Population-level trends and outcomes of sentinel lymph node biopsy in vulvar cancer surgery in the United States.

OBJECTIVE

To examine population-level trends, characteristics, and outcomes related to nodal assessment for vulvar cancer surgery in the United States.

METHODS

This is a retrospective cohort study querying the National Cancer Institute's Surveillance, Epidemiology, and End Results Program. The study population was 5604 women with T1b or T2-smaller(≤4 cm) squamous cell carcinoma of the vulva who underwent primary vulvectomy from 2003 to 2018. The exposure allocation was based on nodal evaluation type: lymphadenectomy (LND; n = 3319, 59.2%), sentinel lymph node (SLN) biopsy (n = 751, 13.4%), or no surgical nodal evaluation (n = 1534, 27.4%). The main outcomes were (i) trends and characteristics related to SLN biopsy assessed by multinomial regression model, and (ii) vulvar cancer-specific survival assessed by competing risk analysis and inverse probability of treatment weighting propensity score. Sensitivity analysis included evaluation of external cohort with T1a disease (n = 1291).

RESULTS

The utilization of SLN biopsy increased from 5.7% to 23.3% in 2006-2018, while the proportion of LND decreased from 64.1% to 48.8% in 2010-2018, and these associations remained independent in multivariable analysis (adjusted-P < 0.05). In the propensity score weighted model, 5-year cumulative rate for vulvar cancer-specific mortality was 15.2% (interquartile range 12.1-18.9) for the SLN biopsy group and 16.9% (interquartile range 15.6-18.3) for the LND group (subdistribution-hazard ratio 0.90, 95% confidence interval 0.76-1.06, P = 0.217). The increasing SLN biopsy use was also observed in T1a disease from 1.3% to 7.3% during the study period (P < 0.001).

CONCLUSION

The landscape of surgical nodal evaluation is shifting from lymphadenectomy to SLN biopsy in vulvar cancer surgery in the United States. SLN biopsy-incorporated treatment approach was not associated with worse survival compared to LND.