therefore, we examined the risk and prognosis of cancer in patients with nephrotic syndrome.

METHODS

We conducted this population-based cohort study in Denmark, including all individuals diagnosed with nephrotic syndrome between 1980 and 2010 without a preceding cancer history. We computed the 5-year risk of cancer accounting for competing risk by death and standardized incidence ratios (SIRs) of cancer in patients with nephrotic syndrome relative to the general population. We compared the 5-year mortality for patients with cancer after nephrotic syndrome with that for a cancer cohort without a history of nephrotic syndrome using Cox regression adjusted for age, gender, and comorbidity.

RESULTS

Of 4293 individuals with nephrotic syndrome, 338 developed an incident cancer during a median follow-up of 5.7 years. The 5-year risk of any cancer was 4.7% in patients with nephrotic syndrome, a 73% increased risk (SIR, 1.73; 95% confidence interval [CI], 1.55-1.92). The association was most pronounced for lung cancer, kidney cancer, lymphoma, and multiple myeloma. It was highest within 1 year of nephrotic syndrome diagnosis (SIR, 4.49; 95% CI, 3.68-5.42), but remained increased beyond 1 year (SIR, 1.34; 95% CI, 1.17-1.53). The 5-year mortality after cancer was 68.5% in patients with cancer with nephrotic syndrome and 63.4% in the cancer comparison cohort (adjusted hazard ratio, 1.20; 95% CI, 1.02-1.42).

CONCLUSIONS

Nephrotic syndrome is a marker of occult solid tumors and hematologic malignancies and is associated with a worsened cancer prognosis.