Feasibility of intraoperative injection of radioactive tracer and blue dye for sentinel lymph node biopsy in vulvar cancer.

Objective: The objective of this study was to examine the feasibility and success rate of intraoperative injection of radiotracer and blue dye performed by the surgeon without the use of preoperative lymphoscintigraphy for the detection of sentinel lymph nodes in clinically early stage vulvar cancer.

Methods: All patients with clinically early stage vulvar cancer who underwent attempted sentinel lymph node biopsy using intraoperative injection of Technetium-99 m (99mTc) tracer and blue dye performed by the surgeon after induction of anesthesia at single academic institution from 12/2009 to 5/2022 were identified. Demographic and clinicopathologic variables were collected. Data were compared using descriptive statistics.

Results: One hundred sixty-four patients (median age 66.4 years) underwent intraoperative injection of radioactive tracer and dye for sentinel lymph node biopsy. Most patients (n = 156, 95.1%) were white. Squamous cell carcinoma accounted for 138 cases (84.1%), melanoma for 10 (6.1%), extra-mammary invasive Paget's disease for 11 (6.7%), and other histologies for 5 (3%). A majority of cases were stage I disease on final pathology (n = 119, 72.6%). Most patients (n = 117, 71%) had tumors located within 2 cm of the midline and underwent planned bilateral groin assessment, while 47 (29%) had well lateralized lesions and underwent unilateral groin assessment. For the patients undergoing unilateral groin assessment, 44 of 47 (93.6%) had successful unilateral mapping. Of the patients who underwent bilateral groin assessment, 87 of 117 (74.4%) had successful bilateral mapping, and 26 of 117 (22.2%) had successful unilateral mapping. Of the 26 patients who underwent bilateral assessment but only had unilateral mapping, 19 had unilateral mapping to ipsilateral groin but failed contralateral mapping, six had midline lesions with successful mapping to one groin but failed mapping to the other groin, and one had unilateral mapping to the contralateral groin but not ipsilateral groin. The total successful sentinel lymph node mapping rate in this cohort was 86.5% (243/281 total sentinel lymph node attempts).

Conclusion: In this cohort, the overall success rate of sentinel lymph node mapping and biopsy was 86.5%. The high rate of successful sentinel lymph node mapping supports the use of intraoperative radiotracer and blue dye injection by trained providers.