The overall incidence of inguinal-femoral lymph node metastases is reported to be about 32% (41,43,46–56) (Table 38.2). Metastases to pelvic nodes occur in about 12% of cases. Pelvic nodal metastases are rare (0.6%) in the absence of groin node involvement, but they occur in about 16% of cases with positive groin nodes (Table 38.2). The risk increases to 33% in the presence of clinically suspicious groin nodes and to 40% to 50% if there are three or more pathologically positive inguinal-femoral nodes (33,48,57–60). The incidence of lymph node
Table 38.2 Incidence of Lymph Node Metastases in Squamous Cell Carcinoma of the Vulva
N/A, data not available.
Figure 38.3 Inguinal-femoral lymph nodes. (From Berek JS, Hacker NF. Berek & Hacker’s Gynecologic Oncology. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2010:541, with permission.)
Table 38.3 Nodal Status in T1 Squamous Cell Carcinoma of the Vulva versus Depth of Stromal Invasion
From Berek JS, Hacker NF. Berek & Hacker’s Gynecologic Oncology. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins 2010:543, with permission.
metastases correlates positively with depth of invasion, as shown in Table 38.3. Hematogenous spread usually occurs late in the course of vulvar cancer and is rare in the absence of lymph node metastases.
Staging Initially, vulvar carcinoma was staged clinically based on tumor size and location, palpable regional lymph node status, and a limited search for distant metastases. The prognostic importance of the lymph node status is significant, but clinical assessment of the lymph nodes has limited accuracy. This led the Cancer Committee of FIGO to introduce a surgical staging system for vulvar cancer in 1988, which underwent several revisions, most recently in 2009, to provide better prognostic discrimination between stages and less heterogeneity within stages (31,61,62) (Table 38.4). The main changes are: 1.
While stage Ia remains unchanged as the only group of patients with a negligible risk of lymph node metastases, former stages I and II have been combined into stage Ib.
2.
The new stage II segregates patients whose tumors involve the lower adjacent perineal structures from those with positive lymph nodes.
3.
For stages III and IV, the number and morphology of the involved nodes are taken into account and the bilaterality of lymph nodes is discounted.
The new FIGO staging system was validated in 269 patients, 42% of whom were restaged (63). The number of positive nodes negatively correlated with survival, as did the presence of extracapsular growth. This study confirmed Gynecologic Oncology Group (GOG) and SEER data indicating that in patients with negative nodes, tumor size was not predictive of survival (62). This study confirmed reports demonstrating that, when corrected for the number of positive nodes, bilaterality of nodal metastases was not predictive of survival (64–67).
Paralleling the changes to the FIGO staging, the American Joint Committee on Cancer (AJCC) significantly modified the vulvar cancer tumor-node-metastasis (TNM) classification with the release of the 2009 edition of the AJCC Cancer Staging Manual (Table 38.4) (68).