Kidney Cancer: Symptoms, Causes & Treatment Options

What Is Kidney Cancer?

Kidney cancer, also known as renal cell carcinoma (RCC), is a malignant tumor that originates in the kidney's tubular cells. It accounts for approximately 3% of all adult cancers and is the most common type of kidney malignancy in adults, representing about 90% of all kidney cancers.

The kidneys are two bean-shaped organs located on either side of the spine, just below the rib cage. Their primary function is to filter blood, remove waste products, regulate fluid balance, and produce hormones that control blood pressure and red blood cell production. When cancer develops in the kidney, it typically begins in the lining of tiny tubes (tubules) within the kidney that filter the blood.

Kidney cancer usually develops as a single tumor in one kidney, although having tumors in both kidneys simultaneously can occur but is uncommon. When both kidneys are affected, the disease is often hereditary. The cancer cells can potentially spread (metastasize) to other parts of the body, most commonly to the lungs, bones, liver, or brain. However, when detected early, before the cancer has spread, the outcomes are generally excellent.

Renal cell carcinoma is the most common type of kidney cancer in adults, but several other types exist. Clear cell RCC is the most prevalent subtype, accounting for about 70-80% of cases. Other subtypes include papillary RCC, chromophobe RCC, and collecting duct carcinoma, each with different characteristics and prognoses. Understanding the specific subtype is important for determining the most effective treatment approach.

How Does Kidney Cancer Develop?

Cancer develops when cells undergo genetic mutations that cause them to grow and divide uncontrollably. In kidney cancer, these mutations occur in the cells lining the small tubes in the kidney. The exact triggers for these mutations are not always clear, but certain risk factors significantly increase the likelihood of developing the disease.

The process typically begins with a single abnormal cell that accumulates additional genetic changes over time. As these abnormal cells multiply, they form a mass or tumor. In the early stages, the tumor is confined to the kidney. However, as it grows, cancer cells may invade surrounding tissues or break away and travel through the bloodstream or lymphatic system to form new tumors in distant organs.

Wilms Tumor in Children

While kidney cancer primarily affects adults, children can develop a different type of kidney cancer called Wilms tumor (nephroblastoma). This is the most common kidney cancer in children, typically occurring between ages 3 and 4. Wilms tumor has different characteristics, treatment approaches, and outcomes compared to adult kidney cancer. Fortunately, childhood kidney cancers are rare, and Wilms tumor generally has an excellent prognosis with appropriate treatment.

What Are the Symptoms of Kidney Cancer?

Early kidney cancer typically causes no symptoms and is often discovered incidentally during imaging tests. When symptoms do occur, they may include blood in the urine (hematuria), persistent pain in the side or lower back, a palpable mass in the abdomen, unexplained weight loss, fatigue, and intermittent fever.

One of the challenging aspects of kidney cancer is that it often grows silently in its early stages without causing any noticeable symptoms. This is why the majority of kidney cancers today are discovered incidentally when patients undergo CT scans, MRIs, or ultrasounds for unrelated medical conditions. This "incidental detection" has actually improved overall survival rates because cancers are being found at earlier, more treatable stages.

When kidney cancer does cause symptoms, they are often vague and can be mistaken for other conditions. The classic triad of symptoms—blood in the urine, flank pain, and a palpable abdominal mass—actually occurs in only about 10% of patients and usually indicates more advanced disease. Understanding the various symptoms can help individuals recognize when to seek medical evaluation.

The symptoms of kidney cancer can be categorized into local symptoms (caused by the tumor in the kidney), systemic symptoms (affecting the whole body), and symptoms from metastasis (if the cancer has spread). Local symptoms result directly from the growing tumor, while systemic symptoms occur because of substances produced by the tumor or the body's response to the cancer.

Blood in the Urine (Hematuria)

Blood in the urine is one of the most significant warning signs of kidney cancer. The blood may be visible to the naked eye (gross hematuria), making the urine appear pink, red, or cola-colored. Alternatively, the blood may only be detectable through microscopic examination (microscopic hematuria) during a routine urinalysis. Hematuria from kidney cancer is typically painless and may be intermittent, appearing and then disappearing for periods of time.

It's important to note that blood in the urine has many possible causes, including urinary tract infections, kidney stones, benign prostate enlargement, and bladder problems. However, any instance of visible blood in the urine should be promptly evaluated by a healthcare provider to rule out serious conditions including cancer.

