Sentinel Node Dissection Safe in the Treatment of Early Vulvar Cancer
Removing and examining one or two sentinel nodes in the groin and upper leg is an effective way to detect whether cancer has spread in women with early-stage cancer of the vulva, and also results in fewer adverse side effects, compared with the standard approach of removing many lymph nodes. However, extensive experience performing sentinel node dissection is necessary to prevent very small metastases from being overlooked using this technique.
Journal of Clinical Oncology, February 20, 2008 (see the journal abstract)
(J Clin Oncol. 2008 Feb 20;26(6):884-9.)
Like many other cancers, vulvar cancer usually spreads first to nearby lymph nodes. In the case of the vulva, the nearest lymph nodes are in the groin and upper leg (called the inguinofemoral region). Surgical treatment for vulvar cancer traditionally includes removal of the main tumor and many lymph nodes in the inguinofemoral region, a procedure called inguinofemoral lymphadenectomy.
While inguinofemoral lymphadenectomy provides excellent long-term survival without recurrence of disease, it can have many short-term and long-term side effects, including problems with wound healing, lymphedema, and persistent infections.
For this reason, researchers performed a clinical study to examine whether sentinel lymph node dissection (SLND) can be used safely in women with early-stage vulvar cancer, as it can be in breast cancer. With SLND, surgeons examine only the first few nodes into which the primary tumor drains. If no sign of cancer is found in these sentinel nodes, doctors assume the tumor has not spread and do not remove any further nodes.
Between March 2000 and June 2006 an international team of researchers led by the University Medical Center Groningen in the Netherlands performed SNLD while surgically removing the primary tumor in 403 women with early-stage vulvar cancer. Each of the 15 participating hospitals had a medical team with significant experience in the technique.
Of the 403 study participants, 127 turned out to have metastatic cells in their sentinel nodes and went on to have a full inguinofemoral lymphadenectomy. Some women with metastases also received radiation therapy. The other 276 women showed no signs of cancer in their sentinel nodes and so received no further treatment.
The investigators were able to follow nearly all the women for an average of 35 months after surgery, checking for short- and long-term complications as well as cancer recurrence in the groin, a major concern because it is often fatal.
The study's principal investigator was Ate G.J. Van der Zee, M.D., Ph.D., from the Department of Obstetrics and Gynecology at the University Medical Center Groningen.
Women who underwent only SLND had significantly fewer short- and long-term complications than women who underwent the additional inguinofemoral lymphadenectomy. Women who received postoperative radiation therapy in addition to inguinofemoral lymphadenectomy were even more likely to have recurrent infections in the affected region.
Among the SLND-only women, 3 percent (8 of 126) suffered a cancer recurrence in the groin, a rate the authors said was comparable to that reported for early-stage vulvar cancer patients treated with lymphadenectomy of any kind. What's more, the three-year disease-specific survival rate was 97 percent for the SLND-only women, meaning that the vast majority of them did not die of vulvar cancer during this period.
The authors caution that extensive clinical experience with SLND--for both the surgeon and the team supporting the procedure--is essential for replicating these positive results. Even with each hospital practicing the technique at least 10 times before joining the trial, metastatic cells in four out of eight of the patients who had a relapse in the groin were missed due to errors made in the SLND procedure.
"Implementation of the sentinel node procedure in routine treatment of early-stage vulvar cancer requires quality control at each step of this multidisciplinary procedure," state the authors. "To keep the experience at a high level, an exposure of at least five to 10 patients per year per surgeon should be regarded as a minimum figure."
"The low groin recurrence rate…and excellent disease-specific survival rate of 97 percent at three years in sentinel node-negative patients suggest that the sentinel node procedure is a safe alternative to inguinofemoral lymphadenectomy for selected vulvar cancer patients," concluded the authors.
"Sentinel lymph node evaluation seems to work well, but [only] in a center with a lot of expertise in that surgery," agrees Edward L. Trimble, M.D., M.P.H., of the National Cancer Institute's Cancer Therapy Evaluation Program.