Omitting lymphadenectomy in obese endometrial cancer patients undergoing sentinel lymph node mapping: when more is less

Abstract

<h3>Objectives:</h3> Obese patients present unique surgical and technical challenges to their surgeons and anesthesiologists given their multiple comorbidities, difficult anatomy, and excessive weight. Thus, any surgical procedure that prolongs surgical time and potentially increases risk for complications in this population, needs to be carefully evaluated and minimized.The aim of this study is to evaluate the feasibility of sentinel lymph node (SLN) mapping in obese endometrial cancer patients, and to determine whether omitting lymph node dissection (LND) from surgical staging where SLN sampling is performed, impacts oncologic outcomes. <h3>Methods:</h3> Between December 2007 and August 2017, 722 patients with uterine cancer underwent surgical staging in our institution. We excluded patients with sarcomas (n=32), patients with stage 4 disease (n=9), patients who received neoadjuvant therapy (n=5) and patients whose body mass index (BMI) was below 35.0 kg/m² (n=453). The approach for LND at our center changed over the years: all surgeries from January 2008 to August 2014 included bilateral pelvic LND, with para-aortic LND at the surgeon's discretion (LND±SLN cohort). In addition to LND, all consecutive patients from December 2010 to August 2014 underwent SLN mapping with a cervical injection. With the establishment of SLN mapping algorithm feasibility, patients operated from August 2014 to August 2017 went through SLN mapping without LND (SLN cohort). <h3>Results:</h3> Out of 223 patients with a median BMI of 40.6 kg/m², 140 patients underwent LND (± SLN) and 83 patients underwent SLN. The median operative time for surgical staging in SLN only group was shorter in 47.5 minutes than for patients in the LND±SLN group (190.5 minutes (108-393) vs. 238 minutes (131-440), respectively, (p<0.001)), and they had reduced estimated blood loss (EBL) compared to the LND±SLN group (30 ml (0-300) vs. 40 ml (0-800ml), P=0.03). At a 24 months' follow-up cut-off, 98% of the patients were alive and 95.5% were free of disease, without significant differences in OS, DSS and PFS between the two groups (p=0.7, p=0.8 and p=0.4, respectively).Overall, 171 patients underwent SLN biopsy (±LND) and stratified by the tracer used for mapping (ICG versus blue dye). The ICG injected group had higher successful mapping and bilateral detection rates (92.8% vs 71.7%, p<0.001 and 80.2% vs 43.3%, p<0.001, respectfully). <h3>Conclusions:</h3> The obese population is at increased risk for intraoperative and postoperative complications associated with prolonged operative time from secondary to challenges in the surgical and anesthesia process. The advantage of minimizing the surgery towards SLN approach, as reflected in our results by shorter operative time and minimal bleeding is of particular importance in this set of patients. Omitting LND from surgical staging where SLN is performed was not associated with inferior survival outcomes. Given the higher successful detection and metastatic nodes rates with ICG and NIR fluorescence imaging compared to previously reported rates with blue dye based SLN, ICG should be the dye of choice in obese and morbid obese EC patients. Future studies should focus on molecular stratification of obese EC patients into risk groups for nodal disease, selecting patients for LND in cases of failed mapping.