Kidney Biopsy in Patients with Cancer along the Last Decade: A Multicenter Study.

Background: Currently, following the new advances in cancer treatments and the increasing prevalence of kidney disease in the population, more kidney biopsies are being performed. The aim of our study is to analyze clinical and histological characteristics of patients with active solid organ malignancy who underwent kidney biopsy. This is a multi-center collaborative retrospective study supported by groups GLOSEN/Onconephrology from the Spanish Society of Nephrology. Clinical, demographical and histological data were collected.

Results: A total of 148 patients with cancer who underwent a kidney biopsy from 12 hospitals were included. 64.3% men and mean age of 66.9 years old. The indications for biopsy were acute renal injury (67.1%), proteinuria (17.1%), exacerbated chronic kidney disease (8.2%), and chronic kidney disease (7.5%). Most frequent malignances were lung (29.1%) and abdominal (25%), with 49.7% metastatic cancer. As oncospecific treatment, 28% received chemotherapy, 29.3% immunotherapy, 19.3% specific therapies, and 2.1% conservative treatment. At the time of kidney biopsy, median creatinine was of 2.58 mg/dL [1.81-4.1 (IQ 25-75)], median urine protein-to-creatinine ratio of 700 mg/g [256-2463 (IQ 25-75)] and 53.1% presented hematuria. The most frequent renal biopsy diagnoses were: acute interstitial nephritis (39.9%), acute tubular necrosis (8.8%), IgA nephropathy (7.4%) and membranous nephropathy (6.1%). Median follow-up was 15.2 months [5.7-31.4 (IQ 25-75)].

Conclusions: There is a new trend in kidney disease and cancer patients in terms of diagnosis and treatment. Acute interstitial nephritis has established itself as the most common kidney injury in patients with cancer who underwent a kidney biopsy. Renal biopsy is a valuable tool for diagnosis, treatment, and prognosis of solid organ cancer patients with kidney damage.