Kidney Cancer

The number of kidney cancer cases has been increasing over the past decade. According to the Hong Kong Cancer Registry, a total of 586 new kidney and other urinary organ cancers were diagnosed in male in 2021, ranking it as the 7th most common cancer type among males. In Hong Kong, there are now 17.3 cases per 100,000 male populations of kidney and other urinary organ cancer.  

According to the American Cancer Society, the 5-year survival rate for early-stage kidney cancer is around 93%. However, the public has relatively little awareness of kidney cancer, and the kidneys are located deep in the abdomen and protected by the rib cage, making it difficult to be detected. As a result, when the patients feel discomfort and seek for medical advice, the disease may already be in the mid or advanced stage, and even spread to other parts of the body. 

What is kidney cancer?  

The kidneys are a pair of bean-shaped organs located on the side of the lower back. They are part of the urinary system and an important metabolic organ in the body. The kidneys are responsible for filtering out excess waste and toxins in the blood, while absorbing useful minerals back into the body. Nitrogenous waste and other toxins are eliminated from the body in the form of urine. Kidney cancer occurs when abnormal cells in the kidneys grow out of control and form a tumour. 

The exact cause of kidney cancer is unclear. Risk factors of kidney cancer include  

• Smoking 
• Overweight (body mass index over 30)  
• Hereditary factors 
  • Kidney cancer may be hereditary. Those with a family history of kidney cancer have a higher risk of developing it. 
  • Family members who have had kidney cancer, von Hippel-Lindau disease and tuberous sclerosis complex also have increased risk.  
• Chronic kidney failure or long-term dialysis
  • Patients having renal dialysis have a higher risk of kidney cancer.
• Working in a high-risk environment 
  • Patients working with heavy metals (including cadmium), trichloroethylene, asbestos, petroleum, and other chemicals have a higher risk.
• Regular use of pain-relieving drug phenacetin 

Early symptoms of kidney cancer are often not easily noticeable. Many patients are therefore diagnosed at mid/late stage. The followings are the more common symptoms of kidney cancer:  

• Hematuria
  • Hematuria, or blood in the urine, is one of the most common symptoms of kidney cancer. You may pass urine with blood, but there is no pain. 
• Flank/back pain
  • Due to compression by the tumour, you may experience abdominal and back pain. 
  • You may also notice a lump at the flank/back when the tumour grows larger. However, if the mass is hidden under the ribs or muscles, you may miss it. 
• Other symptoms include poor appetite, fatigue, fever, anemia, etc. 

Initial examination  

• Blood test 
• Complete blood count 
• Liver/ renal function test
• Calcium and LDH blood tests 

Imaging tests  

• Ultrasound
  • Abdominal ultrasound is commonly used to locate the tumour and check for the size.
• CT scan 
  • Abdominal and pelvic computed tomography (CT) imaging is used to check for the size, location, any invasion to the vessels and any distant metastasis. 
• Histological Diagnosis
• Surgery
  • Image-guided biopsy
    • Can be used if upfront resection is not considered. 

Stage I:  

• Tumour size is less than 7cm and is confined to the kidney without spread to lymph nodes or nearby organs (T1, N0, M0).  

Stage II:  

• Tumour size is greater than 7cm and is confined to the kidney without spread to lymph nodes or nearby organs (T2, N0, M0).  

Stage III: Any of the following conditions: 

• Any size tumour within the kidney with spread to nearby lymph nodes but not to nearby organs (T1 or T2, N1, M0).  
• Cancer cells have spread to the main vein of the kidney or to the surrounding tissues but not to other organs (T3, any N, M0).  

Stage IV: Any of the following conditions: 

• Tumour has spread beyond the Gerota's fascia of the kidney to the surrounding tissue and to the adrenal gland and lymph nodes on the same side, but not to other organs (T4, any N, M0). 
• Cancer cells have spread to other distant organs such as the lungs, bone, or brain (any T, any N, M1). 

Doctors will consider the following factors when designing a treatment plan: 

• Cancer staging  
• Tumour location  
• Patient's overall health status 

Partial nephrectomy 

• This is a common surgery for kidney cancer smaller than 4cm. 
• Doctor will remove the tumour but leave as many normal tissues as possible to keep the kidney working. 

Radical nephrectomy 

• Doctor will remove the whole kidney and the surrounding tissue during the surgery. Lymph nodes close to the kidney are also removed. 

Tumour Ablation 

• Tumour ablation utilizes extreme temperatures to eliminate small tumours. It is an alternative for patients who have a small tumour and are either not physically capable of undergoing surgery or prefer not to do so. 
• Cryotherapy uses liquid nitrogen to freeze the tumour. 
• Radiofrequency ablation (RFA) uses an electric current to produce high temperatures to destroy the tumour. 

Immunotherapy 

Immunotherapy, also called immune checkpoint inhibitor, stimulates the natural immune system in the body to combat cancer cells. Immunotherapy is commonly used for advanced or metastatic kidney cancer that has spread to other areas of the body.  

The following immune checkpoint inhibitors are often used in treating kidney cancer: 

• Nivolumab
• Ipilimumab
• Pembrolizumab  
• Avelumab 

Targeted Therapy  

Targeted therapy uses tyrosine kinase inhibitors (TKI) to treat advanced and metastatic kidney cancer. It stops the growth and division of cancer cells. The commonly used targeted therapies include: 

• Sunitinib 
• Pazopanib 
• Cabozantinib 
• Axitinib 

Side effects of targeted therapies may include tiredness, nausea, sore mouth, skin rashes, and diarrhoea.  

You can consult your doctor for other side effects. 

There is no definitive method to entirely prevent kidney cancer. Nevertheless, maintaining a healthy lifestyle and eating habits are essential: 

• Quit smoking. 
• Manage blood pressure. 
• Maintain a healthy body weight. 
• Limit the intake of animal fat and meat (especially red meat). 
• Have a greater proportion of fresh vegetables and fruits in the diet. 

Hong Kong Cancer Registry (HKCaR)

Hong Kong Society of Uro-oncology

Macmillan Cancer Support: Kidney Cancer

Macmillan Cancer Support: Targed therapies

Special thanks to Ms. Emina Cheung, and Dr. Steven Wai-Kwan Siu, Department of Clinical Oncology, Queen Mary Hospital for authoring and editing this article. 

Last updated on 13th May, 2024.