What is Renal Cancer?
The most frequent kind of kidney cancer is known as renal cell carcinoma, also called hypernephroma or Grawitz tumor. This type makes up more than 90% of kidney cancers in adults. Other forms of kidney cancer are transitional cell carcinomas found in the kidney’s central region, which act similarly to bladder cancers. There’s also an uncommon kind of kidney cancer called renal sarcoma. This discussion will primarily focus on renal cell carcinoma (RCC), which accounts for over 3% of all cancer cases in adults and comes in several different forms based on how they look under the microscope.
RCC is more common in older adults, typically between 50 to 70 years old, and men are about twice as likely to get it as women.
What Causes Renal Cancer?
The main thing that increases your chances of getting kidney cancer, or renal cell carcinoma (RCC), is smoking — whether it’s cigarettes, pipes or cigars. Being significantly overweight, especially in women, also raises your risk. It’s thought that cutting out tobacco and managing your weight could cut cases of kidney cancer by half.
Other factors that up your odds include having high blood pressure, chronic kidney failure, or exposure to certain chemicals through your work, like trichloroethylene. On the other hand, moderate alcohol drinking (about two glasses a day), eating lots of fruits and vegetables, and regularly eating fatty fish have been linked to a lower risk of kidney cancer.
Recent studies have shown that a gene called VHL could be involved in the development of the most common type of RCC, clear cell-RCC (CCRCC), in both isolated cases and those running in families. Another genetic mutation, in the MET gene, is a feature of the familial type of another type of kidney cancer, papillary-RCC (PRCC), but PRCC that develops randomly can have many more different molecular changes associated with it.
Around 4% of kidney cancers are caused by rare inherited conditions, such as:
– Von Hippel-Lindau (VHL) Syndrome: This is linked to developing cysts and tumors in a variety of organs, such as tumours in the pancreas and brain, ovarian cysts and pheochromocytoma (tumors in the adrenal gland), alongside various clear cell RCC tumours.
– Hereditary Leiomyomatosis and Aggressive Papillary Carcinoma Syndrome: This is a dominant genetic disease associated with a mutation in the FH gene and can lead to early spread of the disease.
– Hereditary Papillary Carcinoma: This is also a dominant genetic disease and involves a MET gene mutation. It leads to bilateral (in both kidneys) and multiple papillary tumors and may have additional abnormal genes.
– Birt-Hogg-Dubé syndrome: This is a dominant genetic disease due to mutations in the BHD gene, which codes for the protein folliculin. It presents a range of kidney tumor types and includes skin conditions like fibrofolliculomas, trichodiscomas, and acrochordons. Lung cysts may also occur.
– Tuberous Sclerosis Syndrome: This presents with mutations in TSC1 and TSC2 genes that code for the proteins hamartin and tuberin. It manifests with multiple bilateral kidney tumors and CCRCC along with other health issues outside the kidneys.
Risk Factors and Frequency for Renal Cancer
Since 1975, there has been a steady growth in the number of cases of Renal Cell Carcinoma (RCC), a type of kidney cancer. This increase has slowed down in recent years, thanks to early detection made possible by advanced imaging techniques. Over half of RCC cases are detected by chance.
RCC accounts for more than 3% of all adult cancers and comes in different forms. In 2020, it’s estimated that 73,750 cases of kidney-based cancers will be diagnosed, making up 5% of all cancers in males and 3% of all cancers in females. Tragically, it is anticipated that 14,830 people will succumb to the disease. The tumor is most common in the elderly, particularly those between the ages of 60 and 70, with men being twice more likely to develop the disease than women. However, the mortality rate for RCC has decreased by about 1% every year since 2008.
On a positive note, the 5-year survival rate for patients diagnosed early with RCC is quite high, at 93%. About two-thirds of all RCC diagnosis happens at early stages. Generally, the survival rate for all cancers originating from the kidney and renal pelvis stands at 75%.
Signs and Symptoms of Renal Cancer
Renal cell carcinomas (RCCs) often go unnoticed until the disease has advanced, with over half of these kidney tumors found accidentally. Surprisingly, only between 10 to 15% of people show the typical symptoms which include flank pain, blood in urine, and a sensation of fullness on the side of the abdomen. It was found that about 60% of patients had blood in their urine without experiencing any other symptoms. Other symptoms that may develop include fatigue, weight loss, fever, night sweats, malaise, high blood pressure, and anemia. In some cases, enlargement of the veins in the scrotum may occur as a result of the tumor growing into the kidney vein and the large vein carrying deoxygenated blood from the lower half of the body to the heart, leading to the blockage of the vein that drains the testicle.
