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Kidneys Cancer

Urology

The kidneys are a pair of bean-shaped organs on either side of the spine in the lower back. They are crucial in the body's metabolism, secreting urine to eliminate excess water, metabolic waste, and toxins. When the kidneys develop a malignant tumour, it is called kidney cancer.

There are two common types of kidney cancer based on the cellular morphology of the tumour: renal cell carcinoma and renal pelvis carcinoma. Renal cell carcinoma arises from the epithelial cells of the proximal renal tubules, with the cancer occurring in the renal cortex. On the other hand, renal pelvis carcinoma, a malignant tumour, may evolve from kidney stone infections and is typically located at the junction of the renal pelvis and the ureter. In Hong Kong, the majority of kidney cancer cases are renal cell carcinoma, while renal pelvis carcinoma is less prevalent with a lower incidence rate.

Symptoms

While kidney cancer is not a common type of cancer, one should not underestimate the threat it poses.

Due to the deep location of the kidneys within the human body, early-stage kidney cancer often does not cause any discomfort or symptoms. Therefore, many patients only discover it in the later stages. As the tumour grows or progresses, patients may experience some common symptoms:

Haematuria (Blood in Urine): One of the most common symptoms is that urine may sometimes contain blood, appearing pink, red, or brown.
Pain in the Back or Side: A tumour may lead to discomfort or pain in the kidney area, typically felt in the back or side.
Lump or Mass: A lump or mass may be felt in the abdomen, which could result from a kidney tumour.
Fatigue: Patients may feel tired or weak, possibly due to the tumour affecting the body's metabolic functions.
Fever: Sometimes, kidney cancer may cause fever, especially when the tumour becomes infected or invades adjacent tissues.
High Blood Pressure: Impaired kidney function may lead to high blood pressure.
Unexplained Weight Loss: Unexplained weight loss could occur, possibly because the tumour causes a loss of appetite or changes in metabolism.

Diagnosis

When suspecting kidney cancer, doctors typically start with blood and urine tests. Individuals with early-stage kidney cancer may exhibit a small amount of blood in routine urine tests. For patients with renal pelvis cancer, urine sample examination can reveal actual cancer cells in the urine. Blood tests check for elevated blood calcium levels, perform blood cell analysis, and measure kidney function to determine if the patient has kidney cancer initially.

When doctors suspect that a patient may have kidney cancer, the following further examinations may be conducted:

CT-Scan	Provides precise information about the tumour's size, shape, and location. It checks whether cancer has spread to nearby lymph nodes or organs and tissues outside the kidneys.
MRI	Provides precise information about the tumour's size, shape, and location. It checks whether cancer has spread to nearby lymph nodes or organs and tissues outside the kidneys.
Abdominal Ultrasound Examination	Ultrasound helps detect kidney tumours, their location, and size. It can show whether the mass is solid or fluid-filled, indicating the presence of kidney swelling.
X-ray Examination	When a patient is diagnosed with kidney cancer, doctors may conduct chest X-rays and a full-body bone scan to observe whether the cancer has metastasized to the lungs or bones.
PET CT	It determine whether malignant tumours have spread to lymph nodes, lungs, liver, or bones.
Kidney Biopsy	When the above imaging tests are not clear enough, and surgery is not feasible, a biopsy may be performed to obtain a small tissue sample from the potentially cancerous site. It helps determine the tumour grade of kidney cancer and confirm whether the patient has kidney cancer.

Staging

Doctors will use the above examinations to determine the stage of kidney cancer and decide on the course of treatment. Renal cell carcinoma can be divided into the following four steps:

Stage I	The tumour has a diameter of no more than 7 cm, and its extent is still within the cortex, meaning it is only within the kidney.
Stage II	The tumour has a diameter exceeding 7 cm, invading the outer periphery of the cortex. However, the cancer is still confined to the kidney.
Stage III	The primary tumour can be of any size, outside the kidney, affecting the renal vein or vena cava, and has spread to nearby lymph nodes.
Stage IV	The primary tumour can be of any size, and it may have grown outside the kidney and possibly to the adrenal glands at the top of the kidney. It has also spread to distant lymph nodes or other organs.

Treatments

According to the staging of kidney cancer, doctors will choose the most appropriate treatment for patients. In general, surgical intervention is the primary treatment for most kidney cancers. For patients with stages I to III kidney cancer, doctors will perform surgery based on the location of the tumour to remove either the entire kidney or perform a partial nephrectomy. The surrounding fat tissue, the adrenal gland, and nearby lymph nodes may also be removed depending on the situation. Studies suggest that the effectiveness of total and partial nephrectomy is roughly similar, with the latter helping patients retain more kidney function. In addition to traditional open surgery, many doctors perform minimally invasive partial nephrectomies using laparoscopy or robotic-assisted techniques.

For early-stage kidney cancer, the following invasive treatment options are also available:

Cryotherapy
- Uses ultrasound or other imaging methods to guide a special needle through the skin into the kidney tumour.
- The needle delivers cold gas to freeze and destroy malignant cells.
Radiofrequency Ablation (RFA)
- Similar to cryotherapy, it uses ultrasound or other imaging methods to guide a probe through the skin into the kidney tumour.
- Electric current passes through the probe, heating or burning the cells to cause cell death.
Embolization
- Involves blocking the blood supply to cancer cells by embolizing arterial blood vessels to shrink the tumour.

Facing stage IV kidney cancer, where cancer cells have already spread to other parts of the body, doctors will use various methods post-surgery to control or alleviate symptoms of kidney cancer that have spread. Targeted therapy is a primary approach, using drugs to interrupt blood flow and nutrient supply to cancer cells, inhibiting tumour growth and spread. Immunotherapy may also enhance the patient's immune response to cancer cells by using interferon-α and interleukin-2 to resist the cancer cells.

Other methods include radiation therapy, which uses high-energy beams to kill cancer cells and chemotherapy. Although radiation therapy may not significantly cure kidney cancer, it can alleviate symptoms and relieve tumour-induced pain. Chemotherapy involves using drugs to kill cancer cells. Still, it is generally considered less effective for kidney cancer cells, and the associated side effects, such as hair loss, mouth sores, loss of appetite, nausea, and vomiting, can be more pronounced.

The occurrence of kidney cancer is influenced by various risk factors. Here are some factors that may contribute to the development of kidney cancer:

Smoking: There is an association between smoking and kidney cancer, as the chemicals in tobacco may have harmful effects on the kidneys.
High Blood Pressure: Long-term hypertension may increase the risk of developing kidney cancer.
Genetic Factors: Individuals with a family history of kidney cancer may be more susceptible, suggesting a possible role of genetics in the development of kidney cancer.
Hereditary Kidney Cancer Syndromes: Some rare genetic conditions, such as von Hippel-Lindau (VHL) syndrome and Hereditary Leiomyomatosis, may elevate the risk of kidney cancer.
Age: Age is a risk factor for kidney cancer, with a higher prevalence typically seen in individuals aged 60 and above.
Gender: Observations indicate that males are more prone to kidney cancer than females.
Obesity: Excessive weight is a potential risk factor, and there is some level of association between obesity and the occurrence of kidney cancer.
Kidney Diseases and Cysts: Certain kidney diseases and cysts may increase the risk of developing kidney cancer.
Occupational Exposures: Exposure to specific chemicals or substances in certain occupational environments, such as certain organic solvents and heavy metals, may be related to kidney cancer.
Long-term Kidney Dialysis: Individuals undergoing long-term kidney dialysis treatment may face an increased risk of kidney cancer.