Kidney cancer patients may be overtreated, U-M study finds

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Studies have shown that for tumors smaller than 4 centimeters, removing only the tumor and a small margin of healthy tissue is just as effective at controlling the cancer as removing the entire kidney, an operation called total nephrectomy. At the same time, by sparing the remainder of the affected kidney, patients may be less vulnerable to long-term declines in kidney function - a concern particularly relevant for patients with other conditions that affect the kidneys, such as diabetes or high blood pressure. In addition, sparing a portion of the affected kidney creates more options if a new tumor develops in the patient's second kidney, a risk confronting a small number of people with kidney cancer.

The study looked at 14,647 people treated from 1988 to 2001 for kidney cancers less than 7 centimeters in size. Data was obtained from the Surveillance, Epidemiology and End Results (SEER) registry, which collects annual data about cancer incidence, treatment and mortality. Results of the study appear in the March issue of the Journal of Urology.

The researchers found that during this 13-year interval, only 9.6 percent of patients were treated with partial nephrectomy, while the remaining 90 percent had their entire kidney removed. The smaller the tumor, the more likely patients were to receive partial nephrectomy, although even among this group, partial nephrectomy was infrequently used: 40 percent of patients with tumors less than 2 centimeters received partial nephrectomy, and 20 percent of patients whose tumors were 2 to 4 centimeters did.

One possible explanation for the larger number of total kidney removals, the researchers suggest, is that total nephrectomy is more likely than partial nephrectomy to be performed with minimally invasive laparoscopic surgery. This means only a small incision is needed and recovery is generally easier than with open surgery. Partial nephrectomy can be done laparoscopically but is technically difficult and is not offered at all hospitals.

"For most surgeons, myself included, partial nephrectomy, whether open or laparoscopic, is likely to be a more difficult operation than removing the entire kidney. Many surgeons are able to take the whole kidney out laparoscopically but are less experienced performing partial nephrectomy laparoscopically. At least for the most recent years in this study, such technical considerations may have swayed how doctors presented treatment options to patients and how patients decided what surgery to have," says study author David Miller, M.D., clinical lecturer in urology at the U-M Medical School.

Partial nephrectomy carries some unique risks, including a higher risk of bleeding or urine leakage after surgery. In general, however, these complications can be treated and have no long-term effects.

Not everyone with kidney cancer is eligible for partial nephrectomy. While tumor size is a major indicator of eligibility, other factors that should generally be considered include the location of the tumor within the kidney, overall kidney function, the presence of other medical conditions, including diabetes, high blood pressure and kidney stones, and patient preference. These factors were not available to be analyzed in this study.

When it comes to patient preferences, Miller likens the situation to early stage breast cancer, where patients face a choice between mastectomy, which removes the entire breast, or lumpectomy, which spares the breast but requires radiation treatment.

"It is very much a preference-sensitive treatment decision. Our job as doctors is to help patients understand that the two surgeries are likely to be similar in terms of treating their cancer, but that each is associated with a unique set of concerns that may have different meaning or significance to individual patients. An important point is that hospitals should be able to offer the whole spectrum of surgery - from open total nephrectomy to laparoscopic partial nephrectomy - to patients with small kidney tumors. As long as patients know these options are available, then they would be able to make an informed choice," Miller says.

The study authors did note that partial nephrectomy has become more common over time, suggesting that acceptance of this procedure is becoming more widespread among doctors and patients faced with a kidney cancer diagnosis. The use of partial nephrectomy may have continued to increase since 2001, although more recent data is not yet available for analysis.

The researchers plan further study to understand why partial nephrectomy may be underused. Increasing use of laparoscopic total nephrectomy may play a role; other possible explanations are that patients are making an informed choice to have their full kidney removed or that many of the cases studied were not eligible for partial nephrectomy.

"Even though partial nephrectomy appears to have important benefits and may be feasible, it is not being done that commonly. It's our job to figure out why that's happening. Do patients not want it? Are they not eligible? We need to make sure all the surgical options are available to patients so they can make the decision that's best for them," says study author Brent Hollenbeck, M.D., assistant professor of urology at the U-M Medical School.

University of Michigan Health System