Lefaucheur C et al. (2006) Membranous nephropathy and cancer: epidemiologic evidence and determinants of high-risk cancer association. Kidney Int 70: 1510–1517

Adult-onset nephrotic syndrome is frequently caused by membranous nephropathy (MN). Although several studies have indicated that cancer might cause secondary MN, this relationship has not been validated by comparison of the observed cancer incidence in an MN population with that expected from general population data.

To address this issue, Lefaucheur et al. examined the association of cancer with MN in a cohort of 240 patients with MN. Twenty-four of the participants had cancer at the time of renal biopsy or were diagnosed with malignancy within the following year, revealing a higher incidence of cancer—primarily carcinoma of the lung or prostate—in the MN population than in the general population (standardized incidence ratio 9.8 for men and 12.3 for women). In the MN population, older patients and heavy smokers were more likely to be diagnosed with cancer. Patients with cancer-associated MN had a significantly higher number of inflammatory cells infiltrating their glomeruli than did those with idiopathic MN (P = 0.001); the researchers calculate that eight cells per glomerulus is the best cutoff value for this novel predictive marker to distinguish cancer-associated MN from idiopathic MN (specificity 75%, sensitivity 92%).

Patients with an estimated glomerular filtration rate ≥15 ml/min/1.73 m2 were significantly less likely to survive if they had cancer (P<0.001); 44% of deaths in this group were secondary to neoplasia. A positive correlation was found between remission of cancer and remission of nephrotic syndrome, indicating a causal relationship between nephrotic-range proteinuria and carcinoma.