Definition:
Active surveillance is also known as watchful waiting or observation and this is the least invasive treatment strategy for kidney cancer. The term “active surveillance” is preferred as it is most accurate regarding this process.

Active surveillance simply means that a physician and a patient are working together to actively observe an identified renal mass. Once a radiographic test has identified a kidney lesion that is potentially kidney cancer, radiographic tests such as a CT scan, MRI scan, or ultrasound are done at regular intervals to observe the mass.

Active surveillance is a reasonable option for some patients as small renal masses are generally reliable in their growth rate and pattern. Studies have demonstrated that small renal masses tend to grow at a rate of 0.1 to 0.8 cm per year. Some kidney masses that are small and grow slowly can be observed and treated in a delayed manner. Alternatively, kidney masses that grow more quickly are suspicious for kidney cancer and should be treated.

Typically, after identifying a renal mass that is suspicious for kidney cancer, follow-up radiographic imaging is scheduled 3 to 6 months later. If there is no change in the mass, you and your doctor can coordinate an individualized surveillance schedule with which you are both comfortable. Typically, this involves obtaining radiographic imaging every 6 to 12 months with consultation at each time point.

Active surveillance is by definition an active process. Coordinating the radiographic imaging with routine discussion with your doctor is critical to the success of active surveillance. If the kidney mass should grow or change in character, then intervention may be required.

Candidates:
There are a number of important patient and tumor parameters that are critical in deciding the type of treatment that is best for a small renal mass. Considerations are numerous but include: the size and general radiographic appearance of the mass, the local anatomy of the mass, the overall age and health condition of the patient, overall kidney function, the number of lesions in the kidney, patient personal preference, etc.

Regarding characteristics of the renal mass, the smaller the kidney mass, the better suited it is for observation. Smaller kidney masses are less likely to be aggressive cancer and are also less likely to spread (metastasize). Regarding patient characteristics, the best candidates for active surveillance are older patients who have medical problems. Older patients with medical problems are at slightly higher risk of complications from surgery, and may benefit from close radiographic monitoring of their kidney mass. If the kidney mass remains the same size or has a minimal change in size, then active surveillance is continued. Alternatively, if the mass should grow, intervention with a minimally invasive management strategy such as ablation, laparoscopic partial nephrectomy, or laparoscopic radical nephrectomy can always be performed.

Advantages and disadvantages of active surveillance:
The major advantage of active surveillance is that no procedure is required. All procedures, no matter how “minor” or minimally invasive, are associated with complications. Active surveillance is not a procedure, and therefore does not have the risks of any invasive procedure. Also, most kidney masses grow slowly at a reliable rate so that the risk of a cancer growing rapidly and spreading is quite small.

However, active surveillance is not for everyone. Some patients are not comfortable with the idea of possibly having, and just observing, a kidney cancer in their body. For some patients, the idea of having a potential cancer under observation is very anxiety producing. Additionally, while small renal masses are relatively predictable in their growth rate, there is a small risk of tumor spreading during the course of observation.

Copyright 2006 Kidney Cancer Institute