Know yourself, know your enemy, and you will never be defeated
Overview of Hong Kong
The kidneys are a pair of bean-shaped organs on either side of the spine in the lower back. They play a vital role in metabolism by producing urine to eliminate excess water, waste products, and toxins from the body. The kidneys also have essential secretory functions, such as producing renin to help control blood pressure and erythropoietin to ensure adequate red blood cell production.
When a malignant tumour develops in the kidneys, it is called kidney cancer. The two most common types of kidney cancer, classified by the type of tumour cells, are renal cell carcinoma and transitional cell carcinoma (also known as renal pelvis cancer). Renal cell carcinoma arises from the epithelial cells of the proximal renal tubules and typically occurs in the renal cortex. In contrast, transitional cell carcinoma can develop from infections related to kidney stones and is generally located at the junction of the renal pelvis and ureter. Most kidney cancer patients in Hong Kong are diagnosed with renal cell carcinoma, with transitional cell carcinoma being less common and having a lower incidence.
Awareness of kidney cancer among the Hong Kong population is limited. Although it is not one of the most common cancers in the region, the number of kidney cancer cases has been on the rise over the past decade. Data from the Hong Kong Cancer Registry shows that between 2009 and 2018, the number of kidney cancer cases increased by over 50%. Approximately 4.4 individuals per 100,000 people in Hong Kong are affected by this disease. According to the Hospital Authority’s cancer statistics overview for 2018, the age-standardised incidence rate of kidney cancer has also shown a significant upward trend over the past decade, with an average annual percentage increase of 1.6% for women and 3.1% for men. According to the American Cancer Society, the 5-year survival rate for early-stage kidney cancer can reach 93%. However, most patients seek medical attention only when they experience discomfort, often finding that the cancer has progressed to an advanced stage, spreading beyond the kidneys to other parts of the body, which results in a survival rate dropping to 13%.
Anyone can develop kidney cancer, but generally, the risk increases with age. In Hong Kong, kidney cancer primarily affects older individuals, with most new cases occurring in those over 45 years old, peaking between the ages of 65 and 75. This age group has a new case rate 14 times higher than individuals aged 0 to 44. Kidney cancer patients are generally more likely to be male.
As with most cancers, the exact causes of kidney cancer remain unclear. However, several factors may increase the risk of developing kidney cancer, including:
In addition to these factors, older age, high blood pressure, obesity, long-term use of painkillers, and substance abuse further increase the risk of kidney cancer. Most cases of renal cell carcinoma are sporadic, with no identifiable risk factors.
Symptoms of Kidney Cancer
Although kidney cancer is not common, it should not be underestimated due to the threats it poses. As mentioned earlier, the kidneys are located deep within the body, and even when tumours develop, they may not cause discomfort. Therefore, early-stage kidney cancer typically does not present any signs or symptoms. Many patients discover their condition only when it has progressed to an advanced stage. Some patients may exhibit more typical symptoms, including blood in the urine, back pain, pain in the side or lower back, and a lump. As the tumour grows, some patients may experience loss of appetite, fatigue, fever, and anaemia.
Common Diagnostic Methods
If kidney cancer is suspected, doctors will first conduct blood and urine tests. Early-stage kidney cancer may be indicated by traces of blood found during routine urine tests. If a patient has transitional cell carcinoma, urine sample tests can reveal actual cancer cells. Blood tests can check calcium levels, analyse blood cells, and assess kidney function to help determine if kidney cancer is present.
When the doctor suspects the patient may have kidney cancer, further tests are typically conducted, including:
Doctors may also use angiography as part of the CT or MRI scan to assist in diagnosing kidney cancer.
Using these examinations, doctors will determine the stage of kidney cancer and decide on the treatment approach. Renal cell carcinoma can be classified into four stages:
| Stage | Description |
| I | The tumour diameter does not exceed 7 cm and is confined to the cortex, remaining within the kidney. |
| II | The tumour diameter exceeds 7 cm and invades the outer cortex, but remains confined to the kidney. |
| III | The primary tumour can be of any size and may extend beyond the kidney, affecting the renal vein or inferior vena cava. It has spread to nearby lymph nodes. |
| IV | The primary tumour can be of any size and may have grown outside the kidney, possibly invading the adrenal gland above the kidney, and may have spread to distant lymph nodes or other organs. |
Primary Treatment Methods
Based on the stage of kidney cancer, doctors will choose the most appropriate treatment method. Generally, surgical intervention is the primary treatment for most kidney cancers. For patients with stage I to III kidney cancer, surgery is performed to remove either the entire kidney or a portion of it. It may also involve removing surrounding fatty tissue, the adrenal gland, and nearby lymph nodes as necessary. Studies have shown that radical and partial nephrectomy are similarly effective, with the latter preserving more kidney function. In addition to traditional open surgery, many doctors perform minimally invasive partial nephrectomy using laparoscopic or robotic techniques.
