An international study shows that melanoma patients can have conservative lymph node surgery — dramatically reducing their chances of a permanent and often painful surgical complication — without compromising their survival.
The study at 64 sites, including Fox Chase Cancer Center in Philadelphia, involved more than 1,900 patients with melanoma that had spread from the skin tumor into a few "sentinel" lymph nodes — the first destination for tumor cells that break away and move into the lymphatic system. Current standard practice is to remove sentinel nodes and, if they are found to contain cancer, then cut out and check all surrounding nodes.
The study, published in this week's New England Journal of Medicine, compared that approach with a less aggressive method. Even though the sentinel node was cancerous, surrounding nodes were left in place and monitored regularly with ultrasound to look for changes. Those nodes were removed only if cancer was detected.
After an average of three years, 86 percent of patients in both groups were alive — no difference in survival.
There was a big difference, however, in rates of lymphedema, a permanent swelling caused by disruption of the lymphatic system. That surgical side effect plagued 24 percent of patients with complete node removal, compared with 6 percent of the monitored group.
Previous studies that were not as large and definitive also found no survival advantage.
If the new study "is insufficient to extinguish the enthusiasm for immediate completion lymph node [removal], then it is unclear what more is required," Memorial Sloan Kettering Cancer Center surgical oncologist Daniel Coit wrote in an editorial accompanying the study. "These results should be construed as practice-changing."
Jeffrey M. Farma, a surgical oncologist at Fox Chase and a co-author of the new study, echoed that sentiment, but added a caveat.
"Your patient has to be willing to be on a rigorous monitoring schedule," he said, "and come in to get an ultrasound" every three to six months, a commitment that can be time-consuming and nerve-wracking.
Although complete lymph node removal did not improve survival, it did reduce the chance of cancer recurrence. Almost 8 percent of monitored patients developed cancer in their nodes, which were then removed. Only about 1 percent of patients whose nodes were removed developed cancer in remaining lymph tissue in the same area.
At three years, about 68 percent of complete-node surgery patients had no recurrences anywhere in their bodies, compared with 63 percent of monitored patients.
The results "provide the last piece in the puzzle" of how to treat cancer that has spread from a tumor to nearby lymph node clusters in the groin, armpit, or neck, said surgical oncologist Mark B. Faries, who led the melanoma study while at John Wayne Cancer Institute in Santa Monica, Calif.
About 20 years ago, when sentinel node biopsy was pioneered (a tracer material is injected into the lymph system to identify these doorkeeper nodes), researchers assumed that cancer in the sentinels meant it was probably in nearby nodes.
"But it became apparent that all the cancer was in the sentinel node. About 75 percent of the time, the other nodes are cancer-free," said Faries, who is now at an affiliate of Cedars-Sinai Medical Center in Los Angeles. "So three-quarters of the time, you've accomplished your mission of eliminating cancer by taking out the sentinel nodes."
Breast cancer patients, who may develop lymphedema in their arms, may also benefit from lymph-node-sparing surgery, another study has suggested.
Left untreated, melanoma in a sentinel node will eventually invade other nodes. But research has revealed how the lymphatic system, which is part of the immune system, helps cancer hijack the bodies' defenses.
"It's easy for cancer to get to the sentinel node because it's not in a turbulent area, and the tumor prepares the sentinel node by suppressing the immune response," Faries explained. "It's harder for those cells to move to other nodes or through the body."