Body Mass Index May be Predictive of Sentinel Lymph Node Mapping Failure in Apparent Early-Stage Endometrial Cancer

Body mass index (BMI) appeared to be predictive of sentinel lymph node mapping failure and could decrease overall detection rate among those with apparent early-stage endometrial cancer, according to data from the ObeLyX study published in Gynecologic Oncology.

For every 5 units of BMI, patients had a 1.156-fold increase in risk of mapping failure (OR, 1.156; 95% CI, 1.033-1.294; P = .012). Patients also had a corresponding decrease in bilateral mapping (OR, 0.865; 95% CI, 0.773-0.968; P = .012) and overall decision rate based on BMI (OR, 0.785; 95% CI, 0.670-0.920; P = .003). Patients who were obese were surgically understaged in 9.4% of cases vs those who were not at 5.0% (P = .017). Additionally, 8.2% vs 3.9% of patients in each group, respectively, (P = .022) had empty packet dissection

Data from 844 patients were included in the trial, of whom 462 in group 1 had a BMI of less than 30 and 382 in group 2 had a BMI of 30 or more. Patients stratified 1:1 based on age, histotype, and lymphovascular space invasion. A total of 764 patients were identified based on this, and 382 patients were included in both groups 1 and 2-matched.

In the unmatched population, patients were 65 years or older in both group 1 and group 2, respectively (43.5% vs 50.8%; P = .035). Patients had similar surgical and histopathological characteristics across both groups. Compared with group 1, patients who were obese were primarily operated on using a robotic approach (16.9% vs 48.2%; P <.001) and were less likely to undergo lumbo-aortic lymphadenectomy (7.8% vs 3.7%; P = .011). In group 2 vs group 1, there were higher rates of endometrioid (83.1% vs 88.0%; P = .048) and well-differentiated tumors (70.8% vs 80.6%; P = .001, respectively).

In the propensity-matched groups, patients in groups 2 and 1, respectively, were homogenized for variables that could negatively affect sentinel lymph node detection, which included age of 65 years or older (50.8% vs 50.8%; P = 1.00), non-endometroid histotype (12.0% vs 12.0%; P = 1.00), and presence of lumbo-aortic lymphadenectomy (27.7% vs 29.3%; P = .631). Between the 2 groups, statistical significance remained for surgical approach using robotics (18.3% vs 47.6%; P <.001), and tumor grading of 1 to 2 (74.3% vs 80.6%; P = .038), respectively.

In the matched population, group 2 vs group 1 had a significant reduction in overall detection rate (87.4% vs 92.9%; P = .011) and successful mapping (68.1% vs 75.7%; P = .020), with a higher rate of mapping failure (31.9% vs 24.3% vs; P = .020), respectively. Between the 2 groups, a superimposable percentage of metastatic lymph nodes (17.3% vs 16.0%; P = .634) and positive sentinel lymph nodes was observed (15.5% vs 14.6%; P = .742).

Patients who were non-obese vs those who were obese had comparable rates of isolated tumor cells (4.0% vs 5.2%; P = .442), micro-metastases (7.9% vs 5.8%; P = .276), and macro-metastases (5.1% vs 5.2%; P = .954). In group 2, 27 instances in which sentinel lymph node detection did not result in the identification of lymph node tissue at the final histopathological examination otherwise known as empty packet dissection compared with 14 cases in group 1 (3.9% vs 8.2%; P = .022).

Reference

Vargiu V, Rosati A, Capozzi VA, et al. Impact of obesity on sentinel lymph node mapping in patients with apparent early-stage endometrial cancer: the ObeLyX study. Gynecol Oncol. 2022;165(2):215-222. doi:10.1016/j.ygyno.2022.03.003