Lymphatic Mapping Studied in Cervical, Vulvar Ca.
"Lymphatic mapping is going to change the course of treatment in gynecologic cancer," said Dr. Levenback of the University of Texas M.D. Anderson Cancer Center, Houston.
"Compared to the gold standard, which is lymphadenectomy, it will mean less morbid procedures; better treatment selection; and, hopefully, better outcomes for patients," he said at the annual meeting of the Society of Gynecologic Oncologists.
Lymphatic mapping involves the injection of blue dye or a radionuclide, or both, adjacent to a cancerous tumor to identify the sentinel lymph nodes into which the tumor drains. Once identified, the sentinel nodes are removed for examination by a pathologist.
The goal of the procedure is to spare the patient from the more invasive full lymphadenectomy and the consequent risk of lymphedema. Adjuvant chemotherapy may be prescribed when a positive sentinel node is detected.
Although pioneered in the fields of skin and breast cancer, lymphatic mapping and sentinel lymph node biopsy have since been explored in Merkel cell cancer and cancers of the head and neck, stomach, colon, esophagus, anus, thyroid, penis, and vulva, Dr. Levenback said at the meeting.
He presented his experience with 39 patients diagnosed with invasive cervical cancer who were scheduled to undergo radical hysterectomy and pelvic lymphadenectomy.
Before the procedures, all patients underwent preoperative lymphoscintigraphy as well as intraoperative lymphatic mapping.
"It is too early to rely solely on sentinel node biopsy in these patients. We are still testing the technique to see how it compares to the standard lymphadenectomy," he said.
Preoperative lymphoscintigraphy identified at least one sentinel node in 87% of patients, while intraoperative lymphatic mapping identified sentinel nodes in all patients.
A total of 132 sentinel nodes were identified clinically using these techniques, compared with 185 sentinel nodes identified histologically after lymphadenectomy.
"The good news is that we were able to identify sentinel lymph nodes in our patients and that in most cases the cancer had not spread beyond these nodes," Dr. Levenback continued.
In 31 patients, the sentinel node and the nonsentinel nodes tested negative for metastatic disease.
In six patients, the cancer had metastasized to the sentinel node but not to other nodes. There was one patient in whom malignancy was found in the sentinel node as well as in a nonsentinel node.
And in one patient, although the sentinel node was negative, another nonsentinel node tested positive, he said.
"Lymphatic drainage in the pelvis is very complex, and sometimes we run into situations where it is not always clear which nodes are sentinel and which are not. This is an area that needs more investigation," Dr. Levenback explained.