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ABSTRACT & COMMENTARY
Decesare and colleagues have reported a study in which they injected technetium-99-labeled sulfur colloid at the site of primary vulvar cancer and then used an intraoperative gamma counter to identify one or more sentinel lymph nodes. The purpose of their study was to identify sentinel lymph nodes using intraoperative lymphoscintigraphy. Ten patients underwent bilateral inguinal and femoral lymphadenectomy. The clinical stages were as follows: T1 in six patients, T2 in two patients, and T3 in two patients. A total of four groins (3 patients) were positive for metastases. In one patient, only the sentinel node was positive for tumor. In a second patient, two unilateral nodes were positive for tumor, and both were identified with the gamma counter as sentinel nodes. In the third patient, a single sentinel node was positive for tumor in each groin; multiple nonsentinel lymph nodes were postive in each groin in this patient.
In no case was the sentinel node negative when other nonsentinel nodes were positive. DeCesare et al conclude that intraoperative lymphoscintigraphy quantitatively identifies one or more sentinel lymph nodes. Since sentinel lymph nodes can be localized transcutaneously, this technique may be useful for selective lymphadenectomy.
Vulvar cancer is a rare malignancy that principally affects older women. Despite delays in diagnosis, it is usually detected in the early stages (I and II) and, consequently, has a high cure rate. Historically, however, treatment has been radical, and late morbidity has been great, with sexual dysfunction, genital prolapse, and incontinence related to the radicality of the vulvar surgery, and lymphedema and infection related to the extensive inguinal and pelvic lymphadenectomy procedures. Over the past two decades or so, some groups have pushed the envelope to study less radical surgery for selected patients. This story has somewhat paralleled that of breast cancer, with fewer procedures for the primary lesion and less extensive node dissections for regional spread. Since the late 1970s, our goup at M.D. Anderson Cancer Center has employed wide radical excision and selective lymphadenectomy for patients with T1 and T2 vulvar cancer instead of the traditional radical vulvectomy and bilateral inguinal lymphadenectomy. Other groups have pursued this strategy as well. The results have been quite gratifying, with equivalent cure rates combined with much shorter hospital stays and much less late morbidity. Unquestionably, the quality of life of the patients who undergo such conservative surgery is much improved. To address lymph node drainage, our approach is to perform unilateral superficial inguinal lymphadenectomy for those patients with unilateral vulvar cancer and to employ bilateral superficial inguinal lymphadenectomy for those with central vulvar cancers. The pilot study reported here is exploring a techniqueintraoperative lymphoscintigraphythat may allow us to limit the radicality of the lymph node dissection even further. The aim of this technique is to identify the sentinel node (or nodes) and to determine if the status of this node is truly predictive of the status of the other inguinal nodes. A second technique, which our group has pioneered, is lymphatic mapping, using injection of an isosulfan blue dye intraoperatively to identify sentinel nodes. Both techniques have derived from large studies of patients with melanoma. In fact, both techniques are warranted. If the positive predictive value is high enough, it will allow us to limit the lymph node procedure to resection of the sentinel nodes for patients in whom these nodes are negative and thereby reduce morbidity even more. As DeCesare et al note, there are potential advantages of their technique over lymphatic mapping. With intraoperative lymphoscintigraphy, the sentinel node can be located transcutaneously, and only a small incision can be used. Secondly, intraoperative lymphoscintigraphy quantitatively identifies sentinel nodes, allowing identification of more than one sentinel node. Larger trials conducted over the next few years will sort out these issues.