**Abstract**

Lymphadenectomy, for early stages of endometrial cancer (EC), provides a low detection rate of lymphatic metastasis, without having demonstrated a therapeutic effect; so that the collection and histological analysis of the sentinel lymph node (SLN) might be an alternative to lymphadenectomy. The contribution of SLN to surgical staging represents a change in the paradigm of lymphadenectomy in EC, being an intermediate approach between not assessing the condition of the lymph nodes and complete pelvic and paraaortic dissection. Accurate identification of the main uterine drainage pathway increases the likelihood of detecting metastases during lymphatic mapping. In addition, pathological assessment by the ultrastaging of the SLN is the most important advance in the SLN biopsy (SLNB) technique. The application of the SLNB presumes a decrease in surgical and long-term morbidity, with an increase in the detection of lymphatic metastasis, mainly at the expense of detecting low tumour volume, selecting the group of patients that would benefit from a modification in adjuvant therapy. The SLNB can be established as an oncologically safe and effective method in the surgical staging of early-stage EC. Prospective studies are required to determine optimal behaviour and prognosis in the detection of low-volume metastases.

**Keywords:** endometrial cancer, lymphatic mapping, predictive value of tests, sentinel lymph node biopsy, ultrastaging

#### **1. History and concept**

The origins of lymphatic mapping date back more than 100 years, when Sappey injected mercury into the skin of cadavers to delineate the skin's lymphatic pathways [1, 2]. Lymphoscintigraphy was described by Shearman and Ter-Pogossian in 1953, both of whom confirmed Sappey's hypothesis that lymphatic drainage occurs in an orderly and predictable manner [2].

The origin of lymphatic drainage of tumours and its implications for surgical staging are traced back to 1850 with the studies of Virchow and Haldsted on radical axillary lymphadenectomy for breast cancer.

The contribution of SLN to surgical staging represents a change in the paradigm of lymphadenectomy in EC. SLN represented an intermediate approach between not assessing the condition of the lymph nodes and complete pelvic and paraaortic dissection [3, 4]. The accurate identification of the main uterine drainage pathway increases the likelihood of detecting metastases during lymphatic mapping [5].

This information, provided by SLN, will change the therapeutic approach, with a potential benefit in the prognosis, both in survival and quality of life [6].

cranially over the course of the mesoureter. In these cases, SLN is usually

3.A third pathway has been described, the *infundibular pelvic*, but it is very rare except with fundal injections. This pathway has mainly fundal drainage

Three main areas of injection on the uterus have been described: (1) corporal,

1.**Corporal**: The injection can be subserosal or transmyometrial, in the anterior wall, posterior wall or uterine fundus. Corporal injection by laparotomy, using blue dye, was the first technique described. Subserosal injections have the drawback of multiple injections [12] and anatomical distortion when dealing with fibroids [13]. These injections might not be representative of the lesion if

parametrial drainage, subserosal injections have a detection rate of 75–91% and bilaterality of 80%, which is lower than that of cervical injections (p = 0.005) [11], although the former has superior paraaortic drainage (31–40%) [14].

the tumour does not infiltrate the uterine fundus. Due to the lack of

2.**Endometrial**: Intratumoural and peritumoural infiltration have superior validity due to the proximity to the tumour lesion [10, 15]. The disadvantages of this injection pathway are lower rates of bilaterality and paraaortic drainage, which are determined by the location and size of the lesion [16]. Hysteroscopic injections achieve detection rates of 69–80% [17, 18], with greater paraaortic drainage (up to 60%) [15], without having shown superiority against other injection pathways [19]. The hysteroscopic injection procedure is a more complex and uncomfortable technique for the patient. Recent studies have concluded that hysteroscopic injections do not have a correlation between the location of the SLN and the location of the tumour in the uterine cavity [20]. The risk of tumour dissemination to the abdominal cavity has been shown to be irrelevant [21]. Clamping the tubes before or after the injection of the dye

In 2013, the group from the Hospital Clinic of Barcelona published their results

Metastatic involvement of SLN in high-risk histology appeared in 24 patients, with paraaortic extension in 30% of cases. The authors concluded that the TUMIR technique is representative of tumour drainage and can be a promising detection method in high-risk histology, although further studies on the technique are needed [7]. The TUMIR technique has shown no differences compared with hysteroscopic

3.**Cervical**: The cervical injection is the modality most often reported in studies [23]. The technique is reproducible, because the uterine cervix is accessible and

with the transvaginal ultrasound-guided myometrial injection of radiotracer (TUMIR) technique, injecting 148 MBq of 99mTc-albumin nanocolloid (in a volume of 8 mL) in the anterior and posterior peritumoural uterine wall, with migration of 90.5% and laparoscopic identification of 74.3%. The drainage was pelvic in 87.2%, pelvic and paraaortic in 45.4% and exclusively paraaortic in 12.8% of cases.

interferes with the detection rate by decreasing it [22].

(2) endometrial and (3) cervical. Each area has been assessed with various approaches: hysteroscopic, laparoscopic and ultrasound-guided transvaginal and

observed in the internal iliac, common iliac or presacral region.

towards the broad ligament and paraaortic chain [11].

*Role of Sentinel Node Biopsy in Endometrial Cancer DOI: http://dx.doi.org/10.5772/intechopen.89949*

**2.2 Injection techniques**

injections (p = 0.2) [7].

**175**

even with combined techniques.