Pain and Discomfort

Pain associated with kidney cancer is typically located in the side or lower back, on the same side as the affected kidney. The pain is often described as a dull ache that persists over time, rather than sharp or cramping pain. As the tumor grows, it can stretch the kidney capsule or press on nearby nerves, causing discomfort. Pain that doesn't go away with rest or over-the-counter pain medications warrants medical evaluation.

Other Common Symptoms

• A lump or mass in the abdomen or side: As the tumor grows, it may become large enough to feel during a physical examination or even by the patient themselves.
• Unexplained weight loss: Losing weight without trying, particularly 10 pounds or more, can be a sign of cancer.
• Fatigue: Persistent tiredness that doesn't improve with rest is common in many cancers, including kidney cancer.
• Intermittent fever: Fever not caused by infection can occur in kidney cancer patients.
• Loss of appetite: A decreased interest in food may accompany the disease.
• Anemia: The kidneys produce erythropoietin, a hormone that stimulates red blood cell production. Kidney cancer can affect this function.

What Causes Kidney Cancer?

The exact cause of kidney cancer is not fully understood, but several risk factors significantly increase the likelihood of developing the disease. These include smoking (responsible for about one-third of cases), obesity, high blood pressure, chronic kidney disease, and certain inherited genetic conditions. Most kidney cancers occur sporadically without a clear hereditary component.

Kidney cancer develops when cells in the kidney undergo genetic mutations that cause them to grow and divide abnormally. These mutations can be caused by various factors, some of which are modifiable through lifestyle changes, while others are beyond our control. Understanding these risk factors can help individuals make informed decisions about their health and potentially reduce their risk.

Research has identified several key risk factors that increase the likelihood of developing kidney cancer. While having one or more of these risk factors doesn't mean someone will definitely develop the disease, awareness of these factors can guide prevention strategies and inform decisions about screening in high-risk individuals.

Smoking

Smoking is the most significant modifiable risk factor for kidney cancer, accounting for approximately one-third of all cases. The risk increases with the number of cigarettes smoked and the duration of smoking. Smokers have roughly double the risk of developing kidney cancer compared to non-smokers. The carcinogens in tobacco smoke are filtered through the kidneys and can damage the DNA of kidney cells, potentially leading to cancer.

The good news is that quitting smoking reduces the risk over time. Former smokers have a lower risk than current smokers, and the risk continues to decrease the longer a person remains smoke-free. This demonstrates that it's never too late to benefit from quitting.

Obesity

Obesity is strongly associated with an increased risk of kidney cancer. Studies show that obese individuals (BMI of 30 or higher) have approximately twice the risk of developing kidney cancer compared to those at a healthy weight. The mechanisms behind this association are complex but likely involve hormonal changes, chronic inflammation, and metabolic alterations that promote cancer development.

Maintaining a healthy weight through a balanced diet and regular physical activity not only reduces kidney cancer risk but also lowers the risk of many other cancers and chronic diseases. Even modest weight loss in overweight individuals can provide health benefits.

High Blood Pressure

Hypertension (high blood pressure) has been consistently linked to an increased risk of kidney cancer, independent of other factors. The relationship between high blood pressure and kidney cancer is complex, as it's unclear whether the hypertension itself or the medications used to treat it play a role. However, controlling blood pressure through lifestyle modifications and medication when necessary is important for overall kidney health.

Hereditary and Genetic Factors

While most kidney cancers occur sporadically, approximately 5% are hereditary. Several genetic syndromes increase the risk of kidney cancer:

• Von Hippel-Lindau (VHL) disease: A rare genetic condition that significantly increases the risk of kidney cancer, particularly clear cell RCC. People with VHL mutations may develop multiple tumors in both kidneys.
• Hereditary papillary renal cell carcinoma: Caused by mutations in the MET gene, leading to an increased risk of papillary kidney cancer.
• Birt-Hogg-Dubé syndrome: Associated with chromophobe and hybrid kidney tumors.
• Hereditary leiomyomatosis and renal cell cancer (HLRCC): Linked to aggressive papillary type 2 kidney cancer.

Individuals with a family history of kidney cancer, especially those diagnosed at a young age or with cancer in both kidneys, may benefit from genetic counseling and testing to assess their hereditary risk.

