Assessment of sentinel Lymph node mapping with different volumes of Indocyanine green in early-stage ENdometrial cancer: the ALIEN study

Objective To evaluate the impact of different volumes of indocyanine green (ICG) on the detection rate and bilateral mapping of sentinel lymph nodes in patients with apparent uterine-confined endometrial cancer. Methods All patients who underwent surgical staging with sentinel node mapping in six reference centers were included. Two different protocols of ICG intracervical injection were used: (1) 2 mL group: total volume of 2 mL injected superficially; (2) 4 mL group: total volume of 4 mL, 2 mL deeply and 2 mL superficially. Logistic regression was used to analyze factors that could influence dye migration and detection rates. A sensitivity analysis was carried out to determine how independent variables could affect the sentinel node detection rate. Results Of 442 eligible patients, 352 were analyzed (172 in the 2 mL group and 180 in the 4 mL group). The bilateral detection rates of the 2 mL and 4 mL groups were 84.9% and 86.1%, respectively (p=0.76). The overall detection rate was higher with a volume of 4 mL than with 2 mL (92.4% vs 97.8%, respectively; p=0.024). In the univariate analysis the rate of bilateral mapping fell from 87.5% to 73.5% when the International Federation of Gynecology and Obstetrics (FIGO) 2009 tumor stage was >IB (p=0.018). In the multivariate analysis, for both overall and bilateral detection rates a statistically significant difference emerged for the volume of ICG injected and FIGO 2009 stage >IB. Increasing body mass index was associated with worse overall detection rates on univariate analysis (p=0.0006), and significantly decreased from 97% to 91% when the body mass index exceeded 30 kg/m2 (p=0.05). Conclusions In patients with early-stage endometrial cancer, a volume of 2 mL ICG does not seem to compromise the bilateral detection of sentinel lymph nodes. In women with obesity and FIGO 2009 stage >IB, a 4 mL injection should be preferred.