Cost-effectiveness of sentinel lymph node biopsy vs inguinofemoral lymphadenectomy in women with vulval cancer

Abstract

Background: This study examines the cost-effectiveness of sentinel lymph node biopsy, a potentially less morbid procedure, compared with inguinofemoral lymphadenectomy (IFL) among women with stage I and stage II vulval squamous cell carcinoma.

Methods: A model-based economic evaluation was undertaken based on clinical evidence from a systematic review of published sources. A decision tree model was developed with the structure being informed by clinical input, taking the perspective of the health-care provider.

Results: For overall survival for 2 years, IFL was found to be the most cost-effective option and dominated all other strategies, being the least costly and most effective. For morbidity-free related outcomes for 2 years, sentinel lymph node (SLN) biopsy with 99mTc and blue dye and haematoxylin & eosin (H&E) histopathology, with ultrastaging and immunohistochemistry reserved for those that test negative following H&E is likely to be the most effective approach.

Conclusion: SLN biopsy using 99mTc and blue dye with ultrastaging may be considered the most cost-effective strategy based on the outcome of survival free of morbidity for 2 years. The findings here also indicate that using blue dye and H&E for the identification of the SLN and the identification of metastasis, respectively, are not sensitive enough to be used on their own.

Figure 1

Summary of the decision pathway used in the economic model.

Figure 2

Model structure showing each of the seven primary treatment pathways, and the subsequent treatment pathway for blue dye+H&E. This is repeated for each of the pathways that include either blue dye and/or 99mTc.

Figure 3

Cost-effectiveness acceptability frontier showing the results of the probabilistic sensitivity analysis examining the optimal treatment strategy across a range of willingness to pay thresholds for the outcome of additional case of survival free of morbidity for 2 years.

Figure A1

Treatment pathway following an IFL.

Figure A2

Treatment pathway for strategies 2–6 following a true-positive result for metastasis.

Figure A3

Treatment pathway for strategies 2–6 following a false-negative result for metastasis.

Figure A4

Treatment pathway for strategies 2–6 following a true-negative result for metastasis.

Figure A5

Scatterplot showing the uncertainty in costs and effectiveness within the model for each of the seven strategies for 1000 runs with overall survival for 2 years as the outcome measure

Figure A6

Scatterplot showing the uncertainty in costs and effectiveness for each of the seven strategies for 1000 runs with survival free of morbidity as the outcome measure

Figure A7

Scatterplot showing the uncertainty in costs and effectiveness within the model for each of the 7 strategies for 1000 runs with survival free of long-term morbidity for 2 years as the outcome measure

Figure A8

Cost-effectiveness acceptability frontier showing the results of the sensitivity analysis examining the optimal investigative strategy across a range of willingness to pay thresholds for the outcome of additional case of survival free of long-term morbidity