PET-CT underestimates the true pathological extent of disease at lymphadenectomy for melanoma patients after systemic therapy

Eyal Mor, Gal Schtrechman, Eran Nizri, Michal Shimonovitz, Nethanel Asher, Guy Ben-Betzalel, Shirly Grynberg, Ronen Stoff, Mor Miodovnik, Mohammad Adileh, Almog Ben-Yaacov, Yael Steinberg, Ronnie Shapira, Jacob Schachter, Guy Lahat, Aviram Nissan, Douglas Zippel, Shachar Laks*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Introduction: Modern systemic therapy has revolutionized the treatment of melanoma. Currently, patients with clinically involved lymph nodes require lymphadenectomy with associated morbidities. Positron Emission Tomography – Computed Tomography (PET-CT) has demonstrated accuracy in melanoma detection and response to therapy. We aimed to identify whether a PET-CT directed lymphatic resection after systemic therapy is oncologically sound. Materials and methods: Retrospective review of patients who underwent lymphadenectomy after systemic therapy for melanoma with a preoperative PET-CT. Examined demographic, clinical, and perioperative parameters including extent of disease, systemic therapy and response, and PET-CT findings compared to pathological outcomes. We compared patients with “as or less than expected” outcomes on pathology against those with “more than expected” pathological outcomes. Results: Thirty-nine patients met inclusion criteria. In 28 (71.8%), pathological outcomes were “as or less than expected” by PET-CT, and in 11 (28.2%) pathological outcome were “more than expected”. “More than expected” occurred more frequently with advanced disease at presentation with 75% presenting with regional/metastatic disease versus only 42.9% in the “as or less than expected” group (p = 0.015). Poor response to therapy also trended towards the “more than expected” group with only 27.3% favorable response versus 53.6% favorable response in the “as or less than expected” group, not statistically significant. Extent of disease on imaging failed to predict pathological concordance. Conclusion: PET-CT underestimates pathological extent of disease in the lymphatic basin in 30% of patients after systemic therapy. We failed to identify predictors of more extensive disease and warn against limited PET-CT directed lymphatic resections.

Original languageEnglish
Article number106950
JournalEuropean Journal of Surgical Oncology
Issue number10
StatePublished - Oct 2023
Externally publishedYes


  • Immunotherapy
  • Lymphadenectomy
  • Melanoma
  • PET-CT
  • Targeted therapy


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