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Active surveillance is the least invasive option for managing a kidney tumor. We prefer not to use terms like "observation" or "watchful waiting," as these indicate a passive approach where we wait for something bad to happen. Active surveillance is, by definition, an involved process where we keep an eye on your tumor, watch its growth characteristics carefully and reassess the need for treatment on a regular basis.
Why active surveillance?
Kidney tumors are biologically heterogeneous – this means they come in all shapes, sizes and behaviors. Some are completely benign tumors, some are cancers that behave like benign tumors and some can be very aggressive. Most small kidney tumors (less than or equal to 4cm) are either benign or behave like benign tumors. The bigger a tumor gets, the more likely it is a dangerous cancer and conversely, the smaller a tumor is, the more likely it is benign or behaves in a benign fashion. While we are very good at kidney surgery, not all patients need to undergo surgery – especially if they have a benign or benign-behaving tumor.
Who is a good patient for active surveillance?
Several patient and tumor characteristics make active surveillance an attractive option:
What does active surveillance involve?
The initial evaluation includes a complete history and consideration of other health risks, a thorough staging evaluation (imaging of the chest, abdomen, and pelvis), blood work and urine tests to evaluate kidney function. After the initial evaluation, we recommend repeat imaging every six months for the first two years, and annually thereafter. However, active surveillance is often tailored to the patient and the protocol is customized for each patient.
We prefer the first image to be a CT scan or MRI with contrast (if the patient can receive contrast). After the first image, we recommend ultrasound follow-up as there is no radiation, costs are relatively cheap and ultrasound is easy to perform. Tumor size and growth rates are evaluated with each image to determine if the tumor is changing in size or quality. We expect tumors to change over time – the goal is to catch the dangerous ones before they grow too large or leave the kidney!
Can these tumors be biopsied?
Percutaneous renal mass biopsy is an option for patients considering both surgery and active surveillance. Biopsy can often provide information regarding the malignant or benign nature of the mass. However, we expect most small renal masses to be low-grade, benign-behaving cancers and renal biopsy is not very good at telling the "good" cancers from the "bad." Researchers at Johns Hopkins are working right now to improve the performance of renal biopsy. Therefore, we decide on an individual basis, with each patient, if biopsy will be helpful.
What are the "triggers" for intervention?
Most renal masses grow at a slow and unpredictable rate. The average growth rate is about 1 millimeter per year, however some tumors can grow faster and some tumors can shrink away! The biggest trigger for intervention is overall tumor size. The risk of spread from the kidney increases from <1% at 2cm, to 2-3% at 3cm and 5-10% for tumors 4cm or larger (see kidney cancer staging). Growth rate (centimeters per year) is also a consideration and tumors that grow >0.5cm/year may indicate aggressive growth. With each active surveillance image, the need for intervention is reconsidered.
Can the tumor spread while on active surveillance?
The answer to this is unfortunately, YES. However, for a well-selected patient the risk of this occurring on surveillance is very low (<2%). Each patient and tumor are unique and this risk should be discussed with your urologist.
In patients who elect for delayed intervention, are the results compromised?
A recent study by Johns Hopkins urologists showed that a period of active surveillance did not alter results. In this study, patients delayed treatment of their small kidney mass by over 1 year. All were eventually treated with minimally invasive surgery successfully.
Does Johns Hopkins have an active surveillance program?
Yes, in 2009 urologists and researchers Phillip M. Pierorazio, MD, and Mohamad E. Allaf, MD, started the DISSRM Registry. DISSRM stands for Delayed Intervention and Surveillance for Small Renal Masses. The program catalogues the outcomes for patients who choose either active surveillance or surgery after a diagnosis of a small renal mass. Over the first several years, over 500 patients have enrolled in the program. The early results of the program are promising – no patient undergoing active surveillance has a spreading cancer or has died of kidney cancer. About 10% of patients initially electing active surveillance went on to surgery.
The DISSRM Registry continues to enroll patients and is seeking to define objective criteria for active surveillance, evaluates quality-of-life while on active surveillance, and is evaluating blood and urine from patients to find kidney cancer biomarkers!
For more information regarding management of Kidney Cancer or the DISSRM Registry contact Dr. Mohamad Allaf, Dr. Phillip Pierorazio, or Tina Driscoll, the study coordinator at 410-955-0163.