Research ArticleClinical Studies
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The Impact of Body Mass Index on Sentinel Lymph Node Identification in Endometrial Cancer

ROXANI DAMPALI, KONSTANTINOS NIKOLETTOS, IASON PSILOPATIS, EVANGELIA-GEORGIA KOSTAKI, ANDREAS JOHN PAPADOPOULOS, STEPHEN ATTARD-MONTALTO and OMER DEVAJA
Anticancer Research April 2025, 45 (4) 1575-1581; DOI: https://doi.org/10.21873/anticanres.17538

Abstract

Background/Aim: Endometrial cancer, a prevalent gynecologic malignancy, is often associated with obesity. Sentinel lymph node (SLN) mapping, a minimally invasive staging method, reduces the need for extensive lymphadenectomy, thereby minimizing surgical morbidity. However, the influence of body mass index (BMI) on SLN mapping outcomes is not fully understood. This study evaluated the relationship between BMI and SLN mapping success using data from a large and diverse patient cohort.

Patients and Methods: A retrospective study of 112 patients diagnosed with endometrial carcinoma was conducted. Patients were categorized into non-obesity (BMI <30 kg/m2) and obesity (≥30 kg/m2) groups. All underwent laparoscopic hysterectomy with SLN mapping using indocyanine green (ICG) dye. Statistical analysis was performed using univariable and multivariable logistic regression models.

Results: LN detection rates were 77.7% overall, with bilateral mapping achieved in 54.5% of patients. Mapping success was higher in the non-obesity group (59.7%) compared to the obesity group (49.1%; p=0.099). Mapping failure rates were notably higher in obese patients (30.9%) versus non-obese patients (14.0%) (p=0.099). Multivariable logistic regression analysis identified advanced cancer stage as a significant predictor of SLN biopsy positivity (adjusted odds ratio=30.2, p=0.002).

Conclusion: Obesity negatively impacts the technical success of SLN mapping in endometrial cancer, with lower bilateral detection rates and higher mapping failures observed in obese patients. These findings underscore the need for surgical strategies tailored to obese patients, such as optimizing tracer injection techniques, utilizing advanced imaging technologies, and incorporating preoperative planning to account for anatomical challenges. Addressing these factors may enhance SLN detection and improve staging accuracy in this high-risk population.

Keywords:

Introduction

Sentinel lymph node (SLN) mapping has revolutionized the surgical staging of endometrial cancer, particularly in patients with early-stage disease. By identifying the first lymph node that drains lymphatic fluid from the tumor, SLN mapping provides critical information about metastatic spread while minimizing the need for extensive lymphadenectomy. This approach significantly reduces complications such as lymphedema, nerve injury, and vascular damage. Additionally, the precise staging provided by SLN mapping aids in tailoring adjuvant therapy decisions, optimizing patient outcomes (1).

The adoption of indocyanine green (ICG) dye and near-infrared fluorescence imaging has further enhanced the feasibility and accuracy of SLN mapping. These advances allow for real-time visualization of lymphatic pathways, even in anatomically challenging cases (2). However, the effectiveness of SLN mapping can vary widely depending on patient-specific factors, including obesity. Obesity, defined as a body mass index (BMI) ≥30 kg/m2, presents unique challenges in gynecologic oncology. Elevated BMI is a well-established risk factor for endometrial cancer and contributes to altered lymphatic anatomy, increased adipose tissue, and technical difficulties during surgery (3).

The relationship between BMI and SLN mapping success remains controversial, with existing studies yielding mixed results. Some research suggests that obesity hinders tracer migration and visibility, reducing SLN detection rates (4, 5). Conversely, other studies indicate that advanced surgical techniques and imaging modalities may mitigate these challenges (6, 7). Despite these insights, there is limited consensus on how BMI impacts SLN mapping outcomes in endometrial cancer.

Expanding on this, obesity’s systemic impact, including its association with chronic inflammation and altered immune responses, may further complicate SLN mapping (8). Chronic low-grade inflammation, characteristic of obesity, can influence lymphatic function and the migration of tracer dyes, thereby affecting SLN detection rates (9). Furthermore, the technical complexity of surgery in obese patients, due to restricted operative fields and increased adipose tissue, underscores the multifactorial nature of these challenges (10).

This study aimed to bridge this gap by evaluating SLN mapping success rates across BMI categories. By analyzing data from patients undergoing laparoscopic surgery with SLN mapping, this research seeks to clarify the influence of BMI on mapping outcomes. The findings are expected to inform surgical planning, guide preoperative interventions, and contribute to the development of BMI-specific strategies for optimizing SLN identification.

Patients and Methods

Study design and population. This retrospective cohort study included patients diagnosed with endometrial carcinoma between 2020 and 2022. Inclusion criteria were histologically confirmed diagnosis of endometrial carcinoma and planned SLN mapping as part of surgical staging. Patients were categorized based on BMI into non-obesity (BMI <30 kg/m2) and obesity (≥30 kg/m2) groups. A total of 112 patients met the inclusion criteria, with 57 (50.9%) classified as non-obese and 55 (49.1%) as obese. The study was conducted at a single tertiary care center.

