Kidney Cancer

What is a Renal Mass?


Urologists are often asked to assess and surgically treat patients with a “renal mass.”

The term “renal” refers to the kidney, and a “mass” is simply a growth.

Therefore, renal mass is an all-encompassing term that refers to any abnormal growth in the kidney. It does NOT necessarily imply cancer.


Renal masses can be cancerous (malignant) or non-cancerous (benign).  The most common cancer of the kidney is called “renal cell carcinoma.” In most instances, these need to be treated as they can spread to other organs (metastasize) and cause death.


Non-cancerous growths also known as “benign tumors” are growths that for the most part are not dangerous and can be left alone.  Two most common examples are oncocytoma and AML (angiomyolipoma).  These often do not require treatment, with the exception of AMLs which can rupture and bleed if they are large (>4cm).


There are approximately 60,000 new cases of kidney cancer in North America every year. The incidence is rising, partly because most kidney cancers are now detected incidentally on imaging performed to investigate another issue (see below). Approximately 40% of kidney tumors are detected in this fashion.


The overall survival for all stages of kidney cancer combined is about 75%, but most patients who present with early localized tumor have better survival.


Average age at diagnosis is 65 years but kidney cancers can present at any age. Often patients with familial/hereditary kidney cancers present in their 30s or 40s. 


Risk factors for kidney cancer include:

-       Smoking

-       Obesity (interestingly obese patients often have low grade/early stage tumors)

-       High blood pressure

-       Male gender (more common in men than women)

-       African American ancestry

-       Certain hereditary/familial syndromes


How are kidney cancers staged?


Stage 1 – a tumor that is <7cm and confined to the kidney.


Stage 2 – a tumor that is >7cm and still confined to the kidney


Stage 3 – the tumor has spread into local lymph nodes, adrenal gland (hormone producing gland located just above the kidney), the fat surrounding the kidney, or blood vessels of the kidney


Stage 4 – the tumor has spread to other organs or beyond the kidney and it’s surrounding fat


How are kidney cancers diagnosed?


The majority of patients with kidney cancer or other renal masses (kidney growths) have no symptoms and feel perfectly well. The growth is detected on imaging performed for another reason.  For example a person may have a CT scan or ultrasound to investigate a problem with the liver or intestines, and unexpectedly a kidney growth is identified.


60-70% of patients with renal masses are identified in this fashion. These patients usually have early (stage 1 or 2) kidney cancer or a benign growth.


Only 5-10% of patients present with classic symptoms of kidney cancer. These patients usually have advanced (stage 3 or 4) kidney cancer.


The signs and symptoms of kidney cancer include:

-       Abdominal pain

-       Blood in the urine (hematuria)

-       Abdominal mass that can be felt by physician or patient

-       Blood work abnormalities (caused by hormones/chemicals produced by the tumor)


Is biopsy necessary to diagnose kidney cancer?


Unlike most other cancers, where a biopsy (sampling of the abnormal growth) is required to make a diagnosis before treatment, kidney cancers have a very typical appearance on ultrasound, CT scan, or MRI and generally this is enough to make the diagnosis. Therefore treatment is often administered without a biopsy and after the tumor has been removed from the body, the pathologist will analyze the tumor and comment on the grade (grade is a measure of aggressiveness) and the subtype of the tumor (some subtypes are more aggressive than others).


The risk of cancer recurrence after treatment depends on the grade, subtype, and stage of the tumor. Your urologist will devise a follow-up regimen (examination, blood work, imaging) based on these parameters.


However, in certain instances your urologist MAY recommend a biopsy before treatment. This is often done in patients with a very small mass (this will be further discussed in the following sections) or patients who have single kidney, reduced/compromised kidney function, suspected non-cancerous tumor based imaging, or very elderly patients with other significant medical conditions.


Kidney biopsy is a fairly straightforward outpatient procedure performed commonly by a radiologist. Using local anesthesia, a needle is passed through the skin into the kidney/tumor and a sample is obtained.


Biopsy DOES NOT cause the cancer to spread or seed into the surrounding tissues. 


Although generally very safe, complications can rarely occur. These include:

1)    Hematoma (bruising around the kidney) – 5% (generally self limited, no specific treatment needed

2)    Clinically significant pain (1.2%)

3)    Blood in the urine (1%)

4)    Pneumothorax (Air leak from the lungs – if the needle punctures the lung) (0.6%)

5)    Significant bleeding requiring blood transfuciton (0.4%)


What are the limitations of a biopsy?

