What is Renal Cell Cancer?
Renal cell carcinomas (RCCs), a type of kidney cancer that starts in the kidney cortex (outer part of the kidney), account for 80% to 85% of all primary kidney tumors. Another form, transitional cell carcinomas, which start in the renal pelvis (the center part of the kidney where urine collects), make up about 8%. Tumors like oncocytomas, collecting duct tumors, angiomyolipomas, and renal sarcomas are less common. In children, the most common kidney tumors are nephroblastoma and Wilms tumor. Medullary renal carcinoma is a rare but severe type of kidney cancer that occurs in individuals with sickle cell disease. Other less common types of kidney cancers include clear cell, papillary, and chromophobe malignancies.
What Causes Renal Cell Cancer?
Doctors don’t know the exact cause of renal cell carcinoma (RCC), a type of kidney cancer. However, several factors can increase a person’s risk of developing it. These factors include being older, having obesity or high blood pressure, suffering from chronic kidney failure, undergoing dialysis treatment, suffering from polycystic kidney disease, being of African American descent, having sickle cell disease, and having kidney stones.
There are some inherited diseases that can also increase the risk of RCC. These include tuberous sclerosis, Von Hippel-Lindau syndrome, Birt-Hogg-Dube syndrome, hereditary papillary kidney cancer, and hereditary leiomyomatosis and renal cell carcinoma (HLRCC).
Moreover, certain studies suggest that if you are exposed to some substances in the workplace, you may have a higher risk of RCC. These substances include cadmium, herbicides, asbestos, and trichloroethylene.
Risk Factors and Frequency for Renal Cell Cancer
RCC, also known as Renal Cell Carcinoma, is the most prevalent form of kidney cancer in adults. This type of cancer is most commonly found in men aged between 50 and 70. The frequency of RCC is different across the world, with the highest numbers seen in the Czech Republic and North America. In the US, close to 63,000 new instances and about 14,000 deaths are logged every year. Interestingly, the number of RCC cases in the US has been increasing since the mid-2000s, particularly among early-stage tumors.
Signs and Symptoms of Renal Cell Cancer
At first, when kidney cancer (or renal cell cancer) is still small (under 3 centimeters), there usually aren’t any symptoms. Around one in four patients doesn’t notice any signs, and the tumor is only found during routine scans.
As the tumor gets bigger, symptoms might start to show. These can include:
- Blood in the urine (hematuria)
- Back pain
- A lump on one side of your waist (flank mass)
- Tiredness (fatigue)
- Weight loss
- Anemia (a lack of red blood cells)
- Fever
- High levels of calcium in your blood
The traditional ‘clinical triad’ of symptoms—flank pain, hematuria, and flank mass—only happens in about 10% of patients. If someone has all three of these symptoms, it usually means the cancer is fairly advanced.
Testing for Renal Cell Cancer
If you’re being tested for renal cell carcinoma (RCC), also known simply as kidney cancer, there are a few tests that your doctor may use. Initial tests might include a urine test to check for blood in your urine, called hematuria, or a urine analysis to look for cancer cells. A blood test may be used to check for anemia or high calcium levels, as both of these can be indicators of kidney cancer.
If these tests suggest possible RCC, the next step is usually a special type of ultrasound that examines the kidneys and bladder. If the ultrasound shows a mass in the kidney or a complicated cyst, then a CT scan (a type of X-ray) of the kidneys, ureters, and bladder, both with and without a dye that helps visualize internal structures, is used. This CT scan will take several frames over time to get a complete picture of the kidneys and surrounding areas.
If the ultrasound brings back a negative result, but there is unexplained blood in your urine, a CT scan should be the next test. This is because small kidney masses and tiny kidney stones can often be missed using ultrasound alone.
Renal cell carcinoma will often appear unusually bright on a CT scan after the application of contrast dye. This test is important as it helps judge the extent or stage of the disease by checking the kidney vein, inferior vena cava (a major vein carrying blood to your heart), or nearby organs for possible invasion by cancer. It can also detect if the cancer has spread to bones in your abdomen or pelvis, but to examine other bones, a whole body scan would be more effective. Furthermore, a chest CT scan should be performed as RCC can often spread to the lungs.
