by Dr Clarence Lei and Datuk Tan Hui Meng
There is no definite cause of kidney cancer. It accounts for 3% of all adult cancers, usually in the 5th to 7th decade of life. It occurs twice as common in men than women.
According to the National Cancer Registry for Peninsula Malaysia 2003, the kidney cancer incidence per 100,000 population in Malaysia is 1.7. This incidence rate increases to 15.6 per 100,000 population for males in the age group 60 to 69 years.
Some kidney cancers run in families and an increasing number of cases have been shown to occur this way. Patients known to have polycystic disease of the kidneys and advanced kidney failure are also more prone to develop kidney cancer.
What Are The Symptoms of Kidney Cancer?
Renal tumours are increasingly diagnosed with more widespread use of imaging techniques, e.g. ultrasound or scans. Patients with significant kidney cancers would present with blood in the urine.
In less than half the cases, the patient may actually notice a fullness or lump in the loin or the abdomen. One-third of patients may have non-specific syndromes, e.g. tiredness, fever or loss of weight.
About 20% of patients would already have the cancer spread to other organs and the symptoms may be referred to these organs, e.g. the lung, brain or bone.
In a series of 169 consecutive cases of kidney cancer operated on in a local medical centre :
* 65% were male and 35% female
* the age range was from 22 to 90 years, with a mean age 58.8 years
* 22% presented with back pain, 43.3% with blood stained urine and 12% had loss of appetite and weight
* 63% had duration of symptoms below 6 months, 23% had absolutely no complaint and the tumour was detected by routine ultrasound scan of the abdomen.
What Investigations Are Needed to Diagnose Kidney Cancer?
Unfortunately, there is no simple tumour marker (from a blood test) to screen for kidney cancer. Urine examination may show blood in the urine (haematuria), but there are many causes of haematuria, including cancers, urinary stones, infection or just inflammation.
The screening test of choice is usually an ultrasound scan. Ultrasound scans will be able to exclude non-cancerous lesions e.g. kidney cysts which are filled with fluid, or lipoma or fat containing benign tumours. Such fatty tumours often contain some muscle as well as vascular components and these tumours are known as angiomyolipoma.
Otherwise, more than 90% of solid masses of the kidney are cancerous. Therefore, renal masses are usually not subjected to the risk of a percutaneous biopsy.
At the time of the scan (usually ultrasound followed by CT or computerised tomogram), particular attention is needed to detect whether there is any local spread of the cancer to the nearby renal vein, which drains into the large main vein of the body known as the inferior vena cava (IVC).
Any enlargement of the nearby lymph nodes may indicate spread of the cancer.
What is The Treatment of Renal Cancer?
Surgery is the mainstay treatment. However, surgical cure is only possible if the tumour is in the early stages when the tumour is still confined to the kidney, i.e. Stage T1 or T2 (T2 when the tumour is more than 7cm).
Locally advanced stages include Stage T3 when the tumour extends to the tissues (including veins) near the kidney and T4 is when the tumour extends beyond the kidney fascia.
In about 25% of cases, the cancer would have spread beyond the kidney into the lymph nodes (N+) or to the distal organs e.g. the lung, brain or bone (M+).
Therefore, if there is any symptom attributable to these organs, further imaging in the form of CT scan of the lung, brain or bone scan is warranted.
What Types of Surgery Are Available For The Treatment of Kidney Cancer?
The standard surgical treatment is open surgery to remove the kidney cancer with the entire kidney. However, if the patient’s other kidney has poor function, this may result in the patient dependent on dialysis.
In such cases, efforts can be made to preserve some renal tissues in the kidney with the cancer and the procedure is known as a partial nephrectomy as compared to a radical nephrectomy (nephrectomy = surgical removal of kidney).
Partial nephrectomy is also indicated in patients who have tumours in both kidneys as removing both kidneys would mean the patient would be dependent on dialysis.
However, if it is technically not possible to do partial nephrectomy, a total nephrectomy would be indicated to remove the cancer as it is usually more important to be cancer-free and rely on dialysis, rather than to die from residual kidney cancer!
What About Small Renal Tumours That Are Found on Routine Scanning?
With widespread use of ultrasound and CT scan, many asymptomatic small renal tumours have been diagnosed. According to clinical studies (e.g. a recent study on 287 small renal tumours published in the September 2006 issue of the Journal of Urology), solid renal tumours more than 3 cm are likely to be cancerous. Therefore, renal tumours more than 3cm should be removed surgically.
What About Various Types of 'Keyhole' Surgery for Renal Tumours?
In addition to open surgery for renal tumours, some centres have the facilities for laparoscopic surgery. In addition, in centres with a surgical robot (the 'Da Vinci' system), robot assisted laparoscopic surgery can be performed.
Other energy sources may be used to ablate the renal tumours, e.g. radio frequency (RF), high intensity focussed ultrasound (HIFU) and freezing (cryosurgery).
The energy source can be delivered percutaneously or by laparoscopic means and under ultrasound guidance. However, these techniques cannot reliably ablate all the tumour cells and are only indicated in special situations e.g. multiple superficial tumours in patients who are not fit surgery.
What Is The Treatment For Kidney Cancer That Has Spread To The Other Organs?
There is still a role for open surgery if the lesion in the lung or brain is solitary and is stable. Such lesions can be removed by surgery.
In patients whose cancer has spread outside the kidney, those lesions can be treated by systemic therapy. Before systemic therapy, the large primary tumour in the kidney should be removed to improve the effectiveness of the systemic therapy.
There are 2 forms of systemic therapy for such metastatic renal cancer, namely, immunotherapy with agents such as interferon to boost the patient's immune system against the cancer cells.
In 2007, new agents (e.g. sunitinib and sorafenib) have been used with some effect against metastatic renal cancer. These agents work by reducing the growth factor supplied to the tumour via the new vessels (i.e. anti-angiogenesis action). However, these new drugs are extremely expensive.
Radiation is not effective against renal cancer.
What Is The Long-term Outcome and Follow-up of Kidney Cancer?
For early stage renal cell carcinoma, the five-year survival rate is more than 80% after removal of the tumour and kidney. After the surgery, the patient is usually followed up to 3 to 6 monthly with imaging (chest x-ray, ultrasound or CT) for 3 years, and thereafter, yearly for life.
For patients who have metastatic disease, the follow-up is usually on a 1 to 2 months' basis to monitor the progress of the cancer in response to the systemic therapy.
Once the tumour has spread out of the kidney, the long-term prognosis is poor.
More info on KIDNEY CANCER here.