Long-term risk of cancer in membranous nephropathy patients

There is a well-known association between membranous nephropathy (MN) and cancer, and patients with MN usually are examined for cancer at the time of diagnosis. The long-term risk of cancer after MN is not well studied.

Cohort study with record linkage between the Norwegian Kidney Biopsy Registry and Norwegian Cancer Registry.

161 patients with MN from 1988 to 2003.

Patients with MN compared with the age- and sex-adjusted general Norwegian population.

Cancer diagnosis reported through 2003.

Mean duration of follow-up was 6.2 years (range, 0.1 to 15 years). 33 patients developed cancer; including 24 patients with cancer after the diagnosis of MN. Median time from diagnosis of MN to diagnosis of cancer was 60 months (range, 0 to 157 months). Mean annual incidence ratio of cancer was 2.4/100 person-years (2.1/100 person-years in the 0- to 5-year period and 2.8/100 person-years for the 5 to 15 years after kidney biopsy). During the 0 to 15 years after the diagnosis of MN, the expected number of cancers was 10.7, resulting in a standardized incidence ratio of cancer of 2.25 (95% confidence interval, 1.44 to 3.35). In the 5 to 15 years after diagnosis, standardized incidence ratio was 2.30 (95% confidence interval, 1.19 to 4.02). Patients with MN who developed cancer were older (65 versus 52 years; P < 0.001). Patients with cancer and MN had a greater mortality rate than patients without cancer (67% versus 26%; P < 0.001).

Follow-up treatment after MN with cytotoxic and immunosuppressive medications is not known.

An increased risk of developing cancer is observed after the diagnosis of MN, which persists for many years.