Lymphatic mapping and sentinel node biopsy in squamous cell carcinoma of the vulva: Systematic review and meta-analysis of the literature

Highlights

• We performed a meta-analysis on the accuracy of sentinel node mapping in vulvar SCC.

• Pooled groin basis sentinel node detection rate was 84.6% [80.5–88] and pooled groin basis sensitivity was 92% [89–94].

• SN detection rate and sensitivity were related to mapping method, tumor location, and presence of palpable inguinal nodes.

Abstract

Objectives

We reviewed the available literature on the accuracy of sentinel node (SN) mapping in the inguinal lymph node staging of vulvar squamous cell carcinoma (SCC).

Methods

Medline and SCOPUS were searched by using “sentinel AND vulv*” as key words. Studies evaluating the accuracy of SN mapping in the inguinal lymph node staging of vulvar SCC were included if enough data could be extracted for calculation of detection rate and/or sensitivity. Only studies validated by inguinal lymph node dissection were included for sensitivity meta-analysis.

Results

Forty-nine studies were included in the systematic review. Pooled patient and groin basis SN detection rates were 94.4% [92.4–95.9] and 84.6% [80.5–88], respectively. Pooled patient and groin basis sensitivity were 92% [90–95] and 92% [89–94], respectively (or 8% [5–10] and 8% [6–11] false negative rates). Pooled negative predictive values were 97% [96–98] and 98% [97–99] for patient and groin basis analyses respectively. SN detection rate and sensitivity were related to mapping method (blue dye, radiotracer, or both) and location of the tumor (midline vs. lateral tumors). Patients with palpable inguinal nodes had lower detection rate and sensitivity.

Conclusion

SN mapping is an accurate method for inguinal node staging in vulvar SCC. Combining radiotracer and blue dye methods and excluding patients with palpable inguinal nodes result in the highest detection rate and sensitivity. For midline tumors possible false negative results of SN mapping should be taken into account.

Introduction

Vulvar cancer is a rare gynecological malignancy with an incidence of < 4000 cases/year in the United States [1]. The standard treatment for early stage vulvar cancer is surgical excision of the tumor and inguinal lymphadenectomy which can be unilateral or bilateral depending on the tumor location [2]. However, inguinal lymph node dissection is associated with considerable morbidity and can affect the quality of life of vulvar cancer patients [3]. It is also estimated that only a third of early stage vulvar cancer patients have regional lymph node metastases and the remainder of the patients would not benefit from inguinal lymph node dissection [4].

Sentinel node (SN) mapping is an approach to regional lymph node staging of solid tumors which can decrease the morbidity of lymph node dissection. This technique is currently in use in breast cancer, melanoma, and urological and gynecological malignancies [5], [6], [7]. Vulvar cancer is a suitable malignancy for the SN concept and since 1994 several groups have reported the accuracy of SN mapping for inguinal lymph node staging in this cancer [8]. The interest in SN mapping in vulvar cancer has increased considerably since the publication of GROINSS-V results [9], [10].

In the current study, we reviewed the available literature on SN mapping in vulvar cancer and presented the results in systematic review and meta-analysis formats.