Renal cell carcinoma overview
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
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Overview
Historical Perspective
Renal cell carcinoma was first described in 1826. Following contradictory hypotheses regarding the origin of renal tumors, it was not until 1960 that Oberling and colleagues showed that renal carcinomas originate from renal cells.
Classification
Classification of renal cell carcinomas according to histopathological subtypes is based on the 1997 classification by Heidelberg and colleagues. Classification may also be according to the stage of renal cell carcinoma, which often is based on Robson classification system or the tumor-lymph node-metastasis (TNM) system.
Pathophysiology
The pathophysiology of renal cell carcinomas plays an important role in differentiating different types of renal cell carcinomas and in choosing appropriate targeted medical therapies. Sporadic forms of clear cell renal carcinomas, the most common form of renal cell carcinomas, have similar pathophysiological mechanisms to those of von Hippel Lindau (VHL) disease. On the other hand, MET proto-oncogene seems to play a role in the disease pathogenesis of papillary forms of renal cell carcinoma. Uniquely also, oncocytomas are benign tumors that arise from type A intercalated cells, whereas chromophobe renal cell carcinoma arises from type B intercalated cells.
Causes
Most renal cell carcinomas develop sporadically. Only a few have genetic predisposition and are associated with known syndromes, such as von Hippel Lindau (VHL), hereditary paragangliomas, leiomyomatosis, and Birt-Hogg-Dube (BHD) syndrome, among several others.
Differentiating Renal cell carcinoma from other Diseases
The differential diagnosis of renal cell carcinomas includes metastastic disease, cysts, abscesses, lymphomas, and other benign and malignant tumors, and associated syndromes.
Epidemiology and Demographics
Renal cell carcinoma is considered the 7th most common cancer in men and 9th most common cancer in women, accounting for approximately 2-3% of malignant tumors in adults. Men are twice more likely to be affected than women with an mean age of presentation at 60 years. Most renal cell carcinomas develop sporadically, while only a small number of cases are of genetic diseases. Clear cell carcinomas are the most common renal cell carcinomas and collecting-duct carcinomas are the least common. Renal cell carcinomas are mostly found incidentally during radiological abdominal work-up.
Risk Factors
Established risk factors for renal cell carcinoma include cigarette smoking, hypertension, end-stage renal failure, analgesic drug use, environmental exposure to carcinogens, and some genetic syndromes.
Screening
There are currently no guidelines for screening for renal cell carcinoma.
Natural History, Complications and Prognosis
The projected 5-year survival is significantly associated with the stage of the tumor at diagnosis. Stage I tumors are associated with more than 90% 5-year survival vs. less than 20% survival for tumors of stage IV. The potential aggression of a tumor has been shown to be associated with tumor size, grade of tumor, and histopathological subtype. High grade tumors greater than 7 cm of clear cell type generally have a higher aggressive potential than low grade tumors smaller than 3 cm of papillary type. Finally, complications vary according to the local extension of the tumor, and the presence of paraneoplastic syndromes and/or metastases.
Diagnosis
Most patients are diagnosed with renal cell carcinoma following the incidental finding of the tumor during abdominal radiological work-up. The gold standard of diagnosis is percutaneous needle biopsy of the involved kidney, with or without imaging-guidance. The most common symptom associated with the disease is hematuria. Physical exam may be unrevealing, or may be positive for signs of local tumor extension, paraneoplastic syndromes, or metastases, such as a palpable abdominal mass, high blood pressure, facial flushing, skin pallor, or other neurological, pulmonary, or musculoskeletal abnormalities. Common laboratory findings may show anemia or polycythemia, hypercalcemia, elevated serum creatinine, elevated liver function tests, ESR, ALP, and LDH. Imaging is an important diagnostic and follow-up procedure in renal cell carcinoma. The use of CT, MRI, CXR, and ultrasound are all feasible options in the work-up, according to the 2013 American Urological Association (AUA) guidelines.
Treatment
Active surveillance is currently emerging as an option for individual cases of small renal cell carcinomas or those with co-morbidities and cannot tolerate intervention. Surgical resection of renal cell carcinoma is the mainstay of therapy for non-metastatic tumors. The choice of partial vs. radical nephrectomy varies according to tumor size, tumor burden, and overall status performance of the patient. Also, laparoscopic intervention is currently an option in select cases. Medical therapy is reserved for patients
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