For years, doctors have debated one another about what to do with little kidney masses, i.e., “small renal masses or SRMs” in doctor-talk. Patients hear this debate only when it applies to them, or if there is some hysterical headline about tumor cells escaping the tumor because a biopsy was taken. What is the reality, and what value does this have to the patient?
First of all, most large tumors/masses on the kidney are found by CT or other imaging. In the kidney tumor world, large can mean
For years, doctors have debated one another about what to do with little kidney masses, i.e., “small renal masses or SRMs” in doctor-talk. Patients hear this debate only when it applies to them, or if there is some hysterical headline about tumor cells escaping the tumor because a biopsy was taken. What is the reality, and what value does this have to the patient?
First of all, most large tumors/masses on the kidney are found by CT or other imaging. In the kidney tumor world, large can mean anything over 3 to 4 centimeters in size. Taking out my inch ruler with its handy centimeter imprint, I see that is just over an inch to about 1 1/2″ in size. Might be the size of a walnut to so–still doesn’t belong there, nor sound too insignificant to me!
Nevertheless, that is a Small Renal Mass, and is not even considered for treatment by some doctors. Our newer and more frequent imaging can find tumors of this size, long before they would be felt by a patient. They may or may not ever grow much larger, or do so very slowly. In fact, about 25% of these SRMs are not cancerous. Rather reassuring, except for the obvious conclusion that 75% of them are indeed cancerous! Size doesn’t matter in this case! Add to that the possibility of that benign mass may continue to grow and mutate/change over time. Its benign character may not remain benign.
Some 10% of these masses may subtypes of RCC which rarely grow,and imaging cannot determine that. The patient may be too old or ill for surgery at the time of discovery. A rush to surgery may not be appropriate but can a biopsy answer some questions–and is that dangerous?
Some have raised a concern that inserting a needle into the mass to get cells to examine is inherently dangerous, and could release cancer cells into the body, especially along the track of the needle. Of course, any mass large enough to be seen is likely already sending out cells in the course of its growth. The chances of any such cell becoming an established tumor is incredibly small, but every metastasis got started from some ambitious and lucky cell landing on a fertile spot in the body.
The reality is that there have been very few cases of obvious tumor seeding along the needle path, as a biopsy is taken. And these biopsies can be very helpful in determining whether or not the mass is cancerous. Thus a biopsy should not be avoided, if there is a question as to the nature of the biopsy or if surgery is considered inherently dangerous.
But does the biopsy give all the answers? Unfortunately, it does not, and especially since the typical biopsy will not differentiate between certain of the newly-discovered subtypes of clear cell renal cell. In short, some clear cell tumors may be destined to be more aggressive, while others may be very slow-growing. This can be analyzed only by a molecular review of the cells, which is not done typically. Thus, even a biopsy–now thought to be far safer than in earlier years–may not provide a solid guideline for the next treatment. Getting the molecular analysis, as described in a previous blog about ccA and ccB variants of clear cell RCC, will become essential for patients in the near future. Or so I fervently hope.