[Cancer and the Kidney: A Deadly Embrace].

A deadly embrace occurs between cancer and chronic kidney disease. The estimation of kidney function in cancer patients is of utmost interest due to its direct impact on chemotherapy dosing, selection, and eligibility for chemotherapeutics. Overestimating kidney function (determined as estimated glomerular filtration rate -eGFR) can lead to overdosing and drug toxicity, while underestimating kidney function can prevent patients from receiving novel therapies. Notably, the current measures of eGFR are not validated in transplanted patients yet. The field of onconephrology ranges from nephrotoxicity of existing and novel therapeutics, paraproteinemias, and cancer-associated electrolyte imbalance, fluid and acid-base disturbances, the effects of the destruction of cancer cells, and acute and/or chronic kidney injuries. Recently, the therapeutic armamentarium has been enriched with new agents that interfere with specific proteins involved in oncogenesis. These are the so-called target therapies, which although acquired as "targeted" therapies do not have absolute specificity and selectivity and tend to inhibit multiple targets, often involving the kidney. Renal biopsy may be critical in managing these adverse effects. Moreover, primary hematological and oncological disorders can have significant kidney implications in the form of glomerular or nonglomerular diseases presenting with proteinuria, hematuria, hypertension, and kidney function decline, specifically including cast nephropathy or systemic light chain amyloidosis, and paraneoplastic glomerulopathies that occur as a result of occult malignancy, such as Membranous Nephropathy and Minimal Change disease.