Malignant tumour of the cells that cover and line the kidney. It usually affects persons over age 50 who have vascular disorders of the kidneys. It seldom causes pain, unless it is advanced. It may metastasize to other organs (e.g., lungs, liver, brain, bone) and go unrecognized until these secondary tumours cause symptoms. Blood can appear in the urine early on but is painless and usually disregarded. Even when the cancer is in the early stages, X-ray films can show deformity in kidney structures.
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"Kidney Cancer" redirects here. For Wilms' Tumor/Nephroblastoma, see Wilms' tumor.
Renal cell carcinoma (RCC) is the most common form of kidney cancer arising from the renal tubule. It is the most common type of kidney cancer in adults. Initial treatment is surgery but 90% of the time it is unsuccessful. It is resistant to radiation therapy and chemotherapy, although some cases respond to immunotherapy. Targeted cancer therapies such as sunitinib have improved the outlook for RCC, although they have not yet demonstrated improved survival.
The classic triad is hematuria (blood in the urine), flank pain and an abdominal mass. This is now known as the 'too late triad' because by the time patients present with symptoms, their disease is often advanced beyond a curative stage. Today, the majority of renal tumors are asymptomatic and are detected incidentally on imaging, usually for an unrelated cause.
Other signs may include:
Renal cell carcinoma affects about three in 10,000 people, resulting in about 31,000 new cases in the US per year. Every year, about 12,000 people in the US die from renal cell carcinoma. It is more common in men than women, usually affecting men older than 55.
Kidney cancer both RCC & TCC currently is diagnosed in some 6,600 people in Britain/UK per annum and some 3,600 people who die are recorded as having died of kidney cancer in a given year. The morbidity rate recorded is thought to underestimate the percentage who die of kidney cancer. Often the cause of death recorded on the death certificate may not mention kidney cancer but the subsequent metastases. It is clear that well over 50% of those diagnosed with kidney cancer in Britain will die as a result of the disease.
Why the cells become cancerous is not known. A history of smoking greatly increases the risk for developing renal cell carcinoma. Some people may also have inherited an increased risk to develop renal cell carcinoma, and a family history of kidney cancer increases the risk.
Increasingly there is a belief that inhalation of a diversity of chemicals may be causal and it is also noted that there is a steady increase in diagnosis in women. That a disproportionate percentage of those diagnosed with kidney cancer are obese is increasingly believed to be a significant factor.
People with von Hippel-Lindau disease, a hereditary disease that also affects the capillaries of the brain, commonly also develop renal cell carcinoma, specifically the clear cell type of RCC. Kidney disorders that require dialysis for treatment also increase the risk for developing renal cell carcinoma.
Gross examination shows a yellowish, multilobulated tumor in the renal cortex, which frequently contains zones of necrosis, hemorrhage and scarring.
Light microscopy shows tumor cells forming cords, papillae, tubules or nests, and are atypical, polygonal and large. Because these cells accumulate glycogen and lipids, their cytoplasm appear "clear", lipid-laden, the nuclei remain in the middle of the cells, and the cellular membrane is evident. Some cells may be smaller, with eosinophilic cytoplasm, resembling normal tubular cells. The stroma is reduced, but well vascularized. The tumor compresses the surrounding parenchyma, producing a pseudocapsule.
The characteristic appearance of renal cell carcinoma (RCC) is a solid renal lesion which disturbs the renal contour. It will frequently have an irregular or lobulated margin. 85% of solid renal masses will be RCC. 10% of RCC will contain calcifications, and some contain macroscopic fat (likely due to invasion and encasement of the perirenal fat). Following intravenous contrast administration (computed tomography or magnetic resonance imaging), enhancement will be noted, and will increase the conspicuity of the tumor relative to normal renal parenchyma.
A list of solid renal lesions includes:
In particular, reliably distinguishing renal cell carcinoma from an oncocytoma (a benign lesion) is not possible using current medical imaging or percutaneous biopsy.
