Wednesday, April 18, 2018
Across the United States, there is a disparity in the rate of people who are candidates for a partial nephrectomy — those with small renal tumors — and those who actually have the procedure.
Research shows that this is mainly because the operation is challenging and associated with more complications than a radical nephrectomy. (1) But also, many people with small renal tumors are unaware that a partial nephrectomy is an option as urologists often don’t discuss it with them. (2)
Around 15 years ago, the standard approach for all newly discovered kidney tumors, regardless of size, was the removal of the entire kidney. However, during the last 40 years, it has become increasingly clear in other fields of oncology, such as breast cancer and limb sarcoma, that organ-sparing operations, often combined with chemotherapy and radiation treatments, can provide equivalent oncological outcomes to the more radical procedures routinely done in the past.
Clinical research conducted at Memorial Sloan Kettering Cancer Center (MSK) and confirmed elsewhere in the United States and abroad, indicated the same was true for kidney tumors. This insight led to the era of kidney-sparing, or nephron-sparing, surgery.
MSK researchers and surgeons helped spearhead elective partial nephrectomy, a procedure that can potentially preserve renal function. Today at MSK and other major centers, it is used to treat almost all small renal tumors. (3)
Burden of Disease
In 2017, there were an estimated 64,000 new cases of kidney cancer (renal cortical tumors) and approximately 14,000 deaths from the disease. The medical understanding of this cancer has markedly expanded in the last decade, with the implementation of molecular biology and metabolomic research techniques. (4), (5) There are now at least 30 distinct families of renal cortical tumors that can be assigned to broad categories of anticipated clinical behavior, ranging from benign (20 percent, including renal oncocytoma and angiomyolipoma), to indolent (25 percent, including papillary and chromophobe carcinoma), to malignant (including the classic conventional clear cell carcinoma). It is imperative to note that the anticipated growth rate of kidney tumors is approximately 0.3 centimeters (cm) per year, meaning that tumors of all sizes are present for many years or even decades before clinical diagnosis.
Today, most kidney tumors are discovered incidentally at a small and highly curable size (<4 cm) via enhanced radiological imaging techniques, often performed for nonspecific abdominal and musculoskeletal complaints or during unrelated cancer care. However, approximately one-third of people with kidney cancer still present with massive palpable, symptomatic tumors that have destroyed most of the involved kidney; extended locally into surrounding tissues, including the renal vein or inferior vena cava; involved the regional lymph nodes; or metastasized to distant organs, most commonly the lungs. People with large tumors may also present with hematuria, anorexia, or weight loss.
At MSK, kidney surgeons, medical oncologists, and nephrologists collaborate to provide the best care for patients, utilizing basic and clinical research spearheaded by the faculty. The two distinct presentations of kidney tumors are treated with the surgical strategies summarized below.Back to top
Small Localized Kidney Tumors and Partial Nephrectomy
Initially, the partial nephrectomy approach was restricted to tumors 4 cm or less in size (T1a), (6) but it has been expanded to treat larger tumors (T1b) when technically feasible. (7) The major caveat of the approach is a small but real chance of new tumor formation, about 5 percent over the patient’s lifetime, which could require another surgery. However, a wealth of clinical information indicates that kidney-sparing surgery provides equivalent oncological outcomes to radical nephrectomy for small renal tumors while at the same time maximally preserving renal function and preventing or delaying the onset of chronic kidney disease and its associated potential for cardiovascular morbidity and mortality. (8)
This favorable impact on renal function preservation is particularly important in patients with pre-existing and common medical conditions that can adversely affect baseline kidney function, such as diabetes and hypertension. My colleagues and I have also provided evidence that chronic kidney disease is more common in people with kidney tumors and can be considered a risk factor for the disease. (9)
Today, partial nephrectomy is considered the option of choice for healthy people with a small renal mass, in large part due to MSK’s academic efforts and teaching. The approach is also supported by major surgical and oncological guideline committees, following exhaustive reviews of the literature. (10), (11)Kidney sparing can also include active surveillance strategies, when small renal masses are detected in elderly and comorbidly ill people for whom surgical interventions provide more significant risks than benefits.
Although partial nephrectomy remains a challenging operation, MSK surgeons offer an array of approaches, including open mini flank, laparoscopic, and robot assisted, and they perform approximately 400 operations a year. People having a partial nephrectomy can expect long-term survival in the range of 90 percent and possibly higher, depending on the histological subtype of the tumor. However, within the pool of small renal tumors, a small percentage of tumors have a molecular signature of potential future lethality; (12) therefore, long-term surveillance for both local tumor recurrence and metastatic disease evolution is essential.Back to top
Locally Advanced and Metastatic Renal Tumors: Radical Nephrectomy
Although our group avoids performing radical nephrectomy for small kidney tumors, people presenting with massive tumors that have destroyed most of the kidney, invaded the renal vein and its branches or the vena cava, or metastasized to regional lymph nodes or other organs do require radical nephrectomy. (13) This operation removes all the surrounding soft tissues, regional lymph nodes, and sometimes the adjacent adrenal gland. It provides local tumor control and usually alleviates symptoms of pain, hematuria, and systemic symptoms — such as anemia, hypercalcemia, fatigue, and anorexia — that arise from the tumor.
Depending on the final pathology reports and the extent of metastatic disease, radical nephrectomy patients are often referred to MSK’s medical oncologists for consideration for participation in clinical trials testing adjuvant or systemic agents designed specifically to attack kidney cancer, such as tyrosine kinase inhibitors and checkpoint inhibitors. (14) In some cancers, like breast and colon, adjuvant treatment is the standard of care. However, in kidney cancer, the search for the next best step after the surgical removal of massive renal tumors is an ongoing and very high institutional priority. (15)
Radical nephrectomy is also performed in people diagnosed with a massive kidney tumor and documented metastatic disease at the time of presentation. This operation, called a cytoreductive radical nephrectomy, removes the largest tumor burden and achieves local tumor control. It also provides the oncology team with information regarding the precise tumor family, informing the selection of the best drug from the full array of available systemic agents or helping to match patients to the latest clinical trials. (16)Often, cytoreductive radical nephrectomy dramatically improves symptoms. If the metastatic tumor is minimal, a period of observation lasting many months or even years may ensue before systemic treatment is initiated. (17)
In addition, recent work done at MSK and confirmed at other major centers indicates that up to half of all of people undergoing radical nephrectomy for large renal tumors recover their renal function to baseline in two to three years. (18)As with partial nephrectomy, MSK’s surgeons perform radical nephrectomy with the full array of open and minimally invasive approaches.Back to top
The amount of progress in understanding kidney tumors in the last 15 years is truly remarkable. At MSK, a multidisciplinary research team comprised of surgeons, oncologists, pathologists, molecular biologists, epidemiologists, radiologists, and nephrologists has made many clinical and scientific discoveries that shape the daily practices and provide increasing hope for people with what was once considered a lethal tumor. The aim for the future is precise and careful surgical removal of the primary tumor, molecular characterization of the tumor, and the identification of unique targets suitable for systemic therapies.Back to top