Kidney / Renal Cancer

The Function of the Kidneys and Complications Associated with Kidney Cancer

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 waste products, excess water, and toxins from the blood, forming urine. They also help regulate blood pressure, red blood cell production through erythropoietin, and maintain the body’s electrolyte balance. Damage or disease affecting the kidneys can compromise these essential tasks and lead to serious health complications.

Kidney cancer disrupts the filtration, hormone production, and fluid balance functions of the kidneys. If untreated, it may result in kidney failure, uncontrolled hypertension, bone marrow suppression, and metastasis to vital organs like the lungs, brain, and bones. Renal cancer is often asymptomatic in its early stages and is frequently discovered incidentally during imaging for unrelated conditions. Recognising risk factors and raising awareness are crucial for early diagnosis and improved treatment outcomes.

Categories Associated With Primary and Secondary Kidney Tumours

Kidney tumours are categorised as either primary (originating in the kidney) or secondary (metastatic tumours from other organs):

Primary Kidney Cancer:

This originates in the tissues of the kidney. The most common type is Renal Cell Carcinoma (RCC), accounting for about 90% of adult kidney cancers. RCC originates from the lining of the proximal renal tubules. Other subtypes include:

  • Clear Cell RCC (most common)
  • Papillary RCC
  • Chromophobe RCC
  • Collecting Duct Carcinoma
  • Renal Sarcoma
  • Wilms’ Tumour (primarily in children)

Secondary (Metastatic) Kidney Cancer:

This form of kidney cancer develops when cancers from other parts of the body (like the lung, breast, colon, or melanoma) spread to the kidney. Though less common, it usually signals advanced disease.

Common causes and risk factors include:

  • Smoking
  • Obesity
  • Hypertension
  • Chronic kidney disease
  • Genetic syndromes (e.g., Von Hippel-Lindau disease)
  • Occupational exposures (asbestos, cadmium)
  • Long-term dialysis

Signs And Symptoms of Kidney Cancer

Early-stage kidney cancer is often asymptomatic. As it progresses, the following signs may emerge:

  • Hematuria (blood in urine)
  • Flank or lower back pain
  • A palpable abdominal mass or lump
  • Unexplained weight loss
  • Persistent fatigue
  • Intermittent fever not linked to infection
  • Hypertension
  • Anaemia or erythrocytosis (abnormal red blood cell count)
  • Swelling in the legs or ankles
  • Bone pain (in advanced or metastatic disease)

Late-stage symptoms may result from tumour spread to other parts of the body.

Diagnosis of Kidney Cancer

A structured diagnostic pathway is used to confirm and stage kidney cancer:

Medical History and Physical Examination:

Assessment of symptoms, risk factors, and a physical check for abdominal or flank masses.

Laboratory Tests:

  • Urinalysis: Detects hematuria or proteinuria
  • Blood Tests: Includes complete blood count (CBC), kidney function tests (creatinine, BUN), and serum calcium levels

Imaging Studies:

  • Ultrasound: Often the first test to detect kidney masses
  • CT Scan: The gold standard for evaluating tumour size, location, and spread
  • MRI: Useful in patients with contrast allergy or evaluating blood vessels
  • Chest X-ray/PET-CT: Used to detect distant metastases

Biopsy (optional in certain cases):

Used when imaging results are inconclusive or before initiating nonsurgical therapies.

Staging:

Staging based on the TNM system helps guide treatment decisions. Bone scans and other specialised imaging may be used to assess for spread.

Best Treatment for Kidney Cancer

Treatment options vary depending on cancer type, size, location, stage, and the patient’s overall health. The main treatment strategies are:

A. Traditional Treatments

B. Advanced and Alternative Treatments

C. Traditional Treatment for Kidney Cancer

1. Surgical Procedures

  • Partial Nephrectomy (Nephron-Sparing Surgery): Recommended for small, localised tumours to preserve kidney function.
  • Radical Nephrectomy: Complete removal of the kidney along with nearby tissues and lymph nodes. Indicated for large or invasive tumours.

2. External Beam Radiation Therapy

Though not commonly used as the first line for RCC (which is radioresistant), radiation may be applied to relieve pain or control metastases (e.g., in bones or brain).

3. Systemic Chemotherapy

Traditional chemotherapy is largely ineffective for RCC. However, it may be considered in rare subtypes like collecting duct carcinoma or in pediatric Wilms’ tumour. Side effects vary based on drug type, dose, and patient tolerance.

B. Advanced Treatments for Kidney Cancer

Modern strategies offer targeted, minimally invasive, and immune-enhancing approaches:

1. Microinvasive Therapies and Surgeries

  • Cryoablation:
  • Involves freezing cancerous tissue using a cryoprobe under CT or ultrasound guidance. Recommended for patients unfit for surgery or with small renal masses.
  • Laparoscopic or Robotic Surgery: Minimally invasive methods offer quicker recovery and less blood loss.

2. Targeted Therapies

I. Tyrosine Kinase Inhibitors (TKIs):

  • Drugs like sunitinib, sorafenib, pazopanib, and axitinib target angiogenesis (tumour blood supply).
  • Often used in advanced RCC to control tumour progression.

II. mTOR Inhibitors:

  • Temsirolimus and everolimus disrupt pathways promoting cancer cell growth and metabolism.

3. Immunotherapy and Biologic Agents

Checkpoint inhibitors have revolutionised kidney cancer treatment:

  • Anti-PD-1 / PD-L1 Inhibitors: Nivolumab, Pembrolizumab
  • CTLA-4 Inhibitor: Ipilimumab
  • These therapies unleash the body’s immune system to recognise and destroy cancer cells.

4. Combination Therapies

Several frontline regimens combine immunotherapy with targeted drugs (e.g., Nivolumab + Ipilimumab or Avelumab + Axitinib), offering superior outcomes compared to monotherapies.

Prevention and Lifestyle Management

While not all kidney cancers are preventable, risk reduction strategies include:

  • Quitting smoking
  • Maintaining a healthy weight
  • Managing hypertension
  • Reducing exposure to toxic chemicals (e.g., cadmium, trichloroethylene)
  • Keeping diabetes and chronic kidney disease under control
  • Staying hydrated and following a kidney-friendly diet
  • Routine monitoring for those with genetic predispositions or familial cancer syndromes

Early detection via imaging and monitoring in high-risk individuals can prevent advanced-stage disease.

Prognosis and Survival Rates

Prognosis depends on cancer stage, type, and response to therapy. Localised RCC has a 5-year survival rate of around 93%. This decreases to 70% for regional spread and 13% for metastatic disease. Advances in immunotherapy and targeted therapy have significantly improved survival in advanced cases. Regular monitoring post-treatment is essential to detect recurrences early.

Conclusion

Kidney cancer represents a complex oncological condition with varying presentations and outcomes. The kidneys’ vital role in filtration, regulation, and hormonal balance makes cancer in this region particularly impactful on overall health. While surgical resection remains the cornerstone for localised tumours, modern advances in targeted therapy, microinvasive ablation, and immunotherapy are transforming treatment for advanced stages. Awareness, risk factor control, and early screening are vital to reduce the global burden of kidney cancer.