In addition to surgical resection, early-stage kidney cancer can also be treated through the following minimally invasive techniques:
For stage IV kidney cancer, where cancer cells have metastasised to other parts of the body, doctors will tailor post-surgical treatments to control or alleviate symptoms in areas where the cancer has spread, although the effectiveness is limited. Targeted therapy is primarily used to treat advanced kidney cancer by disrupting the blood supply to the cancer cells, inhibiting tumour growth and spread. Doctors may also employ immunotherapy to enhance the patient’s immune response against cancer cells. Specific proteins produced by cancer cells can help them evade the immune system, but treatments like interferon-alpha and interleukin-2 leverage the body’s immune system to combat cancer cells. Common side effects of immunotherapy include fatigue, diarrhoea, and rashes.
Other methods include radiation therapy, which uses high-energy beams to kill cancer cells, and chemotherapy. Although radiation therapy is not particularly effective for kidney cancer, it can alleviate symptoms and reduce pain caused by tumours. Chemotherapy can kill cancer cells, but kidney cancer cells generally respond poorly to chemotherapy, which may produce significant side effects, such as hair loss, mouth sores, loss of appetite, nausea, and vomiting.
Healthy Living
After completing treatment, kidney cancer patients need to undergo regular follow-up examinations, including imaging and blood tests, to monitor for any recurrence of cancer. As previously mentioned, smoking is associated with an increased risk of kidney cancer; therefore, kidney cancer survivors must quit smoking to reduce the risk of recurrence. To date, no dietary supplements, including vitamins and minerals, have significantly lowered the risk of kidney cancer recurrence. However, kidney cancer survivors should avoid high-sodium and high-fat diets to reduce kidney load while maintaining a healthy weight and controlling high blood pressure.
Prevention Methods
To avoid kidney cancer, you should immediately reject tobacco products and reduce exposure to harmful chemicals. Studies show that smokers who quit have a significantly reduced risk of kidney cancer, and the risk continues to decline over time.
Frequently Asked Questions
As mentioned earlier, because the kidneys are located deep within the body, it is difficult to notice any changes, and even if tumours grow, patients may not be aware of them promptly. Currently, there are no proactive methods for patients to check for kidney cancer. However, you should pay attention if you notice symptoms associated with kidney cancer, such as blood in the urine, back pain, or pain in the side. The presence of blood in the urine is particularly concerning and could indicate kidney cancer, so early medical consultation is advisable.
Any continuously growing tumour will damage nearby healthy cells and tissues and may even affect other areas. Therefore, the progression of kidney cancer can impact kidney function, and the longer the diagnosis or treatment is delayed, the greater the damage. Post-surgery effects depend on the extent of the kidney removed. With advances in medicine, most kidney cancer patients no longer need to remove the entire kidney; instead, only the part affected by cancer cells can be removed, preserving more kidney function.
As with all types of cancer, there is a risk of recurrence, and the likelihood of kidney cancer returning after treatment depends on the treatment method used. If a patient undergoes a nephrectomy, especially a radical nephrectomy, there is usually little cause for concern about recurrence, as the cancer cells should have been directly removed. However, for patients who undergo cryoablation, radiofrequency ablation, or embolisation, there is no guarantee that all cancer cells have been eliminated, and the risk of recurrence is relatively higher. Patients should pay close attention to hygiene practices during recovery to minimise the risk of recurrence.
While surgery is the most direct and effective method for eliminating cancer cells, it is not suitable for everyone. As mentioned earlier, most patients diagnosed with kidney cancer are over 65, and the risks associated with surgery are much higher for older individuals. Additionally, some patients may not be in a suitable health condition for surgery. Alternative treatments can also be effective, and doctors will make professional judgments based on individual circumstances, so patients who are unsuitable for surgery do not need to worry.
Kidney tumours can be benign. Doctors will first conduct thorough examinations to understand the tumour’s nature, location, and size. If the tumour is benign, there is no need for concern or to undergo the treatments above to remove it. However, approximately 95% of kidney tumours are malignant, meaning they are kidney cancer. Therefore, if you notice symptoms related to kidney tumours, do not take a chance by assuming the tumour is benign and avoiding medical consultation; if malignant tumours continue to spread, the damage to bodily functions can become increasingly severe.
▣ The information on this website has been reviewed by the HEAL Medical Team and is regularly updated according to the most recent clinical evidence. All content is provided for general informational purposes only and should not replace professional medical advice. Please consult your doctor or another qualified healthcare professional for personalized medical guidance.
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