PET-CT, which creates detailed images of the inside of the body, is another imaging technique that can be used, although its use is controversial. However, it might be helpful in detecting distant or far-flung metastases.
Lastly, an MRI scan of the abdomen can be used to diagnose and stage RCC just as effectively as a CT scan, however, it can sometimes be affected by things like the patient moving during the scan because it takes longer to capture the images
Treatment Options for Renal Cell Cancer
The treatment for kidney tumors depends on the stage, or severity, of the tumor. Staging helps doctors understand how big the tumor is and how far it has spread.
- For stage I kidney tumors that are smaller than 7 centimeters and only in the kidney, the usual treatment is an operation called a nephrectomy or partial nephrectomy. This surgical procedure removes either all or a part of the kidney and usually cures the condition. If your tumor is not quite so big or you have more than one, your doctor might suggest radiofrequency ablation or cryotherapy. These are treatments that use heat or cold to destroy the tumor. If you are an older patient with a short life expectancy and not a good candidate for surgery, your doctor might decide to just monitor your condition with regular medical imaging, as many kidney tumors grow slowly.
- For stage II kidney tumors, the usual treatment is a laparoscopic radical nephrectomy. This is a minimally invasive surgical procedure that removes the entire kidney using small incisions and a camera.
- For stage III kidney tumors, the standard treatment is typically an open radical nephrectomy. This surgical procedure removes the entire kidney through a larger incision. Your doctor might also suggest removing the adrenal gland or some lymph nodes if they show signs of tumor infiltration during a CT scan.
Unfortunately, stage IV kidney tumors can’t be cured. But your doctor will work with you to manage symptoms and aim to prolong life as much as possible. Various treatments like tumor embolization (blocking the blood supply to the tumor), external-beam radiation therapy (use of high-energy beams to kill cancer cells), and nephrectomy (removing the kidney) may be utilized. But these techniques are not used to cure the disease, but to help reduce symptoms and increase survival. Immunotherapy and chemotherapy, which help the body’s immune system fight the cancer or kill cancer cells, can also help prolong life. Certain medications may also be used to lessen the risk of complications from bone metastases, which are secondary tumors that have spread to your bones.
What else can Renal Cell Cancer be?
The following conditions can resemble other solid kidney tumors and so are considered in the differential diagnosis:
- Kidney oncocytoma
- Lipid-poor renal angiomyolipoma
- Kidney metastases
- Kidney lymphoma
- Solitary fibrous tumor (very rare)
- Multilocular cystic nephroma
Additionally, the following kidney abnormalities can mimic Renal Cell Carcinoma (RCC):
- a prominent column of Bertin
- kidney abscess
- kidney infarct
- complex kidney cyst
A prominent column of Bertin is often uncertain on an ultrasound and needs further confirmation with a CT scan or MRI.
A kidney abscess often comes with supporting clinical symptoms like pyelonephritis, a high white blood cell count, fever, and chills.
A kidney infarct is usually linked with vascular problems like renal vein thrombosis or trauma.
To distinguish a complex kidney cyst from kidney cancer, radiologists use the Bosniak classification system.
What to expect with Renal Cell Cancer
The future outlook or prognosis for a patient greatly depends on the development stage and the type of cells affected by the disease.
* For those in Stage 1, a whopping 90% of patients tend to live for at least five more years.
* On the other hand, patients who are already in Stage 2 have a 50% chance of living for at least five more years.
* Those in Stage 3 face a slightly grimmer outlook, with only 30% of patients living for at least another five years.
* For patients in Stage 4, the most severe stage, only 5% of them might live for another five years.
When we look at specific types of diseases like kidney cancer, the type of kidney cancer also impacts the outlook. Papillary RCC (a type of kidney cancer) generally offers the best outlook with 90% of these patients living for five more years. Clear cell cancer subtype (another type of kidney cancer) comes next, with a 70% five-year survival rate.