Other Risk Factors

• Chronic kidney disease: Long-term kidney disease and dialysis increase kidney cancer risk.
• Workplace exposures: Certain chemicals such as asbestos, cadmium, and some herbicides have been linked to increased risk.
• Gender: Men are about twice as likely as women to develop kidney cancer.
• Age: Risk increases with age, with most cases diagnosed between 60-70 years.

When Should You See a Doctor?

Contact your healthcare provider if you experience blood in your urine, persistent pain in your side or lower back, unexplained weight loss, fatigue that doesn't improve with rest, or a lump in your abdomen. Any visible blood in the urine should be evaluated promptly, as should symptoms that persist for more than a few weeks.

Because kidney cancer often causes no symptoms in its early stages, many cases are discovered during routine medical examinations or imaging tests performed for other reasons. However, certain symptoms should prompt a visit to your healthcare provider for evaluation. While these symptoms may be caused by conditions other than cancer, it's important to rule out serious conditions.

You should contact your healthcare provider if you notice any of the following symptoms that persist for more than two weeks or are particularly severe:

• Blood in your urine (even if it appears only once)
• Persistent pain in your side, back, or abdomen
• A lump or mass that you can feel in your abdomen or side
• Unexplained weight loss
• Persistent fatigue
• Fever that comes and goes without infection
• Swelling in your ankles or legs

How Is Kidney Cancer Diagnosed?

Kidney cancer is diagnosed through a combination of physical examination, blood and urine tests, and imaging studies. CT scan with contrast is the gold standard for detecting and characterizing kidney tumors. MRI and ultrasound may also be used. A biopsy may be performed in some cases to confirm the diagnosis, though surgery is often performed based on imaging alone when cancer is strongly suspected.

The diagnostic process for kidney cancer typically begins when a patient reports symptoms or when a tumor is discovered incidentally during imaging for another condition. A systematic approach helps determine the nature of the kidney mass, whether it's cancerous, and if so, whether it has spread to other parts of the body.

The diagnostic workup serves multiple purposes: confirming the diagnosis, determining the stage and grade of the cancer, assessing overall kidney function, and gathering information needed to plan the most appropriate treatment. This comprehensive evaluation involves several types of tests and examinations.

Medical History and Physical Examination

The initial evaluation includes a thorough medical history, where your doctor will ask about symptoms, risk factors (such as smoking, obesity, and family history), and overall health. During the physical examination, the doctor will feel your abdomen and sides for any lumps or masses, check blood pressure, and assess overall health status.

Blood and Urine Tests

Laboratory tests provide important information about kidney function and overall health:

• Complete blood count (CBC): Checks for anemia (common in kidney cancer) and overall blood cell counts
• Blood chemistry tests: Assess kidney function through creatinine and blood urea nitrogen (BUN) levels
• Liver function tests: Important for staging and treatment planning
• Urinalysis: Checks for blood and other abnormalities in the urine
• Calcium levels: May be elevated in some kidney cancers

Imaging Studies

Imaging is crucial for diagnosing kidney cancer and determining its extent:

• CT scan (computed tomography): The gold standard for evaluating kidney masses. A CT scan with contrast can characterize the tumor, assess its size and location, and detect spread to lymph nodes or other organs.
• MRI (magnetic resonance imaging): Particularly useful for patients who cannot receive CT contrast or when better characterization of the tumor is needed. MRI provides excellent detail of soft tissue structures.
• Ultrasound: Often the first imaging test used and can distinguish solid masses from fluid-filled cysts. However, CT or MRI is usually needed for further evaluation.
• Chest X-ray or chest CT: To check for spread to the lungs
• Bone scan: If there's concern about spread to bones
• PET scan: May be used in certain situations to detect spread

Biopsy

Unlike many other cancers, kidney cancer is often diagnosed and treated based on imaging alone, without a biopsy. This is because imaging can usually characterize kidney masses with high accuracy, and there's a small risk of spreading cancer cells during the biopsy procedure.

However, a biopsy may be recommended in certain situations:

• When the imaging findings are unclear or atypical
• Before starting systemic therapy for metastatic disease
• When active surveillance is being considered for small tumors
• To confirm recurrence in previously treated patients

What Are the Stages of Kidney Cancer?

Kidney cancer is staged from I to IV based on tumor size, local invasion, lymph node involvement, and distant spread. Stage I tumors are 7 cm or smaller and confined to the kidney. Stage II tumors are larger than 7 cm but still confined. Stage III involves local spread to nearby tissues or lymph nodes. Stage IV indicates spread to distant organs such as lungs, bones, or brain.

