Last week, we started our discussion of kidney cancer. Today we are going to focus on those small renal masses that I mentioned last week.
What is a small renal mass (SRM)?
SRMs are defined as masses in the kidney that are less than 4 centimeters (cm) in diameter. Here are some features of SRMs:
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They are often benign, either cysts or benign tumors.
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They are usually diagnosed incidentally (by chance) on an imaging study done for symptoms unrelated to the kidneys.
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Clinical symptoms related to the kidneys are very rare.
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Most malignant SRMs are low stage and low grade and have a good prognosis (projected course and outcome).
What is the recommended treatment for SRMs?
Current recommendations are to consider “Active Surveillance”. This doesn’t mean that none of them should be removed; just that we carefully consider whether they should be removed or not. Sometimes the risk of removing them may outweigh the risk that the tumor poses.
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Tumors smaller than 2 cm are ideal candidates for active surveillance due to the low likelihood of tumor spread during the period of observation.
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Tumors between 2 and 4 cm can be safely watched in certain circumstances, based on a number of factors.
What is active surveillance for SRMs and how does it work?
Active surveillance is simply observing a kidney mass through regular imaging over time. What happens during active surveillance depends on the circumstances of each individual patient.
It usually starts with a complete staging evaluation to rule out spreading cancer. It may include a biopsy, but a biopsy is not always needed.
Initially, imaging will be recommended every 3 to 6 months to determine how quickly the tumor is growing. If it is not growing, or growing very slowly, the imaging may be spaced out to every 6 or even 12 months.
What determines whether you are a candidate for active surveillance?
Active surveillance may be recommended if you:
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Have poor kidney function – Removing any part of a kidney could worsen your kidney function, maybe even leading to the need for dialysis.
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Have hereditary forms of kidney cancer (proven by genetic testing) that increase your risk for multiple tumors on both sides. These tumors are typically watched until they reach 3 cm.
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Have predominantly cystic tumors – These tumors are less likely to progress.
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Have medical problems that require blood thinners.
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Are older or have multiple medical problems that increase the risk of surgery.
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Are recovering from a serious medical issue – which increases the risk of surgery temporarily (such as a heart attack).
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Do not want to have surgery or other treatment.
What triggers the recommendation of treatment beyond active surveillance?
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Tumor growth of 5 millimeters (0.5 cm) or more in a year.
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Change in the tumor appearance on imaging to appear more solid.
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A change in your health that lowers your risk of surgery – Such as no longer needing blood thinners or recovering from a serious medical issue.
Can your tumor spread while on active surveillance?
Yes, it can spread, but the risk is extremely low. The risk of spread based on tumor size is:
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Tumors less than 2 cm have less than 1% risk of spread.
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Tumors 3 cm have 1-2% risk of spread.
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Tumors 4 cm have 3-5% risk of spread.
Active surveillance for kidney tumors 4 cm or less is a safe initial option for many patients. Delaying intervention does not limit treatment options or lead to worse outcomes. However, if you and your doctor chose this option, you MUST commit to lifelong follow-up imaging as recommended by your doctor.
Next week, we will talk more about kidney cancer diagnosis and treatment other than active surveillance.
If you have any questions about small renal masses or active surveillance, please log into your account and send us your question. We are here to help.
Dr. Anita Bennett MD – Health Tip Content Editor