Renal cell carcinoma may also be cystic. As there are several benign cystic renal lesions (simple renal cyst, hemorrhagic renal cyst, multilocular cystic nephroma, polycystic kidney disease), it may occasionally be difficult for the radiologist to differentiate a benign cystic lesion from a malignant one. A classification system for cystic renal lesions that classifies them based specific imaging features into groups that are benign and those that need surgical resection is available. At diagnosis, 30% of renal cell carcinoma has spread to that kidney's renal vein, and 5-10% has continued on into the inferior vena cava.
Percutaneous biopsy can be performed by a radiologist using ultrasound or computed tomography to guide sampling of the tumor for the purpose of diagnosis. However this is not routinely performed because when the typical imaging features of renal cell carcinoma are present, the possibility of an incorrectly negative result together with the risk of a medical complication to the patient make it unfavorable from a risk-benefit perspective.This is not completely accurate, there are new experimental treatments.
RCC "elicits an immune response, which occasionally results in dramatic spontaneous remissions." This has encouraged a strategy of using immunomodulating therapies, such as cancer vaccines and interleukin-2 (IL-2), to reproduce this response. IL-2 has produced "durable remissions" in a small number of patients, but with substantial toxicity. Another strategy is to restore the function of the VHL gene, which is to destroy proteins that promote inappropriate vascularization. Bevacizumab, an antibody to VEGF, has significantly prolonged time to progression, but phase 3 trials have not been published. Sunitinib (Sutent), sorafenib (Nexavar), and temsirolimus, which are small-molecule inhibitors of proteins, have been approved by the U.S. F.D.A.
A month later, Sunitinib was approved as well. Sunitinib—an oral, small-molecule, multi-targeted (RTK) inhibitor—and sorafenib both interfere with tumor growth by inhibiting angiogenesis as well as tumor cell proliferation. Sunitinib appears to offer greater potency against advanced RCC, perhaps because it inhibits more receptors than sorafenib. However, these agents have not been directly compared against one another in a single trial.
Recently the first Phase III study comparing an RTKI with cytokine therapy was published in the New England Journal of Medicine. This study showed that Sunitinib offered superior efficacy compared with interferon-α. Progression-free survival (primary endpoint) was more than doubled. The benefit for sunitinib was significant across all major patient subgroups, including those with a poor prognosis at baseline. 28% of sunitinib patients had significant tumor shrinkage compared with only 5% of patients who received interferon-α. Although overall survival data are not yet mature, there is a clear trend toward improved survival with sunitinib. Patients receiving sunitinib also reported a significantly better quality of life than those treated with IFNa. Based on these results, lead investigator Dr. Robert Motzer announced at ASCO 2006 that “Sunitinib is the new reference standard for the first-line treatment of mRCC.”
Temsirolimus (CCI-779) is an inhibitor of mTOR kinase (mamallian target of rapamycin) that was shown to prolong overall survival vs. interferon-α in patients with previously untreated metastatic renal cell carcinoma with three or more poor prognostic features. The results of this Phase III randomized study were presented at the 2006 annual meeting of the American Society of Clinical Oncology (www.ASCO.org).
The outcome varies depending on the size of the tumor, whether it is confined to the kidney or not, and the presence or absence of metastatic spread. The Fuhrman grading, which measures the aggressiveness of the tumor, may also affect survival, though the data is not as strong to support this.
The five year survival rate is around 90-95% for tumors less than 4 cm. For larger tumors confined to the kidney without venous invasion, survival is still relatively good at 80-85%. For tumors that extend through the renal capsule and out of the local fascial investments, the survivability reduces to near 60%. If it has metastasized to the lymph nodes, the 5-year survival is around 5 % to 15 %. If it has spread metastatically to other organs, the 5-year survival rate is less than 5 %.
For those that have tumor recurrence after surgery, the prognosis is generally poor. Renal cell carcinoma does not generally respond to chemotherapy or radiation. Immunotherapy, which attempts to induce the body to attack the remaining cancer cells, has shown promise. Recent trials are testing newer agents, though the current complete remission rate with these approaches are still low, around 12-20% in most series.