Additional variables were included to provide a comprehensive understanding of patient characteristics and surgical outcomes. These variables encompassed comorbidities (e.g., diabetes, hypertension), American Society of Anesthesiologists (ASA) physical status classification, and detailed histopathological findings such as tumor grade and lymphovascular space invasion. This broad dataset allowed for nuanced analysis of how BMI interacts with other clinical factors to influence SLN mapping success.

Surgical procedure. All patients underwent laparoscopic hysterectomy with SLN mapping using ICG dye. Cervical injections of a total of 2 ml of ICG were administered at the 3 and 9 o’clock positions. At each site, 0.5 ml were injected deep into the stroma and 0.5 ml submucosally. Near-infrared fluorescence imaging was utilized for real-time visualization of lymphatic pathways. Bilateral mapping success was defined as successful detection of SLNs in both hemipelves, while unilateral mapping indicated detection in only one hemipelvis. Mapping failure was defined as the absence of detectable SLNs.

Efforts were made to standardize the surgical procedure across cases to minimize variability. Surgeons adhered to established protocols for SLN mapping, including the use of a consistent tracer dose and injection technique. Additionally, all surgeries were performed by experienced gynecologic oncologists, reducing the potential for variability related to surgical expertise.

Data collection. Data collected included patient demographics (age, comorbidities, BMI, ASA status), surgical details (SLN mapping success, operative time, estimated blood loss), and histopathological findings (tumor grade and stage and SLN biopsy results). Comorbidities were assessed using the ASA physical status classification. SLN biopsy results were categorized as positive (micro- or macrometastases) or negative. The inclusion of operative details, such as the duration of surgery and estimated blood loss, provided additional context for understanding how BMI influences the technical aspects of SLN mapping.

Statistical analysis. Patient characteristics were summarized using mean/standard deviation or median/interquartile range (quantitative data), and absolute/relative frequencies (qualitative data). Shapiro–Wilk test was used to test for normality. Statistical analysis for simple comparisons of the relevant distributions across different categories of BMI (non-obesity and obesity) was carried out using Pearson’s chi-squared test/Fisher’s exact test or independent samples t-test/Mann–Whitney U-test. Univariable and multivariable logistic regression analyses were performed to estimate the determinants of SLN biopsy results. Specifically, a multivariable model was fit to 112 complete observations using the SLN biopsy result as the binary outcome variable, and age, BMI and cancer stage as possible explanatory variables. The outcomes were expressed as odds ratios (ORs) and adjusted odds ratios (aORs) along with their 95% confidence intervals (95%CI). A significance level of 0.05 was applied. All statistical analyses were performed on STATA 14-StataCorp LP (Stata Statistical Software: Release 14.2, StataCorp LLC, College Station, TX, USA).

Results

Patient demographics and clinical characteristics. Patient characteristics are presented in Table I. The study population included 112 patients, with a median age (SD) of 68.7 (10.0) years. The median BMI was 29 kg/m2 [interquartile range (IQR)=26-33]. The non-obesity group accounted for 50.9% (n=57) of the cohort, while 49.1% (n=55) of the patients were classified as obese. Comorbidities were more prevalent in the obesity group, with 74.6% (n=41) reporting at least one comorbidity compared to 45.6% (n=26) in the non-obesity group (p= 0.002). Age distribution was comparable between the two BMI groups, and no significant difference was observed between the mean age of obese and non-obese patients (p=0.588). However, the prevalence of ASA physical status III was notably higher in the obesity group, reflecting a greater burden of systemic disease (p=0.009).

View this table:
Table I.

Patient characteristics stratified by body mass index (BMI).

SLN detection and mapping success. Overall SLN detection rate was 77.7% (n=87), with differences observed between BMI groups. Bilateral mapping was achieved in 54.5% (n=61) of the patients, and in 59.7% (n=34) of non-obese patients and 49.1% (n=27) of obese patients (p= 0.099). Unilateral mapping was observed in 23.2% (n=26) of the cohort, while 30.9% (n=17) of obese patients experienced mapping failure compared to 14.0% (n=8) of non-obese patients. The median number of SLNs identified per patient was two (IQR=2-3), with no significant difference between BMI groups.

The impact of BMI on SLN mapping success was further explored through subgroup analyses. Among obese patients, those with higher BMI values demonstrated the highest failure rates, suggesting a dose-dependent relationship between BMI and mapping outcomes. Additionally, the presence of multiple comorbidities appeared to compound the challenges associated with obesity, further reducing SLN detection rates. Patients with higher class obesity also experienced longer operative times and increased technical difficulties during the procedure.

SLN biopsy results. Positive SLN biopsy results were reported in 14.3% (n=16) of patients, with similar rates across BMI groups (17.5% in non-obese vs. 10.9% in obese; p=0.316). Advanced cancer stage was strongly associated with positive SLN findings (Table II). Multivariable logistic regression analysis identified stage II/III endometrial cancer as a significant predictor of SLN positivity (aOR=30.2, p=0.002) (Table II). BMI was not revealed as a statistically significant predictor of SLN biopsy outcome in the final model (p=0.581) (Table II). Positive SLN findings were more likely in patients with higher tumor grades and lymphovascular space invasion, irrespective of BMI.

