Kidney cancer is among the top 10 most common cancers in Singapore amongst males.

Kidney cancer, also known as renal cell carcinoma (RCC), accounts for 3% of all cancers in adults.

Certain lifestyles and environmental exposures can increase the risk of having kidney cancer such as cigarette smoking, obesity and high blood pressure (hypertension). Genetic syndromes and a family history of kidney cancer is a significant risk factor.

These genetic syndromes include von-Hippel Lindau (VHL) syndrome and tuberous sclerosis among others.

The classic triad of pain, blood in the urine (hematuria) and an abdominal mass only occurs in less than 10% of patients and most kidney cancers are detected incidentally in this day and age.

Surgical treatment has good results when the cancer is detected early while new medications are being developed to treat disease in advanced disease.

In this "Ask the Specialist" forum, Dr Kenneth Chen, Consultant from the Department of Urology at Singapore General Hospital (SGH), answers your questions on kidney cancer. SGH is a member of the SingHealth group.

This 'Ask the Specialist' forum has closed. Thank you for your interest and participation.

1. Question by eddiengsg
I went for a medical check-up. And my result shows that there is high sodium in my kidney. 148mmol/L. Is it a concern? What will happen if there is a high sodium in kidney? How to reduce it?

Answered by Dr Chen:
Thank you for your question. 

I believe it is a blood test showing the sodium levels in your blood rather than the kidney. At 148mmol/L, the levels are not critically high and should not be a concern. In severe cases of high sodium, patients can experience thirst or even lethargy. I would suggest a repeat check first as most times it may be due to benign causes such as dehydration. Do further consult your GP to see if a referral is warranted.

2. Question by Kitkat
I am a female 66 year old. Had microscopic blood in urine and had some tiny calcium crystalized particles in 2019. Had yearly 24-hrs urine test in 2020 and 2021 there were no more traces of blood. In 2022, I had spotting. Had kidney ultrasound and there was a few tiny cysts. Everything else were normal. No history of high blood, diabetes or anything. Two Pap smear tests were normal. Please advise if I need to be concerned.

Answered by Dr Chen:
Thank you for your question.

Microscopic blood in the urine is one of the most common referrals urologists get from the primary healthcare. Very often this is detected upon a health screening. The good news is that for the majority of people, this is benign and not something that is concerning. It can happen to both the young and the elderly. 

After further investigations, only about 5% of patients have an underlying cause detected such as urinary tract infection, kidney stones or even cancer. For the majority of people, the traces of blood in the urine is temporary and may disappear with repeat testing. 

Spotting is different from blood in the urine. Spotting refers to blood that originates from the vagina and points to a gynaecological cause. Post-menopausal bleeding should be investigated. Do further consult your gynaecologist with regards to this. 

If you have completed investigations both with the urologist and gynaecologist for both issues above and nothing significant is found then there is no cause for concern.

3. Question by ongpc
Doctor, it has been consistently all these years (more than 20 years) that I always have blood in my urine each time I take a urine test.    How can I tell it is time to take a deeper look - is it when the blood in my urine test exceed a certain mark?   Thank you for your advice.

Answered by Dr Chen:
Thank you for your question.

Yes, persistent traces of blood detected in the urine (microscopic hematuria) can be frustrating especially when the urine looks normal to the naked eye and tests have repeatedly come back negative.

There are many factors to microscopic hematuria and these range from simple issues with sample collection for example during menstruation (for females) or after vigorous exercise, when some degree of blood in the urine might be naturally expected, to more sinister causes such as bladder cancer or kidney cancer.

Nonetheless, when you are seen by a Urologist for investigation, a thorough check would have ruled out significant causes like infection, stones and cancer of the urinary tract. Through special urine tests, we can also tell if the red blood cells (RBCs) found in the urine are actually from microscopic bleeding along the urinary tract as seen in the case of infection, stones and cancer or the red blood cells have gotten there by "leaking" into the urine during the normal filtration process of the kidney. If these red blood cells are found to be due to "leaky" kidneys, this could signify a different set of problems with the internal health of the kidneys instead. A further consult with the renal physician or nephrologist will be arranged if that is the case.

There is no threshold for the amount of RBCs to determine if one needs more attention, however generally speaking, the higher the number of RBCs the more likely an underlying cause is present. If you have undergone a thorough detailed check by the Urologists and none of the above has been found, then there should not be any cause for concern.

Followup question by ongpc
Doctor, besides red blood cells in my urine, I also consistently have white blood cells in my urine too.   It is assymatic ie no symptoms.   Occasionally, I get burning sensation after urination, but the burning sensation would always go off after some time (like 10-15 minutes).   Do I need to worry?   Thank you for your advice.