Staging is a critical part of the diagnostic process as it determines prognosis and guides treatment decisions. The staging system most commonly used for kidney cancer is the TNM system, which considers the size and extent of the primary Tumor (T), whether cancer has spread to nearby lymph Nodes (N), and whether there are distant Metastases (M).

Understanding the stage of your cancer helps you and your healthcare team discuss treatment options and expected outcomes. Early-stage kidney cancer (Stage I-II) generally has excellent outcomes with surgery, while advanced stages may require a combination of treatments.

How Is Kidney Cancer Treated?

Treatment for kidney cancer depends on the stage and type of cancer, overall health, and patient preferences. Surgery (partial or radical nephrectomy) is the primary treatment for localized disease. For metastatic cancer, treatment options include targeted therapy, immunotherapy, or a combination. Active surveillance may be appropriate for small, slow-growing tumors in certain patients. Ablation therapy using heat or cold is an option for some small tumors.

The treatment of kidney cancer has evolved significantly over the past two decades, with the introduction of targeted therapies and immunotherapy dramatically improving outcomes for patients with advanced disease. Treatment decisions are made by a multidisciplinary team that may include urologists, oncologists, radiologists, and other specialists, working together to develop an individualized treatment plan.

The goals of treatment vary depending on the stage of the cancer. For localized disease, the goal is cure through complete removal of the tumor. For metastatic disease, treatment aims to control the cancer, slow its progression, relieve symptoms, and extend survival while maintaining quality of life.

Surgery for Localized Kidney Cancer

Surgery is the primary treatment for kidney cancer that has not spread beyond the kidney. The type of surgery depends on the size and location of the tumor, as well as the function of both kidneys:

• Partial nephrectomy (nephron-sparing surgery): Removes only the tumor and a small margin of healthy tissue, preserving most of the kidney. This is preferred for smaller tumors (typically less than 4-7 cm) and when preserving kidney function is important.
• Radical nephrectomy: Removes the entire affected kidney, often along with the adrenal gland and surrounding fatty tissue. This is typically used for larger tumors or when the cancer involves the central part of the kidney.

Both types of surgery can often be performed using minimally invasive techniques (laparoscopic or robotic-assisted surgery), which typically result in shorter hospital stays, less pain, and faster recovery compared to open surgery. The choice between partial and radical nephrectomy depends on tumor characteristics and patient factors.

After surgery to remove one kidney, the remaining kidney can usually compensate and provide adequate kidney function for normal daily activities. Most people can live completely normal lives with one kidney, though they should take care to avoid medications that could harm their remaining kidney and should have regular follow-up monitoring.

Ablation Therapy

For patients who are not good candidates for surgery due to other health conditions, or for small tumors, ablation therapy may be an option. This involves destroying the tumor using extreme temperatures:

• Cryoablation: Uses extreme cold to freeze and destroy cancer cells
• Radiofrequency ablation (RFA): Uses high-energy radio waves to heat and destroy cancer cells

These procedures are typically performed by inserting a needle through the skin and into the tumor, guided by ultrasound or CT imaging. While ablation has lower long-term success rates than surgery, it may be appropriate for selected patients with small tumors.

Active Surveillance

For small kidney tumors (typically less than 3-4 cm), especially in elderly patients or those with significant other health conditions, active surveillance may be an option. This involves regular imaging to monitor the tumor for growth, with treatment initiated if the tumor shows significant growth. Many small kidney tumors grow slowly and may never cause problems during a patient's lifetime.

Treatment for Advanced and Metastatic Kidney Cancer

When kidney cancer has spread beyond the kidney, systemic treatments are used. The treatment landscape for metastatic kidney cancer has been transformed by the development of targeted therapies and immunotherapy:

Targeted Therapy: These drugs target specific molecules involved in cancer cell growth and survival. Common targeted therapies for kidney cancer include:

• Tyrosine kinase inhibitors (TKIs) such as sunitinib, pazopanib, cabozantinib, and lenvatinib
• mTOR inhibitors such as everolimus and temsirolimus

Immunotherapy: Immune checkpoint inhibitors help the immune system recognize and attack cancer cells. These have become a cornerstone of treatment for advanced kidney cancer:

• PD-1/PD-L1 inhibitors such as nivolumab and pembrolizumab
• CTLA-4 inhibitors such as ipilimumab

Combination Therapy: Current guidelines often recommend combinations of immunotherapy drugs or immunotherapy combined with targeted therapy as first-line treatment for metastatic kidney cancer, as these combinations have shown improved outcomes compared to single-agent therapy.