Painful, sharp, band-like back pain might be due to the collapse of a vertebra and pressure on the spinal cord caused by the cancer spread. RCCs are sometimes nicknamed the “great pretender” because they can cause a variety of syndromes that mimic other conditions. These cancers can produce chemicals that lead to an increased calcium level in the blood, overproduction of red blood cells, and Cushing syndrome.
It’s vital to note that about one-third of people with this type of cancer have it spread to other body parts at the time of diagnosis. The areas where cancer most frequently spreads include the lungs, bones, liver, central nervous system, and other parts of the body.
- Flank pain
- Blood in the urine
- Sensation of fullness on the side of the abdomen
- Fatigue
- Weight loss
- Fever
- Night sweats
- Malaise
- High blood pressure
- Anemia
- Painful, sharp, back pain
Testing for Renal Cancer
If your doctor suspects that you might have kidney cancer (known as renal cell carcinoma or RCC), they will likely start with some initial lab tests. These might include analyzing your urine to see if there are any unusual cells present, especially if the doctor thinks you might have bladder cancer too. They might also do a blood test to check for signs of anemia and problems with platelet cells. Platelets are tiny blood cells that help your body form clots to stop bleeding. Another blood test might be done to measure your erythrocyte sedimentation rate (ESR), which can indicate inflammation in your body.
Your doctor will also check your kidney function and electrolytes. Electrolytes are minerals in your body that have an electric charge. They are in your blood, urine and body fluids. Maintaining the right balance of electrolytes helps your body’s blood chemistry, muscle action and other processes.
Kidney cancer is often associated with a range of other medical conditions known as paraneoplastic syndromes. These include high levels of calcium in the blood (hypercalcemia), an overproduction of red blood cells (erythrocytosis), and liver dysfunction named Stauffer syndrome. To look for these, your doctor will order a number of other lab tests.
Imaging studies can be used to confirm whether you have kidney cancer and help plan your treatment. Methods like magnetic resonance imaging (MRI) and computed tomography (CT) scans can be used to differentiate between different types of renal cell carcinoma. For example, clear cell renal cell carcinomas (CCRCC) are usually hypervascular, meaning they have an excess of blood vessels, on dynamic contrast-enhanced CT scans or MRIs. On the other hand, papillary renal cell carcinomas (PRCCs) usually show the low signal intensity and are hypovascular, meaning they have a lack of blood vessels. Chromophobe renal cell carcinomas (ChRCC) often have a homogeneous solid appearance and a central radial scar with what’s known as “spoke-wheel” enhancement.
A number of other imaging tests may also be used depending on your circumstances. These include renal ultrasonography, CT scans of the abdomen and pelvis, chest X-ray or CT for lung metastasis, renal arteriography and venography for assessing blood flow, bone scans and scans of the head, if metastasis (spread of the cancer) is suspected. MRI might be used to check for involvement of the large vein that carries blood from the lower half of the body back to the heart (the inferior vena cava) or the spread of the cancer to other parts of the body.
If your doctor thinks your kidney cancer might be inherited they might recommend genetic testing. And if there are suspicious areas seen on the imaging, a biopsy (sample of tissue) may be taken using ultrasound or CT for guidance.
Research is also ongoing to identify markers in the blood or urine that might be able to help diagnose and monitor kidney cancer. However, at present, no such markers have been validated for use in kidney cancer, so imaging remains the most important tool for diagnosis and monitoring of the disease.
Treatment Options for Renal Cancer
The treatment options for renal cell carcinoma (RCC), which is a type of kidney cancer, depend on the stage of the disease. This makes it crucial to accurately determine the stage of the cancer to ensure effective treatment. Staging refers to how much the cancer has spread.
For Stage 1a, where the tumor is still only in the kidney, the goal is to completely cure the disease. This is typically done through surgery to remove the tumor, ideally with a procedure called a partial nephrectomy that preserves as much of the kidney as possible. After the surgery, it’s recommend to have follow-up scans at least once per year, either via a CT scan or an MRI, for surveillance purposes.
In Stage 1b, either partial or complete removal of the kidney (known as radical nephrectomy) can be performed, both with similar results. After surgery, patients are advised to undergo abdominal scans between 3 to 12 months and then every year for three years to monitor for any recurrence. Regular chest X-rays are also conducted annually for the same period.
In Stages 2 and 3, removal of the entire kidney (radical nephrectomy) is usually recommended. Patients will undergo periodic abdominal and chest scans every few months for the first three years, followed by yearly scans up to 5 years thereafter. Additional imaging tests might be recommended based on the patient’s specific case.