1)    16% non diagnostic rate

2)    A benign biopsy does not always correlate with a truly benign tumor

3)    The biopsy is imperfect at predicting the grade of the tumor


Given these limitations, in young and fairly healthy patients, kidney cancer is treated surgically to avoid the uncertainties associated with biopsy.


How is kidney cancer treated?


Treatment of kidney tumors depends on whether the tumor is large or a “small renal mass” (see section on “small renal mass”).


Large tumors generally require complete surgical removal of the kidney along with the tumor and surrounding tissue (radical nephrectomy). Systemic therapy (pills designed to kill kidney cancer, immunotherapy) is also administered in conjunction in patients with stage 4 disease (metastatic cancer). This often involves a medical oncologist physician.


There are several other strategies that can be employed for small renal masses and these will be discussed in the respective section.


Radiation is generally not used in the treatment of kidney cancer.




What is a small renal mass/renal tumor?


Small renal masses are defined as kidney growths less than 4cm in size. These are a special subset of stage 1 tumors (tumors <7cm). Up to 20% of these tumors can be benign (non-cancerous). Your surgeon will discuss the best possible option for you.


In general treatment strategies for small renal masses include

1)    Surveillance

2)    Partial nephrectomy

3)    Radical nephrectomy

4)    Ablative techniques


Surveillance for small renal masses


In patients who are elderly or have other medical conditions, which can pose a greater threat to their well-being and longevity than a small renal tumor (for example significant heart disease or advanced chronic kidney disease), could be considered for surveillance. The rationale is to avoid unnecessary treatment and the potential complications of treatment in patients who are more likely to be affected by their chronic medical conditions than their kidney cancer.


Current data suggests that the probability of development of metastatic disease of a small renal mass (cancer spreading to other organs despite the small tumor size) is less than 2% while on surveillance.


There are 2 surveillance strategies:

1)    Expectant management – For patients with poor healthy/other major medical issues. Patient is surveyed (examination, imaging, blood work) every 6-12 months and treatment is administered only if the tumor spreads or symptoms develop. 


2)    Active surveillance – the goal here is to delay treatment (in patients that are otherwise healthy enough and eligible for treatment) of very small masses. The rationale is that some of these small tumors may progress very slowly or not at all, thereby avoiding treatment in a subset of patients. Your urologist will image you periodically (initially every 3-6 months and later on less frequent depending on the rate of growth/complexity of the tumor/history of growth). This strategy is often used for very small tumors <2cm.


Your urologist will use imaging characteristics and sometimes a biopsy to see whether your  tumor is safe enough to be observed for some time.


If the tumor shows a propensity to grow rapidly (>5mm per year), starts to show aggressive features on imaging, or grows to larger than >2-3 cm treatment can be discussed. 


In very young and healthy patients, this strategy is only employed in extremely well selected patients because the inherent risk of metastatic spread, albeit quite small.


Radical Nephrectomy


This is strategy is often avoided in patients in small renal masses. Since these tumors are small, it is often possible to remove the tumor only and preserve the remaining healthy parts of the kidney not involved by tumor (see the “partial nephrectomy” section for discussion and rationale for this). However, in certain instances, the location of the tumor is such as it is not technically feasible to remove the tumor and reconstruct the remaining kidney. In such instances, despite the small size of the tumor, a radical nephrectomy (complete kidney removal) is performed.


Ablative techniques


Under construction



Renal cysts


Under construction


On The Web

Canadian Urological Association


Kidney Cancer Canada


Canadian Cancer Society


National Cancer Institute


National Comprehensive Cancer Network


National Kidney and Urologic Diseases Information Clearinghouse

General Information on Cancer

UNDERSTANDING CANCER - Metrovan Urology info on the principles of diagnosis, staging, prognosis and more.

American Cancer Society

BC Cancer Agency: Good general website from the British Columbia Cancer Agency. Has contact information on locations.

National Cancer Institute: Excellent source of understandable and mainly unbiased information. Several very good brochures on every stage of prostate cancer.

National Comprehensive Cancer Network: peer-reviewed expert content/prostate cancer guidance on evidence-based cancer diagnosis and management. Best for Prostate and Kidney Cancer. The most in-depth information is located in the physician section and requires registration.

General Urology Websites

Canadian Urological Association  Extenstive library of downloadable pamphlets on a wide range of urological conditions

Cleveland Clinic

Mayo Clinic

Medline Plus Produced by the US National Institutes of Health with information on virtually every health topic and extensive list of links The patient information site of the American Urological Association.