Importance of monitoring renal function in patients with cancer.

Monitoring renal function in patients with solid tumors and hematologic malignancies is vital to the safe administration of therapeutic agents. Renal impairment is frequent in elderly patients (i.e., age ≥ 65) with cancer, despite normal serum creatinine levels in most patients. Because serum creatinine levels do not accurately reflect clearance rates, renal function should be estimated by calculation (either Cockcroft-Gault or abbreviated Modification of Diet in Renal Disease [aMDRD] equations) or by measuring creatinine clearance using a 24-h urine collection. Additionally, patients with cancer often have preexisting comorbidities or other risk factors that increase the probability of renal impairment before receiving potentially nephrotoxic therapies. Patient age, preexisting renal dysfunction, and chronic comorbidities (e.g., diabetes, kidney disease, hypertension, and cardiac insufficiency) all contribute to the risk of renal impairment. Furthermore, both cancer and its therapies may lead to renal impairment. A number of cancer therapy agents are nephrotoxic, including chemotherapy agents, molecular targeted agents, pain management agents, radiopharmaceuticals, contrast agents used in radiology, and antiresorptive agents, and contrast agents used in radiology are nephrotoxic as well. Undetected decreases in clearance rates by the kidneys can greatly increase exposure to treatment agents, possibly decreasing the safety of treatment and exacerbating renal impairment. In conclusion, all cancer patients, not only those receiving potentially nephrotoxic agents, require renal monitoring.