The kidneys are organs about 12 cm (4 inches) long in the abdominal cavity, or about the size of your fist. VHL in the kidney may cause cysts or tumors. It is common for any adult in the general population to have an occasional kidney cyst. VHL cysts are usually multiple, but the presence of one or more simple cysts is not a problem in itself. It is also possible for tumors to form in the kidney that are renal cell carcinomas (RCC), one kind of kidney cancer, formerly known as hypernephroma.
There are generally no specific physical signs to help find problems early. It is critically important to begin monitoring the kidneys long before any obvious physical symptoms or signs occur. The kidneys continue to function while these structural changes are occurring, without physical symptoms, and with normal urine tests.
Think of it as having a mole on your skin, except that you cannot see that it is growing. When it is very small there may be no cause for alarm. When the mole begins to grow or change in suspicious ways your doctor would recommend that it be removed.
Similarly, when a kidney tumor is quite large when discovered, or if it changes shape, or its size or rate of growth becomes suspicious, your medical team may recommend surgery. Not all kidney tumors require immediate surgery. Based on characteristics such as density, size, shape, and location, they will recommend either a time to repeat the imaging tests or surgical resection (removal of the tumor). Once they emerge, VHL kidney tumors are like Clear Cell Renal Cell Carcinoma (ccRCC) in the general population.The biggest difference is that in VHL we have the opportunity to find them earlier than most people who have sporadic kidney cancer. That gives us much better options for dealing with them early, keeping that kidney working for you, and avoiding the worst consequences of cancer. Knowing that someone with VHL is at risk for RCC, the tumors can be found at much earlier stages. If you wait for symptoms, the tumor will usually be at a much later and more dangerous stage when it is found.
Opinions differ on the right time to operate, but there is widespread agreement on this general approach. In VHL, a person with kidney involvement typically has a series of tumors on both kidneys over the course of several decades. Clearly one cannot remove every little tumor, since that would be too many surgeries for the person, and especially for this small organ, to endure. The goal is to maintain the patient’s own kidney function throughout his or her lifetime, to minimize the number of surgeries and yet remove tumors before they metastasize and cause the cancer to grow in other organs. The tricky part is to choose the right moment to operate—not too early and not too late.
The objective is to track the progression of the cells from harmless to a later point, but before they become capable of spreading. If you think of a dandelion, it begins as a bud, becomes a rather pretty yellow flower, turns white, and one day the white seedlings are carried off on the wind to seed the lawn. If you pick the yellow flowers, the seeds are not mature and cannot spread. The cells have to mature to the point where they know how to seed themselves in the lawn. The trick to living with dandelions is to pick them while they are yellow.
There is a similar transition in cancer. Cancer researchers have identified a series of distinct stages that the cells go through before they are even capable of metastasizing.
It would be ideal if there were some easy blood or urine test—some biomarker—to check on the cell progression. There is no such test at this time, though there is a great deal of research effort to find one. Meanwhile, clinical research has shown that the size of a solid tumor is one relatively crude but fairly reliable sign of its progress.
Biopsies are usually not called for in this case, since with a diagnosis of VHL one is pretty certain what the structure will contain. There will be cancer cells even in very small tumors. The question is: what is their level of progression? This is not a question that can be answered accurately through a biopsy.
Cysts are generally not considered sufficient cause for an operation. There will be a small seedling of a tumor in the wall of the cyst, and it will be important to watch the size of that tumor, not of the cyst itself.
The consensus from the Freiburg (Germany) meeting (1994) was to recommend surgery only when the largest tumor is larger than 3 cm. This recommendation was verified by a multi-center study under Dr. Andrew Novick. (Steinbach, 1995.) All the VHL study teams worldwide now concur with this guideline. After nearly 20 years of experience using these guidelines, there are only three verified reports of metastasis from tumors smaller than 4 cm, all of which were at or greater than 3 cm.
In watching your kidneys, your medical team is working to evaluate whether you have cysts or solid tumors. You will need tests such as magnetic resonance imaging (MRI) or computed tomography (CT). The doctors will watch the tissue density, the position of the tumors, their size and rate of growth. MRI is preferred in most cases, as it does not use radiation.
It is important that you understand in as much detail as you can the medical findings that your medical team is concerned about, so that you can participate with them in determining the right timing and treatment. Don’t be shy to get a second opinion. The distinction between a cyst and a tumor can be debatable depending on the clarity of the image and the experience of the radiologist who reviews the VHL tumors. Even among experts there can be differences of opinion. This is an area where the perspective of one or more physicians with significant experience in VHL can make a world of difference. Films or compact discs (CDs) can easily be sent to a consulting physician far away, even in another country. Contact the VHL Alliance for assistance in locating an expert who can assist you.
Decisions about when to operate and the extent of the procedure need to be made by the entire team, especially including the patient, with full disclosure of all information. All points of view, the location of the tumor, the patient’s level of stamina and health, and even the possible desire of the patient to be free of the tumor, all play a role.
In cases where the last remaining kidney must be removed, VHL patients have been proven to be good candidates for kidney transplant. (See Goldfarb, 1997.) VHL tumors grow from abnormalities within the cells of the kidney itself. Since the new kidney has the donor’s genetic structure and two healthy copies of the VHL gene, it is not at risk for VHL tumors. Immune suppression for transplantation has not been seen to increase the growth of other VHL tumors.
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