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By John LeBas
Just a decade ago, localized renal tumors were almost always treated with radical nephrectomy. Today, surgery for localized renal masses can be much less extensive or even avoided altogether, yielding a higher quality of life for patients with cancerous and benign tumors confined to the kidney. Renal cancers are most effectively treated before they metastasize, and benign kidney tumors may also require removal because of their potential to affect function. Multiple kidney-sparing options, from maximally invasive to non-invasive, are available to patients with localized renal masses. Because of increasing incidence partly owing to early incidental detection, the majority of kidney cancers are now found in the early stages. “Ten years ago, we would have performed radical nephrectomy for almost all patients with localized renal masses. However, there are now very convincing data showing that removal of part of the kidney is just as effective as radical nephrectomy for such tumors,” said Surena F. Matin, M.D., an associate professor in the Department of Urology at M. D. Anderson. “Therefore, open partial nephrectomy has become our gold standard for curative treatment. And for older patients with very small and slow-growing tumors, we may be able to simply monitor the tumor without performing surgery at all.” Partial nephrectomy Also known as kidney-sparing surgery, partial nephrectomy is less disruptive to the patient’s system than radical nephrectomy. After radical nephrectomy, the patient is left with only one kidney (which may not function well, depending on other health issues) or no kidneys. When 50% or more of a person’s kidney function is removed, other conditions such as heart disease can accelerate. Partial nephrectomy was first used to treat patients with tumors smaller than 4 cm who would have been left without a well-functioning kidney if treated with radical nephrectomy. “However, it’s becoming increasingly clear that 4 cm doesn’t really mean anything. In fact, the size of the mass matters little to the outcome of the operation when it is performed correctly,” said Christopher Wood, M.D., an associate professor in the Department of Urology. Recent data suggest that partial nephrectomy can be successful for tumors up to 7 cm, and M. D. Anderson surgeons will consider partial nephrectomy whenever possible, regardless of tumor size. What matters more than size is the location of the tumor. Tumors that are at the center of the kidney are more difficult to treat with partial nephrectomy, but with a good operative strategy even these can be effectively removed while preserving the kidney. Tumors invading the renal sinus or vasculature present a higher risk of positive surgical margin and are better treated with radical nephrectomy. Tumors in the upper or lower pole of the kidney and those that are primarily exophytic—the majority of renal tumors—can usually be treated with partial nephrectomy. However, all else being equal, partial nephrectomy is more difficult than radical nephrectomy. During partial nephrectomy, the unresected portion of the kidney must be reconstructed to retain function and prevent postoperative bleeding and urine leakage. Reconstruction involves three main steps. First, vessels that have been transected must be suture ligated. Second, any defects in the urinary collecting system must be closed. Third, a compressive bolster must be sutured into the kidney to ensure complete hemostasis. Each of these steps requires fast and precise work. “Every time the heart pumps, 25% of the blood flows through the kidney,” Dr. Wood explained. “To perform renal surgery, we therefore have to clamp the renal artery, which temporarily stops the blood flow and allows relatively bloodless surgery. But we only have 30 minutes before the kidney begins to show signs of irreversible ischemic damage.” This time limit can make radical nephrectomy more attractive to the surgeon. Thus, despite the prevalence of tumors that can be treated with partial nephrectomy and the benefits of partial nephrectomy compared to radical nephrectomy, partial nephrectomy is still very much underutilized worldwide, Dr. Wood said. Other surgical options While most of the partial nephrectomies performed at M. D. Anderson are open surgeries, about 200 patients have instead undergone partial nephrectomy via traditional laparoscopy. Those patients generally have had very good outcomes with much less pain, shorter hospital stays, faster recovery, and better cosmetic results than patients who undergo open partial nephrectomy, Dr. Matin said. “International data suggest that laparoscopic partial nephrectomy carries an increased risk of bleeding and urine leakage after the surgery. But we have not seen this increased risk, likely because we carefully select patients who have favorable anatomic features.” The major downside to partial nephrectomy via traditional laparoscopy is that it is more difficult to complete the resection and reconstruction in the time allotted.
Newer robotic-assisted laparoscopic techniques for partial nephrectomy are now being tested. But with fewer than 100 patients worldwide having undergone robotic laparoscopic partial nephrectomy, it is too soon to say whether any benefit will be realized. “Robotic laparoscopy may help improve outcomes and it may help more urologists perform laparoscopic partial nephrectomies, which are very complicated when done with traditional laparoscopy,” Dr. Matin said. “But we have only short follow-up for the patients who have undergone robotic laparoscopic partial nephrectomy, and the early data don’t suggest a benefit. I suspect this is because it is early in the learning curve, but this learning curve is much less than with traditional laparoscopy, so it may be just a matter of time before we see a benefit.” Less-invasive ablative therapies, in which the tumor is heated (radiofrequency ablation) or frozen (cryoablation), may be offered to some patients with small kidney tumors. These therapies can be delivered percutaneously or laparoscopically, depending on the location of the mass. Radiofrequency ablation and cryoablation for renal tumors appear to be less effective than surgery, but they also carry a lower risk of complications. Thus, these less-invasive therapies may be appropriate for older, sicker patients, according to M. D. Anderson specialists. For all of the above-described procedures, M. D. Anderson urologists work closely with imaging specialists to develop the treatment plan. “With imaging, we can noninvasively assess key characteristics and extent of a growth in regard to the kidney’s most critical structures and therefore infer its potential evolution and impact on biological and physiological functions,” said Luc Bidaut, Ph.D., associate professor in the Department of Imaging Physics and director of the Image Processing and Visualization Laboratory. “With high-quality datasets, we can visualize the surrounding anatomy as well as a lesion’s vascularity and feeding vessels. All this information is key for the surgeons to decide which approach is best and then for planning the chosen intervention.” Said Dr. Matin, “It’s no longer about doing an ‘exploration’ and seeing what we can do on the fly, like in the old days. It’s about having a good road map, planning a strategy based on accurate imaging, and then executing that strategy.” Active surveillance Imaging is also very important to the least invasive of treatment options—active surveillance. Usually offered to patients who are older, as many at M. D. Anderson are, active surveillance relies on computed tomography in combination with other imaging modalities to determine whether a tumor evolves and may require surgery at all. To qualify for active surveillance, patients generally must have a kidney tumor that is smaller than 3 cm and asymptomatic. Such tumors carry an extremely low risk of local or metastatic progression, Dr. Matin said. Following the initial imaging assessment of tumor location and grade, follow-up imaging is used to monitor tumor growth. Usually, therapeutic interventions are triggered only if the tumor shows rapid growth or reaches 3 cm. “We’ve learned that patients with small or slow-growing tumors can be safely observed for disease progression and potentially avoid surgery,” Dr. Matin said. “We can really individualize the therapy and perform surgery only when it is necessary, which is also good because many of these patients are undergoing therapy for other cancers as well.” What is difficult, said Dr. Matin, is that imaging does not predict which tumors will grow and which won’t. But the ones that behave aggressively are more unusual. So far, only 10% of kidney tumor patients in the active surveillance program at M. D. Anderson have had to undergo surgery, and only half of those had a malignant tumor. Another 10% of the study participants have died of conditions unrelated to their renal mass. These statistics support the theory that most people with small and slow-growing kidney tumors do not need immediate treatment, Dr. Matin said.For more information, visit the Genitourinary Cancer Center at www.mdanderson.org. Other articles in OncoLog, September 2009 issue: Home/Current Issue | Previous Issues | Articles by Topic | Patient Education ©2010 The University of Texas M. D. Anderson Cancer Center |
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