Sentinel node mapping vs. sentinel node mapping plus back-up lymphadenectomy in high-risk endometrial cancer patients: Results from a multi-institutional study

OBJECTIVE

Sentinel node mapping (SLN) has replaced lymphadenectomy for staging surgery in apparent early-stage low and intermediate risk endometrial cancer (EC). Only limited data about the adoption of SNM in high risk EC is still available. Here, we evaluate the outcomes of high-risk EC undergoing SNM (with or without back-up lymphadenectomy).

METHODS

This is a multi-institutional international retrospective study, evaluating data of high-risk (FIGO grade 3 endometrioid EC with myometrial invasion >50% and non-endometrioid histology) EC patients undergoing SNM followed by back-up lymphadenectomy and SNM alone.

RESULTS

Chart of consecutive 196 patients were evaluated. The study population included 83 and 113 patients with endometrioid and non-endometrioid EC, respectively. SNM alone and SNM followed by back-up lymphadenectomy were performed in 50 and 146 patients, respectively. Among patients having SNM alone, 14 (28%) were diagnosed with nodal disease. In the group of patients undergoing SNM plus back-up lymphadenectomy 34 (23.2%) were diagnosed with nodal disease via SNM. Back-up lymphadenectomy identified 2 (1%) additional patients with nodal disease (in the para-aortic area). Back-up lymphadenectomy allowed to remove adjunctive positive nodes in 16 (11%) patients. After the adoption of propensity-matched algorithm, we observed that patients undergoing SNM plus back-up lymphadenectomy experienced similar disease-free survival (p = 0.416, log-rank test) and overall survival (p = 0.940, log-rank test) than patients undergoing SLN alone.

CONCLUSIONS

Although the small sample size, and the retrospective study design this study highlighted that type of nodal assessment did not impact survival outcomes in high-risk EC. Theoretically, back-up lymphadenectomy would be useful in improving the removal of positive nodes, but its therapeutic value remains controversial. Further prospective evidence is needed.

Abstract LB-268: Detection of TP53 clonal mutations in PAP test collected up to six years prior to high-grade serous epithelial ovarian cancer diagnosis

Background: The low five-years survival rate of High Grade Serous Epithelial Ovarian Cancer (HGS-EOC) is mainly related to late diagnosis. The anticipation of diagnosis constitutes a crucial step to increase the curability of this disease.

Aim: This study explores an innovative potential HGS-EOC screening approach exploiting PAP tests routinely executed for cervical cancer surveillance and the presence of TP53 clonal alterations in almost all HGS-EOCs. Indeed, it investigates the possibility to detect, in DNA purified from PAP tests collected by patients years before the diagnosis, the clonal pathogenic TP53 variant identified in the matched primary tumor biopsy.

Study Design: This retrospective and longitudinal study was conducted on 17 advanced HGS-EOC patients. Next Generation Sequencing (NGS) was used to identify TP53 clonal mutations in tumor tissue. The presence of these TP53 variants was then assessed by the droplet digital PCR (ddPCR) in DNA purified from all available patients' PAP tests executed up to almost six years before diagnosis.

Results: In each patient, one TP53 clonal somatic variant was identified by NGS in the primary tumor samples (Table 1). The presence of the TP53 variant was then investigated by ddPCR in matched Pap tests. In twelve out of 17 patients the TP53 variant was detectable in PAP tests collected within six months before diagnosis (T1) or earlier (T2, T3 and T4) (Table 1). For two patients (21561 and 21521) more PAP tests collected at different time before diagnosis (two/four and three/six years before diagnosis, respectively) were analyzed and the TP53 clonal variant was detected at all time points (Table 1).

Table 1:NGS and ddPCR resultsPatient IDTP53 mutationNGS tumor mutated %PAP test (months before surgery)T1(0-6)T2(7-24)T3(25-48)T4(≥49)Time intervalddPCR mutated %Time intervalddPCR mutated %Time intervalddPCR mutated %Time intervalddPCR mutated %21561c.818G>A65.010.20.24--250.21490.2621585c.817C>T40.94--11.30.21----21567c.281C>A71.9830.07------21587c.469G>T15.122ND------21586c.818G>A79.73--19.30.15----21569c.574C>T62.365.21.18------21624c.820G>T86.72----37.50.0465.3ND21570c.844C>T89.190.32.62------21627c.425_427del76.040.72.4------21640c.993+2T>G70.68--8ND----21507c.1025G>C91.23--9.20.06----21635c.844C>T66.241.3ND------21549c. 393_395del54.06----31.2ND65.3ND21521c. 722 C>G61.15----26.70.0567.30.0721654c.586 C>T49.354.70.09------21665c. 393_395del45.34----37.6ND--21683c.602 T>A33.42--18.50.06----ND Not Detected

Conclusion: This study demonstrates that non-invasive early molecular diagnosis of HGS-EOC is feasible through detection of TP53 clonal mutations in the DNA purified from PAP tests performed during cervical cancer screening. Further developments in highly sensitive molecular approaches could dramatically improve early diagnosis of HGS-EOC.

Citation Format: Chiara Pesenti, Lara Paracchini, Martina Delle Marchette, Luca Beltrame, Tommaso Bianchi, Tommaso Grassi, Alessandro Buda, Fabio Landoni, Lorenzo Ceppi, Cristina Bosetti, Maria Chiara Paderno, Marco Adorni, Debora Vicini, Patrizia Perego, Biagio Eugenio Leone, Sergio Marchini, Robert Fruscio, Maurizio D'Incalci. Detection of TP53 clonal mutations in PAP test collected up to six years prior to high-grade serous epithelial ovarian cancer diagnosis [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-268.