The diagnostic role of lymph node dissection in early-stage endometrial cancer
LND is used in the surgical staging of EC. The International Federation of Gynaecology and Obstetrics (FIGO) classification system is the most widely accepted method for EC staging. It was refined in 2009 based on advancements in the literature (Table 2)(18).
Table 2 | This table was adapted by the authors from Table 3 of The International Federation of Gynaecology and Obstetrics (FIGO) classification system(19). EC = endometrial cancer. *Either G1, G2 or G3.
A key diagnostic role of LND in EC is to guide adjuvant treatment(20). The ASTEC study (A Study of the Treatment of Endometrial Cancer) (2009) is one of two randomised controlled studies in this field. Given the low node-positivity rate in this study, a large number of patients would be required for adequate power. However, this requirement was not fulfilled as out of 683 patients in the standard surgery group and 686 in the LND group, only 9 and 54 patients respectively, were node-positive. The ASTEC study concluded that LND cannot be recommended in stage I EC unless it affects adjuvant therapy(20). They therefore did not resolve an important clinical question: do higher risk patients benefit from LND?
A review by Todo et al(18) highlighted the importance of stratifying patients by risk and not staging alone because within each stage, different risk groups have different outcomes to treatments. The ESMO-ESGO-ESTRO 2016 consensus recognises this importance. It does so by incorporating other pathological prognostic features alongside FIGO 2009 to identify patients at risk of LN metastasis or recurrence(5). During diagnostic investigations, clinical and aforementioned features are gathered and collated. This is used to stratify patients into risk groups. The defining features and management recommendations for early-stage EC based on ESMO-ESGO-ESTRO 2016 are summarised by risk group in Table 3.
The features that define “low-risk” are varied within the literature, resulting in differences in how surgical management and adjuvant therapies were tailored, as seen in this systematic review(21). For the low-risk group, FIGO 2009(19) and National Comprehensive Cancer Network (NCCN) 2016 identify tumour diameter as an important pathological feature in addition to those in ESMO-ESGO-ESTRO 2016 (Table 3). A 2017 study also incorporated tumour size of less than 2cm into its risk stratification system, however this was not found to be an independent prognostic factor(12,22). Without a standardised approach, this poses difficulty both in the clinical setting and when comparing clinical trials.
Table 3 | Summary of ESMO-ESGO-ESTRO Consensus Conference 2016 risk stratification system for early-stage endometrial cancer. The figure was created by authors based on ESMO-ESGO-ESTRO Consensus Conference 2016(5). Depth of myometrial invasion: Stage IA = Superficial <50%; Stage IB = Deep ≥50%. Cervical involvement: Stage II. EBRT = external beam radiation therapy.