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Preoperative PET/CT staging yields high false-positive rate in node-positive melanoma
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Preoperative PET/CT staging for the detection of clinically occult metastatic melanoma among patients with sentinel lymph node-positive melanoma has a high false-positive rate and a minimal effect on management, according to retrospective study results.
The procedure may be better reserved for its role evaluating treatment response and recurrence, according to researchers.
Mapping sentinel lymph nodes (SLNs) is critical to the staging of cutaneous melanoma because if a sentinel lymph node biopsy (SLNB) reveals regional metastases, an individual will undergo completion lymph node dissection (CLND) with curative intent, according to study background.
The National Comprehensive Cancer Network recommends — with a category 2b recommendation based on low-level evidence — PET/CT staging prior to CLND for prognostic purposes. The discovery of occult synchronous metastases may preclude the lymph node dissection and present an opportunity for a metastasectomy.
Benjamin Y. Scheier, MD, fellow in the division of hematology and oncology in the department of internal medicine at University of Michigan, and colleagues conducted this retrospective study to assess the use of PET/CT in detecting occult metastases in SLN-positive melanoma.
The investigators analyzed data from 46 patients treated at University of Michigan between April 2013 and September 2014 who had PET/CT prior to CLND.
Thirty-three percent of patients had intense uptake distant from the primary tumor and local lymph node basin. Of those patients, 60% had abnormalities biopsied prior to lymph node dissection.
Thirty-three percent of those biopsies (3 of 9) had metastatic melanoma, leaving a 67% false-positive rate for PET/CT.
Overall, only 7% of the patients in the population had PET/CT findings that identified metastatic melanoma, precluding the lymph node dissection.
Researchers observed no association between T stage and N stage regarding whether patients underwent PET/CT imaging.
“These data also suggest that a significant majority of asymptomatic patients with newly discovered microscopic SLN-positive melanoma do not have synchronous metastases detectable by PET/CT,” Scheier and colleagues wrote. “Our review also identified the potential for treatment delays, increased exposure to risk from additional procedures and increased health care resource usage that patients incur following detection of asymptomatic abnormalities by preoperative PET/CT. We recommend that PET/CT staging be reevaluated as a category 2B recommendation by the NCCN and its use further evaluated prospectively in a clinical trial.” – by Anthony SanFilippo
Disclosure: The researchers report no relevant financial disclosures.
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