The SENTIREC-endo study - Risks and benefits of a national adoption of sentinel node mapping in low and intermediate risk endometrial cancer

SENECA study: staging endometrial cancer based on molecular classification

OBJECTIVE

Management of endometrial cancer is advancing, with accurate staging crucial for guiding treatment decisions. Understanding sentinel lymph node (SLN) involvement rates across molecular subgroups is essential. To evaluate SLN involvement in early-stage (International Federation of Gynecology and Obstetrics 2009 I-II) endometrial cancer, considering molecular subtypes and new European Society of Gynaecological Oncology (ESGO) risk classification.

METHODS

The SENECA study retrospectively reviewed data from 2139 women with stage I-II endometrial cancer across 66 centers in 16 countries. Patients underwent surgery with SLN assessment following ESGO guidelines between January 2021 and December 2022. Molecular analysis was performed on pre-operative biopsies or hysterectomy specimens.

RESULTS

Among the 2139 patients, the molecular subgroups were as follows: 272 (12.7%) p53 abnormal (p53abn, 1191 (55.7%) non-specific molecular profile (NSMP), 581 (27.2%) mismatch repair deficient (MMRd), 95 (4.4%) POLE mutated (POLE-mut). Tracer diffusion was detected in, at least one side, in 97.2% of the cases; with a bilateral diffusion observed in 82.7% of the cases. By ultrastaging (90.7% of the cases) or one-step nucleic acid amplification (198 (9.3%) of the cases), 205 patients were identified with affected sentinel lymph nodes, representing 9.6% of the sample. Of these, 139 (67.8%) had low-volume metastases (including micrometastases, 42.9%; and isolated tumor cells, 24.9%) while 66 (32.2%) had macrometastases. Significant differences in SLN involvement were observed between molecular subtypes, with p53abn and MMRd groups having the highest rates (12.50% and 12.40%, respectively) compared with NSMP (7.80%) and POLE-mut (6.30%), (p=0.004); (p53abn, OR=1.69 (95% CI 1.11 to 2.56), p=0.014; MMRd, OR=1.67 (95% CI 1.21 to 2.31), p=0.002). Differences were also noted among ESGO risk groups (2.84% for low-risk patients, 6.62% for intermediate-risk patients, 21.63% for high-intermediate risk patients, and 22.51% for high-risk patients; p<0.001).

CONCLUSIONS

Our study reveals significant differences in SLN involvement among patients with early-stage endometrial cancer based on molecular subtypes. This underscores the importance of considering molecular characteristics for accurate staging and optimal management decisions.

Prevalence and size of pelvic sentinel lymph node metastases in endometrial cancer

AIM OF THE STUDY

To assess the association of prevalence and size of pelvic sentinel node (SLN) metastases with risk factors in endometrial cancer (EC).

PATIENTS AND METHODS

Between June 2014 and January 2024 consecutive women with a uterine confined EC undergoing robotic surgery including detection of pelvic SLNs at a University Hospital were included. An anatomically based algorithm utilizing Indocyanine green (ICG) as tracer was adhered to. Ultrastaging and immunohistochemistry (IHC) was applied on all SLNs. The prevalence and size of SLN metastases was assessed with regards to pre- and postoperative histologic types and myometrial invasion estimates.

RESULTS

Of 1101 included women 72.6 % (759/1045) had low-grade, 7.6 % (79/1045) high-grade endometroid cancer and 19.8 % (207/1045) non-endometroid cancer. SLN-metastases were present in 174/1045 (16.6 %) women; 9.8 % of preoperatively presumed low-grade endometroid uterine stage 1A (6.4 % of low-grade stage 1A at final histology) and in 58.3 % and 47.8 % respectively in women with high-grade endometroid and non-endometroid uterine stage 1B cancer. In low-grade EC 45/95 (47.4 %) had only isolated tumor cells (ITC) in SLNs compared with 15/78 (19.2 %) in high-grade or non-endometroid cancer (p < .0001) CONCLUSION: This large population-based study, applying a consequent SLN-algorithm over time, provides important detailed information on the risk for, and size of, SLN metastases within risk groups of EC. The 9.8 % risk for metastases in women with presumed low grade uterine stage 1A endometrioid EC motivates detection of SLNs within this subgroup. The proportion of ITCs in SLNs was significantly lower in higher risk histologies.

Risks and benefits of sentinel lymph node evaluation in the management of endometrial intraepithelial neoplasia

INTRODUCTION

Endometroid intraepithelial neoplasia (EIN) is a premalignant lesion to endometrial cancer. Increasing number of gynecologic oncologists are performing sentinel lymph node (SLN) evaluation during hysterectomy for EIN to ensure complete staging if there is cancer on the final specimen. However, there are no clear guidelines and the benefits and risks to performing SLN evaluation for EIN patients are unclear.

AREAS COVERED

This narrative review examines the advantages and disadvantages of SLN evaluation for EIN patients and provides an algorithm to assist clinicians in selectively applying the procedure for maximal patient benefit. Relevant articles up to March 2024 were obtained from a PubMed search on SLN use with endometrial pathology.

EXPERT OPINION

Sentinel lymph node evaluation for patients with EIN is safe, feasible, and particularly important for the approximately 10% of patients with high-risk endometrial carcinoma on final pathology. However, as most diagnosed carcinomas are low-risk, SLN evaluation would have limited oncologic benefit. While SLN assessment may overtreat most patients with EIN, a significant minority of patients will be improperly staged. We propose an algorithm highlighting the importance of maximal preoperative endometrial sampling and stratifying patients via risk factors to selectively identify those who would benefit most from SLN evaluation.

