Inguinal sentinel node dissection versus standard inguinal node dissection in patients with vulvar cancer: A comparison of the size of metastasis detected in inguinal lymph nodes

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Abstract

Objective.

The emergence of sentinel lymph node (SLN) technology has provided the ability for an in depth pathologic evaluation for the detection of metastasis to lymph nodes through the use of ultra-staging. The SLN has been shown to be predictive of the metastatic status of its nodal basin. More recently, SLN dissections have been employed in the evaluation of the inguinal lymphatic basins in patients with vulvar malignancies. We hypothesize that the average size of metastasis detected in non-palpable inguinal lymph nodes is smaller when detected through the use of SLN dissection and ultra-staging versus complete inguinal node dissection (CND).

Methods.

This was an IRB approved retrospective study. The tumor registry database was searched to identify all patients diagnosed with a vulvar malignancy from 1990 to 2004. The records were reviewed to identify patients with inguinal lymph node metastasis. Only patients with non-palpable inguinal lymph nodes (metastasis 1 cm or less) were included in the analysis. All pathology slides were reviewed. The smallest metastatic foci of cells were measured from lymph nodes obtained through the traditional complete inguinal lymph node dissection (CND) and compared with the largest metastatic foci of cells detected in sentinel lymph node dissections. The mean size and standard deviation for each group was calculated and analyzed with a Mann–Whitney test.

Results.

There were 336 inguinal node dissections performed in patients identified with a vulvar malignancy. SLN dissections were performed in 52 groins and CND in 284 groins. Fifty-eight patients were found to have metastatic disease to the inguinal lymph nodes. Thirty of these patients had no evidence of lymph node metastasis on clinical exam or at the time of their EUA. There were 7 groins with metastasis detected through an SLN and 23 groins through a CND. The mean size of the metastatic foci detected in the SLN group was 2.52 mm (SD 1.55) and in the CND group was 4.35 mm (SD 2.63). This was not statistically significant (P = 0.109). However, when comparing the detection of micrometastasis in each set, there was a significant difference (P = 0.02) in the detection of the size of metastasis detected with smaller cluster of cells detected in the SLN group.

Conclusion.

SLN dissection with ultra-staging allows for a more extensive pathologic examination of lymph nodes and may allow for the detection of smaller tumor foci than the traditional pathological examination of lymph nodes obtained from a CND. The clinical implication of the detection of these micrometastasis and smaller metastasis remains to be determined.

Introduction

The American Cancer Society estimates that there will be 3870 new cases of vulvar cancer with 870 deaths from this disease for the year 2005 [1]. Traditionally, patients with vulvar malignancies underwent a radical vulvectomy with en bloc inguinofemoral lymphadenectomy. However, the complication rates associated with the classic approach were high, with up to 69% of patients experiencing chronic lymph edema and 85% wound breakdown [2]. More recently, in an attempt to reduce the morbidity associated with radical vulvar surgery, patients have been treated with radical wide local excisions or hemivulvectomies and superficial groin node dissections. A GOG study evaluating limited surgery with wide local excision and superficial groin node dissection reported a decrease in the rate of chronic lymph edema to 19% and wound infection and or separation to 29% [3]. The presence of inguinal lymph node metastasis is correlated with survival. The 5-year survival rate in women with negative inguinal lymph nodes for metastasis is 96% compared to 80% for patients with two positive nodes and 12% for those with three or more positive nodes [4]. Although all patients with invasive squamous cell carcinoma undergo complete inguinal lymph node dissection, only 27% will have nodal metastases and therefore 80% of women will have had a groin node dissection without any benefit and the exposure to the risk of the surgery [4].

Sentinel lymph node technology has provided the means for identifying the sentinel lymph node draining a tumor bed and provides for its removal through minimally invasive surgery. Inguinal sentinel lymph node dissection in vulvar cancer patients has been shown to be feasible and highly sensitive for the detection of metastatic disease to the inguinal nodal basin [5], [6], [7], [8], [9]. These studies have shown a nearly 100% identification rate of a SLN when lymphatic mapping with a radioactive tracer (Tc-99m sulfur colloid) is used in combination with blue dye. The negative predictive value of a negative sentinel lymph node in these studies has been shown to be 100% [5]. The utilization of a sentinel node dissection allows for an in-depth pathologic examination of the one or two sentinel lymph nodes through the use of pathologic ultra-staging allowing for the detection of micrometastasis [10].

We hypothesize that the average size of metastasis detected in non-palpable inguinal nodes is smaller when detected through the use of SLN dissection and ultra-staging versus complete inguinal node dissection.

Section snippets

Materials and methods

This was an IRB approved retrospective study. The Program in Women's Oncology tumor registry database at Women and Infants' Hospital was searched from 1990 to 2004 and identified 336 inguinal groin dissections in patients with a vulvar malignancy. Sentinel inguinal lymph node (SLN) dissections were performed in 52 groins and complete lymph node dissections (CND) alone in 284 groins. Patients with clinically suspicious lymph nodes (lymph nodes greater than 1 cm or palpable nodes) were excluded

Results

Three hundred and thirty six inguinal node dissections were performed in patients with primary vulvar malignancies. Thirty-four patients were identified that underwent SLN dissections through a prior SLN study and an ongoing SLN study. Eighteen of these patients had bilateral groin dissections totaling 52 groins. Of the 336 groin dissections, 284 underwent CND alone and 52 underwent SLN dissections. Only 66 groins were found to have nodal metastasis, 57 with CND, and 9 with SLN dissection. In

Discussion

The surgical treatment of vulvar cancer has evolved over the last few decades from radical en bloc resection of the vulva and groin nodes to radical wide local excision with separate inguinal node dissection. As well, the surgical approach to the evaluation of groin nodes has evolved from deep inguinal groin dissection to superficial inguinal groin dissections [11]. In a further attempt to decrease the morbidity associated with inguinal node dissection, sentinel lymph node technology has been

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