For Stage 4, which is when cancer has spread to other parts of the body, systemic targeted therapies have become the standard treatment. These include drugs that interfere with tumor growth (e.g. sunitinib, sorafenib, pazopanib, and axitinib), or drugs that affect specific components of cancer cells (e.g., temsirolimus and everolimus). For patients with metastatic RCC, where the cancer has spread to distant organs, combining the removal of the kidney with immunotherapy can improve survival compared to immunotherapy or targeted therapies alone. Follow-up imaging tests are carried out every few months to monitor the disease’s progress and response to treatment.
What else can Renal Cancer be?
About half of kidney cancers, also known as renal cell carcinomas (RCCs), are detected by chance since they typically don’t cause any symptoms. Hence, if a kidney scan reveals a mass, it’s possible it might be RCC.
However, there are other conditions to consider when a patient shows a kidney mass, as they can look like RCC:
- Abscess (a collection of pus)
- Angiomyolipoma (a non-cancerous tumor)
- Renal oncocytoma (a non-cancerous tumor)
- Renal adenoma (a non-cancerous tumor)
- Kidney lymphoma (cancer of the lymph cells)
- Renal cyst (fluid-filled sac)
- Renal infarction (blockage of blood flow to the kidneys)
- Sarcoma (a type of cancer)
- Metastasis from tumors elsewhere in the body, such as metastatic melanoma (skin cancer that has spread)
Moreover, based on the patient’s symptoms, the following conditions must also be considered:
- Acute pyelonephritis (a serious kidney infection)
- Bladder cancer
- Chronic pyelonephritis (long-term kidney infection)
- Non-Hodgkin lymphoma (a cancer that originates in your lymphatic system)
- Adult type Wilms tumor (a rare kidney cancer that primarily affects children)
What to expect with Renal Cancer
RCC, or renal cell carcinoma, has a survival rate of about 75% over five years. This rate jumps to 93% if the disease is caught in the early stages. Stage 1 and 2 RCC have the best outcomes, with survival rates between 85-90%.
In 2012, a grading system was created by the International Society of Urological Pathology (ISUP), which was later adopted by the World Health Organization (WHO). This system is used to grade kidney cancers like RCC. The grading is done based on certain characteristics of the tumor’s nucleus. Specific factors considered include how much the tumor has spread, whether it involves the veins or adrenal gland, the severity of the cancer, whether the tumor has spread to the lymph vessels, and the amount of cancer tissue death.
Chromophobe RCC, a specific type of kidney cancer, is not graded in the ISUP system. Generally, large and aggressive tumors have a higher grade.
Together, these factors help doctors to predict how the cancer will behave and decide on the best treatment. These predictors can be grouped into three main categories: aspects related to the tumor itself, aspects related to the patient’s overall health, and results from lab tests.
They include:
– Tumor related: Stage of the cancer, size of the tumor, severity of the cancer, type of tumor, whether the tumor cells have died (necrosis), and whether the tumor has changed (sarcomatoid transformation).
– Patient-related: Whether the patient has symptoms or not, patient’s overall health condition, significant weight loss, presence of symptoms indicating other diseases (paraneoplastic syndrome), the time without spread to other parts (metastasis-free interval), and history of prior kidney surgery (nephrectomy).
– Lab tests: Elevated levels of enzymes (LDH), hypercalcemia (high calcium levels), anemia, high platelet count, and high levels of other substances in blood (ESR and CRP).
By combining all these factors, doctors can make better predictions about the cancer and choose the best treatment options.
Possible Complications When Diagnosed with Renal Cancer
Certain complications can occur with renal cell carcinoma (RCC), a type of kidney cancer.
These include:
- Direct effects of the tumor, which could lead to problems like high blood pressure, constipation, and a feeling of fullness or bloating in the stomach.
- Paraneoplastic phenomena, which are strange symptoms caused by substances the tumor produces. This could result in excess red blood cells production, high calcium levels, and non-cancerous liver involvement such as Stauffer’s syndrome. This syndrome could cause increased levels of certain enzymes and proteins in the blood, and large liver and spleen.
- Metastasis or spread of the cancer to other parts of the body. This could cause problems with lung function (if it spreads to the lungs), varicose veins (if it spreads through the veins), bony pain and spinal cord compression (if it spreads to the bones), seizures (if it spreads to the brain), and liver issues (if it spreads to the liver).
In addition, some adverse side effects might occur from targeted treatments or surgery for RCC. These might include:
- Kidney function problems
- High blood pressure
- Loss of protein in the urine
- Slow wound healing
- Tearing in the stomach or intestines
- Bleeding and formation of blood clots
- Reversible damage to white matter in the brain
- Heart function problems
- Problems with hormone production, like an underactive thyroid
