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Kidney neoplasias
1. Describe the demographics of renal cell carcinoma (RCC). how many cases of RCC are diagnosed annually, and how many deaths are attributable to this disease? Is RCC more common in males or females? What is the median age at diagnosis of RCC?
In 2016, an estimated 62,700 cases of RCC were diagnosed, and 14,240 deaths were attributable to the disease. Approximately 63% and 65% of diagnoses and deaths, respectively, occurred in males. The median age at diagnosis is 65.
2. What are the three most common histologic subtypes of RCC, and what proportion of RCC cases do they account for?
Clear cell RCC accounts for approximately 80% of cases, while papillary and chromophobe histologies represent 10% and 5% of cases, respectively.
3. What are the clinical features of collecting duct (bellini duct) carcinoma? What clinical disorder is associated with the medullary variant of collecting duct carcinoma?
Collecting duct carcinoma comprises less than 1% of RCC cases, and has a particularly aggressive phenotype. Medullary RCC represents a variant of collecting duct carcinoma, and was first noted to occur among patients with sickle-cell trait.
4. What are common presenting signs of RCC?
Often, RCC presents as an incidental finding on radiographic imaging of the abdomen. With respect to symptoms, common complaints include hematuria and flank pain. In the setting of metastatic disease, patients may note bone pain, palpable adenopathy, or pulmonary complaints (i.e., shortness of breath secondary to bulky lung disease or pleural effusions).
5. What paraneoplastic syndromes are associated with RCC? What is Stauffer’s syndrome?
Nearly 40% of patients with RCC develop paraneoplastic syndromes. RCC produces a range of ectopic hormones, including parathyroid-like hormone, erythropoietin, insulin, gonadotropins, renin, and placental lactogen. Clinically, this may manifest in a range of symptoms and laboratory abnormalities including, but not limited to, hypertension (24%), hypercalcemia (10% to 15%), and erythrocytosis (4%). Stauffer’s syndrome, which occurs in roughly 6% of patients, implies liver function test abnormalities but absent hepatic metastases. This reversible liver dysfunction is pathognomonic for RCC.
6. What gene is disrupted in the majority of sporadic cases of RCC?
The VHL gene is disrupted in up to 70% of sporadic cases of RCC. In approximately 50% of cases, somatic mutations occur, and in 10% to 20% of cases, the gene is hypermethylated. A consequence of VHL mutation is upregulation of hypoxia-induced genes, leading to increased production of moieties such as vascular endothelial growth factor (VEGF). This, in turn, causes increased tumor angiogenesis.
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