Thursday, July 1, 2010
The more lymph nodes that are surgically removed from the abdomen after receiving chemotherapy for testicular cancer, the less likely it is that the cancer will return, suggests a new study conducted by a team of Memorial Sloan Kettering Cancer Center investigators.
Over the past 15 years, many surgeons have attempted to limit the areas that are dissected in this routine post-chemotherapy surgery. Because one of the main side effects of the operation is the loss of the ability to ejaculate normally, doctors have hoped that they could preserve more of the nerves that serve ejaculation by touching less tissue during surgery. The study’s findings suggest that it may be time to put an end to such tinkering with these surgical templates.
“By limiting the area of dissection, you can preserve forward ejaculation,” says lead author Brett Carver, a urologist at Memorial Sloan Kettering. “But you may also be compromising the effectiveness of the surgery.” (Forward ejaculation is defined as ejaculate being projected from the penis.)
An Aggressive, Yet Treatable Cancer
Testicular cancer is a rare malignancy, with only about 8,000 cases diagnosed in the United States each year. When the disease does strike, however, it can be highly aggressive. About two-thirds of patients are first diagnosed with disease that has spread, or metastasized.
“Without treatment, the disease is 100 percent fatal,” says Dr. Carver. “But the good news is that only about 300 men a year die from it.” It turns out that tumors of the testes are highly responsive to chemotherapy and subsequent surgery, resulting in a long-term survival rate of about 90 percent.
The most common site to which testicular cancer spreads is behind the tissue that lines the abdominal cavity. This area, called the retroperitoneum, contains the aorta (the main artery coming from the heart’s left ventricle) and vena cava (the main vein leading to the heart), as well as a large number of lymph nodes. Since residual tumor cells and teratomas — cells that withstand chemotherapy and may later become cancerous — also commonly reside here, a surgical dissection is almost always performed after chemotherapy
About 30 percent of testicular cancer patients will have viable tumors or teratoma after chemotherapy, even if the lymph nodes appear normal, notes Dr. Carver. The larger the area a surgeon removes, the more lymph nodes, tumors, and teratomas are removed.
A pathologist’s postoperation node count could therefore be used as a measure of the extent of the surgery. But just how far should a surgeon go? Is there a limit to the benefits beyond a certain number of nodes?Back to top
Identifying the Best Surgical Strategy
In search of answers, Dr. Carver and his colleagues followed 432 testicular cancer patients who had undergone post-chemotherapy lymph node removal at Memorial Sloan Kettering between 1989 and 2006, and who were found to have either teratomas or scar tissue known as fibrosis. Previous research has shown that approximately 10 to 15 percent of such patients will suffer disease recurrence.
Cancer did return in 30 patients (7 percent), half of whom experienced the relapse within three years of surgery. The researchers found that for every ten nodes removed, the risk of recurrence dropped by about 25 percent. When ten nodes were removed, approximately 90 percent of patients stayed relapse free for at least two years. That figure rose to 95 and 97 percent, respectively, for 30 and 50 nodes, report the researchers in the June issue of the journal Urology [PubMed Abstract].
“We found that the more lymph nodes you remove, the better patients do,” says Dr. Carver. This is likely the result of both the removal of residual disease and a more thorough postsurgery pathologic evaluation. His team found no evidence of a ceiling on the benefit.
Further, potential side effects are now of less concern. Today, surgeons can identify the nerves involved in forward ejaculation during surgery to remove the cancer and are able to perform a procedure to spare them.Back to top
Surgical Standards into the Future
The findings support the current protocol at Memorial Sloan Kettering, which is to remove the left and right retroperitoneal lymph nodes surrounding the aorta and the vena cava, regardless of whether the testicular cancer was present in the left or right testicle. Nerves responsible for forward ejaculation are spared whenever feasible.
“That’s not the way it has always been. Modified templates were once used here,” notes Dr. Carver who, along with Joel Sheinfeld, the senior author on the study, performs these surgeries at the Center.
“We now know that limiting dissection potentially puts patients at risk,” he adds. “So, when we do the surgery, our goal is to remove all the lymph nodes in the entire anatomic region where testicular cancer could potentially metastasize.”Back to top