Answered by Dr Chen:
Thank you for your question.
This is not an uncommon scenario from patients. White blood cells indicate some element of inflammation which can arise from the lower urinary tract especially if accompanied by burning sensation either in the lower abdomen or along the urethra (where urine exits the bladder). 

This burning sensation is also known as dysuria. Dysuria along with white blood cells found in the urine would point towards inflammation and infection. This should be further confirmed with a urine culture which can help isolate the bacteria responsible. It is important to have your urine culture taken before starting any antibiotics as once antibiotics is started, the bacteria counts will drop and the culture may be negative. Knowing the bacteria responsible is confirmatory of an infection and also helps guide appropriate use of an effective antibiotic.

Although urinary tract infection is the most common cause for the above scenario that you have described, there are other less common causes that can account for persistent white blood cells in the urine and these include gynaecological infections (for females), inflammation due to previous radiation treatment in the pelvic area, cancer of the urinary tract and even tuberculosis infection of the urinary tract which is rare. 

Do seek further consult with your Urologist.

4. Question by Jeff
Hi Dr Chen, I have the following questions:

1.What is the difference between kidney cancer and kidney failure?
2.What is the age group most commonly affected by kidney cancer? Does it affect males more than females?
3.At what stage is kidney cancer most commonly detected and how is it detected?
4.Can kidney cancer lead to kidney failure, hence requiring dialysis?
5.What can I do to lower my risk of getting kidney cancer?

Thank you for your advice.

Answered by Dr Chen:
Thank you for the questions.

1.Kidney cancer is a malignant condition. This manifests as a tumour that grows from the kidney tissue and is also known as renal cell carcinoma. As with all cancers, the cancer cells are abnormal and grow in an uncontrolled manner ultimately causing death. In early stage cancer, treatment can potentially cure the patient. 

Kidney failure on the other hand is not a malignant process. It refers to a situation where your kidneys are no longer able to handle the demands of the body which include maintaining the body’s fluid balance and excreting toxins in the urine. End stage kidney failure requires the patient to be on a form of dialysis.

2.Kidney cancer is a disease of the elderly and majority of cases are detected above 60 years of age. It affects more males than females.

3.Most kidney cancers are now detected in the early stages due to better standards of healthcare and increased rates of health screening in the general population. In the early stages, kidney cancers are small and unlikely to cause any symptoms therefore most are detected incidentally during imaging done during a routine health screening such as ultrasound of the abdomen or during scans done to investigate other unrelated problems such as a CT scan. 

4.Kidney cancer can lead to kidney failure if the patient does not have a healthy other kidney to begin with, and the kidney with cancer needs to be removed as part of the cancer treatment. However if you have a normal healthy other kidney, even if the kidney cancer grows significantly to involve the whole of one kidney, you will not end up with kidney failure as the body can be sustained with only one kidney. This is also the reason why we can donate one of our kidneys for kidney transplants, as the body can make do with one healthy kidney. The more important determinants of one’s risk of kidney failure are diabetes and hypertension.

5.There is no known way to prevent kidney cancer, but the following factors may reduce risk:
◾ Quit smoking. If you've never smoked, don't start. 
◾ Maintain a healthy lifestyle – have a nutritious diet, regular exercise and maintain a healthy weight/avoid obesity. 
◾ Control high blood pressure
Other risk factors not within our control include: 
◾ Treatment for kidney failure. People who receive long-term dialysis to treat chronic kidney failure have a greater risk of developing kidney cancer. 
◾ Certain inherited syndromes. People who are born with certain inherited syndromes may have an increased risk of kidney cancer, such as those who have von Hippel-Lindau disease, Birt-Hogg-Dube syndrome, tuberous sclerosis complex, hereditary papillary renal cell carcinoma or familial renal cancer. 
◾ Family history of kidney cancer. The risk of kidney cancer is higher if close family members have had the disease.

About Dr Kenneth Chen

Dr Kenneth Chen is a consultant Uro-oncologist with Singapore General Hospital (SGH). He has special interests in Robotic and Minimally Invasive Surgery and Genitourinary Oncology, having completed a fellowship at Sir Peter MacCallum Cancer Centre in Melbourne Australia.

His academic interests include prostate cancer diagnostics and novel device development where he is currently working on a drug eluting stent for the treatment of ureteric diseases.

He holds the teaching position of a clinical assistant professor with Duke-NUS Graduate Medical School and is a clinical lecturer with the National University of Singapore YLL School of Medicine.

Ref: J22