Kidney failure occurs when the kidneys lose their ability to effectively filter waste products and excess fluids from the blood. These organs play a vital role in maintaining the body’s internal balance, regulating blood pressure, and producing hormones. Cancer can lead to kidney failure through various mechanisms, encompassing both the direct impact of the cancer itself and the side effects of its treatments.
How Cancer Directly Affects Kidney Function
Cancer can impair kidney function through physical obstruction of the urinary system. Tumors originating in or near the urinary tract, such as in the bladder, prostate, or cervix, can grow and compress the ureters. This blockage, known as obstructive nephropathy, causes urine to back up into the kidneys, leading to swelling and damage to kidney tissue over time. This increased pressure progressively reduces filtering capacity.
Some cancers directly invade or infiltrate kidney tissue, compromising its structure and function. Renal cell carcinoma, a type of kidney cancer, directly destroys kidney cells as it grows. Cancers originating elsewhere, like lymphomas or leukemias, can also spread to the kidneys. This direct cellular infiltration disrupts kidney architecture and function.
Certain cancers produce substances that indirectly harm the kidneys, a phenomenon known as paraneoplastic syndromes. For instance, multiple myeloma can lead to the overproduction of abnormal proteins that deposit in the kidney tubules, blocking filtration and causing damage. Other cancers can trigger immune responses that inadvertently attack the kidney’s filtering units, leading to conditions like paraneoplastic glomerulonephritis. These circulating substances or immune complexes cause inflammation and scarring.
Metabolic abnormalities induced by cancer can also stress and damage the kidneys. Hypercalcemia is a common complication of advanced cancers. High calcium levels can impair the kidney’s ability to concentrate urine and lead to calcium deposits in kidney tissue, resulting in chronic kidney injury. Tumors can also cause electrolyte imbalances, further burdening kidney function.
Kidney Damage from Cancer Treatments
Chemotherapy agents are a significant cause of kidney damage, known as nephrotoxicity. Drugs like cisplatin, used in various cancers, directly damage the cells lining the kidney tubules, impairing reabsorption and filtration. Methotrexate, another common chemotherapy drug, can precipitate in the kidney tubules if not properly hydrated, leading to obstruction and acute kidney injury. Ifosfamide can cause Fanconi syndrome, a disorder where the kidney tubules fail to reabsorb essential nutrients, leading to their loss in urine.
Newer immunotherapies, while effective against cancer, can sometimes trigger immune-related adverse events that affect the kidneys. Checkpoint inhibitors, for example, can lead to interstitial nephritis, where the immune system attacks the kidney’s interstitial tissue. This inflammation can cause a rapid decline in kidney function. It involves an overactivation of the immune system that extends beyond cancer cells to healthy tissues.
Radiation therapy, when directed at or near the kidneys, can also cause kidney damage. Radiation nephropathy occurs when high doses of radiation lead to inflammation and scarring of kidney tissue. The risk depends on the radiation dose, the volume of kidney tissue irradiated, and the patient’s overall kidney health. This damage can manifest months or even years after treatment.
Some targeted therapies, designed to block cancer growth pathways, can also have kidney-related side effects. Certain drugs targeting vascular endothelial growth factor (VEGF) can affect the blood vessels within the kidneys, leading to proteinuria (protein in the urine) or high blood pressure, which can stress the kidneys. Other targeted agents might cause electrolyte imbalances that indirectly impact kidney function.
Supportive care medications and diagnostic procedures used during cancer treatment can also affect kidney health. Certain antibiotics administered to prevent or treat infections can be nephrotoxic, especially in patients with pre-existing kidney conditions. Pain medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs), can reduce blood flow to the kidneys, particularly in dehydrated individuals. Contrast dyes used in imaging tests can also temporarily impair kidney function, especially in vulnerable patients.
Identifying Signs of Kidney Failure
Reduced urine output or changes in urination frequency can signal impaired kidney function. Individuals might notice they are urinating less often or producing a smaller volume of urine. Conversely, some people may experience an increase in nighttime urination as the kidneys struggle to concentrate urine. Any persistent deviation from normal urination warrants attention.
Fluid retention is another common sign of kidney failure, leading to swelling. This edema often appears in the legs, ankles, or feet, as kidneys fail to remove excess sodium and water. The swelling can also manifest as puffiness around the eyes or in the hands, contributing to weight gain.
Persistent fatigue, weakness, and malaise are frequently reported symptoms. The kidneys’ inability to remove toxins from the blood leads to a buildup of waste products that can cause weakness and reduced energy. Anemia, often associated with kidney failure due to decreased production of erythropoietin, further contributes to fatigue.
Gastrointestinal symptoms such as nausea, vomiting, and loss of appetite can occur as waste products accumulate. These toxins irritate the digestive system, leading to unwellness and a metallic taste in the mouth. This can make eating difficult and contribute to unintentional weight loss.
Muscle cramps or weakness can develop due to electrolyte imbalances, such as calcium, phosphorus, and potassium. Shortness of breath may result from fluid accumulation in the lungs or from anemia. Confusion or difficulty concentrating can also arise from the buildup of toxins affecting brain function.
Itching or dry skin is another symptom, often caused by waste products irritating nerve endings. The skin may also appear pale or yellowish due to anemia and uremic toxins. A metallic taste in the mouth or ammonia breath may occur due to urea and other nitrogenous waste products.