Incidence of sentinel lymph node metastases in apparent early-stage endometrial cancer: a multicenter observational study

OBJECTIVE

Ultrastaging is accurate in detecting nodal metastases, but increases costs and may not be necessary in certain low-risk subgroups. In this study we examined the risk of nodal involvement detected by sentinel lymph node (SLN) biopsy in a large population of apparent early-stage endometrial cancer and stratified by histopathologic characteristics. Furthermore, we aimed to identify a subgroup in which ultrastaging may be omitted.

METHODS

We retrospectively included patients who underwent SLN (with bilateral mapping and no empty nodal packets on final pathology) ± systematic lymphadenectomy for apparent early-stage endometrial cancer at two referral cancer centers. Lymph node status was determined by SLN only, regardless of non-SLN findings. The incidence of macrometastasis, micrometastasis, and isolated tumor cells (ITC) was measured in the overall population and after stratification by histotype (endometrioid vs serous), myometrial invasion (none, <50%, ≥50%), and grade (G1, G2, G3).

RESULTS

Bilateral SLN mapping was accomplished in 1570 patients: 1359 endometrioid and 211 non-endometrioid, of which 117 were serous. The incidence of macrometastasis, micrometastasis, and ITC was 3.8%, 3.4%, and 4.8%, respectively. In patients with endometrioid histology (n=1359) there were 2.9% macrometastases, 3.2% micrometastases, and 5.3% ITC. No macro/micrometastases and only one ITC were found in a subset of 274 patients with low-grade (G1-G2) endometrioid endometrial cancer without myometrial invasion (all <1%). The incidence of micro/macrometastasis was higher, 2.8%, in 708 patients with low-grade endometrioid endometrial cancer invading <50% of the myometrium. In patients with serous histology (n=117), the incidence of macrometastases, micrometastasis, and ITC was 11.1%, 6.0%, and 1.7%, respectively. For serous carcinoma without myometrial invasion (n=36), two patients had micrometastases for an incidence of 5.6%.

CONCLUSIONS

Ultrastaging may be safely omitted in patients with low-grade endometrioid endometrial cancer without myometrial invasion. No other subgroups with a risk of nodal metastasis of less than 1% have been identified.

Low-Volume Metastases in Apparent Early-Stage Endometrial Cancer: Prevalence, Clinical Significance, and Future Perspectives

Endometrial cancer (EC) is the most diagnosed gynecologic malignancy, and its incidence and mortality are increasing. The prognosis is highly dependent on the disease spread. Surgical staging includes retroperitoneal evaluation to detect potential lymph node metastases. In recent years, systematic lymphadenectomy has been replaced by sentinel lymph node (SLN) biopsy and ultrastaging, allowing for the detection of macrometastases, micrometastases, and isolated tumor cells (ITCs). Micrometastases and ITCs have been grouped as low-volume metastases (LVM). The reported prevalence of LVM in studies enrolling more than one thousand patients with apparent early-stage EC ranges from 1.9% to 10.2%. Different rates of LVM are observed when patients are stratified according to disease characteristics and their risk of recurrence. Patients with EC at low risk for recurrence have low rates of LVM, while intermediate- and high-risk patients have a higher likelihood of being diagnosed with nodal metastases, including LVM. Macro- and micrometastases increase the risk of recurrence and cause upstaging, while the clinical significance of ITCs is still uncertain. A recent meta-analysis found that patients with LVM have a higher relative risk of recurrence [1.34 (95% CI: 1.07-1.67)], regardless of adjuvant treatment. In a retrospective study on patients with low-risk EC and no adjuvant treatment, those with ITCs had worse recurrence-free survival compared to node-negative patients (85.1%; CI 95% 73.8-98.2 versus 90.2%; CI 95% 84.9-95.8). However, a difference was no longer observed after the exclusion of cases with lymphovascular space invasion. There is no consensus on adjuvant treatment in ITC patients at otherwise low risk, and their recurrence rate is low. Multi-institutional, prospective studies are warranted to evaluate the clinical significance of ITCs in low-risk patients. Further stratification of patients, considering histopathological and molecular features of the disease, may clarify the role of LVM and especially ITCs in specific contexts.

Identifying safe diagnostic algorithms for sentinel lymph node mapping in high-risk endometrial cancer: The SENTIREC-endo study

INTRODUCTION

It is unclear if sentinel node (SLN) mapping can replace pelvic- (PLD) and paraaortic lymphadenectomy (PALD) for high-risk endometrial cancer (EC). A diagnostically safe surgical algorithm, taking failed mapping cases into account, is not defined. We aimed to investigate the diagnostic accuracy of SLN mapping algorithms in women with exclusively high-risk EC.

METHODS

We undertook a prospective national diagnostic cohort study of SLN mapping in women with high-risk EC from March 2017 to January 2023. The power calculation was based on the negative predictive value (NPV). Women underwent SLN mapping, PLD and PALD besides removal of suspicious and any FDG/PET-positive lymph nodes. Accuracy analyses were performed for five algorithms.

RESULTS

170/216 included women underwent SLN mapping, PLD and PALD and were included in accuracy analyses. 42/170 (24.7%) had nodal metastasis. The algorithm SLN and PLD in case of failed mapping, demonstrated a sensitivity of 86% (95% CI 74-100) and an NPV of 96% (95% CI 91-100). The sensitivity increased to 93% (95% CI 83-100) and the NPV to 98% (95% CI 94-100) if PLD was combined with removal of any PET-positive lymph nodes. Equivalent results were obtained if PLD and PALD were performed in non-mapping cases; sensitivity 93% (95% CI 83-100) and NPV 98% (95% CI 95-100).

CONCLUSION

SLN-mapping is a safe staging procedure in women with high-risk EC if strictly adhering to a surgical algorithm including removal of any PET-positive lymph nodes independent of location and PLD or PLD and PALD in case of failed mapping.