Chemotherapy agents are drugs that target and kill rapidly dividing cells and are used to treat cancer. These drugs, however can affect normal cells throughout the body. Because the kidneys and bladder, parts of the urinary tract, function to filter and remove waste from the blood, they are especially susceptible to damage. There are several chemotherapy agents including methotrexate, cisplatin, mytomycin-C and cyclophosphamide that are known to cause damage to the kidneys and bladder.
Renal Toxicity
Renal (kidney) toxicity, also called nephrotoxicity, occurs when the cells in the kidney die, impairing the kidneys' function. If left untreated, this can result in renal failure and even death. Renal toxicity can be caused directly by the chemotherapy agent, as it causes the death of kidney cells. As the cells die, the kidney cannot function at full capacity, leaving waste within the bloodstream.
The chemotherapy agents can also cause renal toxicity by debris from the breakdown of the chemotherapy drug blocking the renal tubes and collecting ducts. This blockage impairs the excretion of the waste, therefore allowing the medication to remain longer in the body, causing more toxicity.
Chemotherapy agents can also indirectly cause renal toxicity by the tumor cells releasing large volumes of ions and metabolites as they die. This cellular debris can result in a blockage of the tubes leading into or out of the kidney, resulting in impaired function and toxicity.
Hemorrhagic Cystitis
Hemorrhagic cystitis is the diffuse (spreading) inflammation of the bladder resulting in hematuria (blood in the urine) and bladder pain. Chemotherapy drugs, especially cyclophosphamide and ifosfamide, are broken down within the body and excreted through the urinary tract system.
The urine that is stored in the bladder contains the debris from the chemotherapy agents that irritate the epithelial (skin) cells in the bladder wall. The cells then slough off, causing inflammation, and the lining of the bladder grows thinner. This results in the formation of ulcers, leading to the bleeding and pain.
Secondary Malignancies
Treatment with certain chemotherapy drugs can lead to the formation of secondary malignancies, meaning new tumors. Patients receiving cyclophophamide, for example, have a 4-fold increase in risk of developing bladder cancer. The development of secondary tumors can occur anywhere from months to many years after the administration of treatment. It is important, therefore, to continue follow-up monitoring, not only to be sure the initial cancer does not return, but also to be sure new tumors in the bladder or kidney do not occur.
