Management of Pelvic Lymph Nodes In the past, pelvic lymphadenectomy was part of the routine surgery for invasive vulvar cancer. The incidence of pelvic lymph node metastasis is rare in the absence of groin node involvement, and a more selective approach is preferred (Table 38.2). Patients most prone to pelvic lymph node metastasis are those with three or more pathologically positive groin nodes (33,45,57,122). In addition to the number of nodes involved, the morphology of the positive groin nodes is of prognostic significance. As demonstrated in several studies, significant negative predictors of survival are the number of positive nodes, the size of the nodal metastasis, the proportion of the node replaced by tumor cells, and the presence of any extracapsular spread (65,70,75,76). In these patients, the pelvis requires treatment by radiation (discussed below). If a preoperative pelvic imaging study reveals bulky pelvic lymph nodes, resection of these nodes should be performed via an extraperitoneal approach prior to radiation because of the limited ability of external beam radiation therapy to sterilize bulky positive pelvic nodes.
Sentinel Lymph Node Studies Considerable investigation was conducted regarding the use of intraoperative lymphatic mapping using lymphoscintigraphy with technetium-99mlabeled nanocolloid or isosulfan blue dye to identify a sentinel node that would predict the presence or absence of regional nodal metastases (43,123–125). A systematic review of 29 small studies of 961 groins found lymphoscintigraphy to be the most accurate technique, with a pooled sensitivity and negative likelihood ratio of 97% and 0.12, respectively (126). Studies suggested that a sentinel node could be identified in most patients (127–129). A GOG study of 403 evaluable patients in whom 697 groins were assessed demonstrated that a sentinel node was successfully identified in 78.8% (67 of 85) of patients using blue dye only and in 96.2% (306 of 318) using combination of radiolocalization and blue dye, demonstrating the superiority of the combination of blue dye and radiocolloid over blue dye alone for sentinel node identification (130). The sensitivity of the sentinel node assessment is enhanced by ultrastaging using serial sectioning or immunohistochemistry to detect micrometastases (129,131–133).
The strong interest in the sentinel node concept lies in the desire to reduce the significant lifelong morbidity of lymphedema associated with a thorough inguinofemoral lymphadenectomy. Reliable identification of the sentinel node and forgoing full lymphadenectomy in patients with clinically nonsuspicious groin lymph nodes and a negative sentinel node may significantly reduce the number of patients who undergo unnecessary, extensive lymphadenectomy in the absence of disease. This is contingent upon a negative sentinel lymph node reliably predicting the absence of any other nodal metastases given the greater than 90% mortality associated with a groin recurrence.
The largest study published to date on the safety of the sentinel node procedure in vulvar cancer, GROINSS-V, included 403 assessable patients with a sentinel node procedure performed in 623 groins (Table 38.2) (129). Metastatic sentinel nodes were found in 26% of patients. In eight of 276 patients (3%) groin recurrences were diagnosed at a median follow-up time of 35 months. At the time of groin recurrence these patients all underwent bilateral inguinofemoral lymphadenectomy followed by chemoradiotherapy; six of the eight patients died of disease.