Traditional chemotherapy is generally not effective for kidney cancer, which is why targeted therapy and immunotherapy are the mainstays of systemic treatment. Radiation therapy may be used to treat specific metastases, particularly those in the brain or bones, but is not typically used as a primary treatment.

How Does Kidney Cancer Affect Daily Life?

After treatment for kidney cancer, most patients can return to normal activities. Those who have had one kidney removed can live completely normal lives, as the remaining kidney compensates. Regular follow-up appointments are essential to monitor for recurrence. Patients may experience fatigue, emotional challenges, and concerns about recurrence, but support resources are available to help.

The impact of kidney cancer on daily life varies significantly depending on the stage at diagnosis, the type of treatment received, and individual factors. Many people with early-stage kidney cancer who are treated with surgery return to their normal activities within weeks to months after recovery. Understanding what to expect can help patients and their families prepare for life after diagnosis.

Living with One Kidney

If you've had one kidney removed (nephrectomy), your remaining kidney can usually function well enough to maintain normal health. The body is remarkably adaptable, and the remaining kidney typically increases its function to compensate for the loss. Most people with one kidney can:

• Return to normal work and daily activities
• Exercise and participate in most sports
• Eat a normal diet (though limiting salt and maintaining healthy habits is recommended)
• Live a normal lifespan

However, certain precautions are important: avoiding medications that can harm the kidneys (such as high doses of NSAIDs), staying well-hydrated, controlling blood pressure, and having regular check-ups to monitor kidney function.

Follow-Up Care

After treatment for kidney cancer, regular follow-up is essential to monitor for recurrence and manage any long-term effects of treatment. The follow-up schedule typically includes:

• Physical examinations
• Blood tests to check kidney function and other markers
• Imaging studies (CT scans, MRIs) at regular intervals

The frequency of follow-up visits depends on the stage of the original cancer and the risk of recurrence. Generally, patients are seen more frequently in the first few years and less often as time passes without recurrence. For many patients, follow-up continues for at least five years, though some may be monitored longer.

Chronic Kidney Disease Risk

Some patients who have had kidney cancer treatment may develop chronic kidney disease over time, particularly those who had part or all of one kidney removed. Regular monitoring of kidney function helps detect any decline early, allowing for interventions to slow progression and protect the remaining kidney function.

Emotional Well-being

A cancer diagnosis can have significant psychological impacts. Many patients experience a range of emotions including fear, anxiety, depression, and uncertainty about the future. It's important to acknowledge these feelings and seek support when needed. Resources that can help include:

• Support groups for cancer patients and survivors
• Counseling or therapy
• Talking with other patients who have been through similar experiences
• Open communication with healthcare providers about concerns

Can Kidney Cancer Be Prevented?

While kidney cancer cannot always be prevented, you can reduce your risk by avoiding tobacco, maintaining a healthy weight, controlling blood pressure, staying physically active, and eating a balanced diet rich in fruits and vegetables. Avoiding workplace exposure to harmful chemicals and staying well-hydrated may also help reduce risk.

Because the exact causes of kidney cancer are not fully understood, it's not possible to prevent all cases. However, since several modifiable risk factors have been identified, there are meaningful steps you can take to reduce your risk:

• Don't smoke: If you smoke, quitting is the single most important thing you can do to reduce your kidney cancer risk. Smoking accounts for about one-third of kidney cancer cases.
• Maintain a healthy weight: Obesity significantly increases kidney cancer risk. Even modest weight loss can provide health benefits.
• Control blood pressure: High blood pressure is associated with increased kidney cancer risk. Work with your healthcare provider to keep your blood pressure in a healthy range.
• Stay physically active: Regular exercise helps maintain a healthy weight and may independently reduce cancer risk.
• Eat a healthy diet: A diet rich in fruits and vegetables may help protect against kidney cancer.
• Avoid harmful workplace exposures: If you work with chemicals such as cadmium or certain herbicides, follow safety guidelines to minimize exposure.
• Stay hydrated: Adequate fluid intake keeps the kidneys functioning well and may help reduce risk.

For individuals with hereditary syndromes that increase kidney cancer risk (such as von Hippel-Lindau disease), genetic counseling and regular screening can help detect cancers at an early, more treatable stage.