View this table:
Table II.

Univariable and multivariable logistic regression analysis estimates using the result of the sentinel lymph node (SLN) biopsy as the outcome variable (determinants of the SLN biopsy result).

Surgical outcomes. Operative time was longer in the obesity group, averaging 163.8 [standard deviation (SD)=41.7] min compared to 152.9 (SD=32.3) min in the non-obesity group (p=0.125). Estimated blood loss was comparable between BMI groups (obesity group: 100 vs. non-obesity group: 150 ml) (p=0.273). Subgroup analyses of surgical outcomes indicated that longer operative times were associated with higher BMI categories and greater comorbidity burdens. Despite these challenges, there were no significant differences in perioperative complications between BMI groups.

Discussion

The results of this study show a relationship between BMI and the success of SLN mapping in patients with endometrial cancer. Specifically, SLN detection rates decreased as BMI increased, with bilateral mapping success rates of 59.7% in non-obese and 49.1% in obese patients. Mapping failure rates were higher among obese patients (30.9%) compared to non-obese patients (14.0%). Multivariable logistic regression analysis could, however, not confirm BMI as an independent predictor of SLN positivity. These findings may underscore the challenges posed by elevated BMI in achieving successful SLN mapping, without however being statistically significant probably due to the small patient sample size.

When compared to existing literature, our findings align with previous studies demonstrating decreased SLN mapping success in patients with higher BMI. For instance, studies by Fennimore et al. and Secord et al. reported similar trends, emphasizing that excessive adipose tissue interferes with tracer migration and visibility (4, 11, 12). However, certain studies utilizing advanced imaging techniques have suggested ways to mitigate these challenges, indicating that tailored surgical strategies might improve outcomes in this population (13, 14). Our data corroborate these findings but also highlight that the challenges persist despite technological advancements, particularly in cases of severe obesity.

Several factors may explain the observed relationship between BMI and mapping success. Increased adiposity may distort lymphatic anatomy, impairing tracer migration to the SLN (9). Additionally, the thicker tissue planes in obese patients can obscure visualization during near-infrared imaging. These anatomical and physiological challenges are compounded by technical difficulties during surgery, including limited workspace and increased operative times, which may further reduce mapping accuracy (15). These factors collectively contribute to the higher failure rates observed in obese patients.

The strengths of this study include a well-defined cohort, consistent surgical protocols, and comprehensive data collection. However, there are notable limitations. This study was conducted in a single center, potentially limiting the generalizability of the findings. Additionally, the retrospective design introduces the possibility of selection bias. Variability in surgeon experience and patient comorbidities may also have influenced outcomes, though efforts were made to standardize the surgical approach. Future prospective, multicenter studies are needed to validate these findings and address the inherent limitations of retrospective analyses.

Future research should focus on innovative approaches to improve SLN mapping in obese patients. Investigating alternative tracer methods, such as hybrid tracers combining fluorescence and radiolabeling, may enhance detection rates. Preoperative imaging techniques to better delineate lymphatic pathways could also play a critical role. Moreover, developing standardized protocols that account for BMI-specific challenges and assessing their effectiveness through randomized controlled trials could provide valuable insights. Addressing these areas will be essential to optimize surgical outcomes for obese patients with endometrial cancer.

Conclusion

BMI seems to play a role in the success of SLN mapping for endometrial cancer. Lower bilateral mapping success and higher failure rates are observed in obese patients, necessitating targeted approaches to improve detection rates. These findings underscore the importance of personalized surgical strategies in managing obese patients with endometrial cancer.

Footnotes

  • Authors’ Contributions

    RD and KN equally contributed to the conception, design, and drafting of the article. EMK performed the statistical analysis. AJP, SAM, and OD carried out the surgical procedures. IP contributed to the refinement and critical review of the manuscript. AP and SM also revised the manuscript for important intellectual content. OD provided supervision and final approval of the manuscript. All Authors have read and approved the final version of the manuscript.

  • Conflicts of Interest

    The Authors declare that there are no conflicts of interest regarding the publication of this article.

  • Funding

    No funding was received for the completion of this study or the preparation of this manuscript.

  • Received February 13, 2025.
  • Revision received February 28, 2025.
  • Accepted March 4, 2025.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY-NC-ND) 4.0 international license (https://creativecommons.org/licenses/by-nc-nd/4.0).

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The Impact of Body Mass Index on Sentinel Lymph Node Identification in Endometrial Cancer
ROXANI DAMPALI, KONSTANTINOS NIKOLETTOS, IASON PSILOPATIS, EVANGELIA-GEORGIA KOSTAKI, ANDREAS JOHN PAPADOPOULOS, STEPHEN ATTARD-MONTALTO, OMER DEVAJA
Anticancer Research Apr 2025, 45 (4) 1575-1581; DOI: 10.21873/anticanres.17538
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