C. T. Mayemura1, S. O’Brien1, E. A. O’Halloran1, G. Gauvin1, E. E. McGillivray1, K. Liang1, K. Loo1, A. J. Olszanski2, S. Movva2, B. Luo5, H. Wu4, J. Q. Yu3, S. Reddy1, J. M. Farma1 1Fox Chase Cancer Center,Department Of Surgical Oncology,Philadelphia, PA, USA 2Fox Chase Cancer Center,Department Of Hematology/Oncology,Philadelphia, PA, USA 3Fox Chase Cancer Center,Department Of Diagnostic Imaging,Philadelphia, PA, USA 4Fox Chase Cancer Center,Department Of Pathology,Philadelphia, PA, USA 5Fox Chase Cancer Center,Molecular Diagnostics Laboratory,Philadelphia, PA, USA
Introduction: While current guidelines do not recommend the use of PET/CT scans in the initial evaluation of stage 1 and 2 melanoma, recent studies have shown that in certain subsets of cases, preoperative PET/CT may be beneficial. We report our experience with high-risk stage II melanoma patients who underwent PET/CT prior to surgery and their clinical outcomes.
Methods: Using our prospectively maintained melanoma database at our tertiary referral center, we identified and selected clinically staged II patients who underwent preoperative PET/CT between 2004 and 2018. We specifically evaluated any change in their treatment course, defined as any additional biopsy, imaging, consult, or change in surgical planning. We calculated the average time from diagnosis (initial biopsy date) to surgery, between those who underwent PET and those who did not to look for any associated delay, compared by unpaired t-test.
Results: Of 290 stage II melanoma patients, 106 patient received preoperative PET scans. Of these, 63% were male, and were stage IIA (N=30), stage IIB (N=43), and stage IIC (N=33). The median age was 71.5 years, median tumor thickness was 3.5 mm, median mitotic rate was 6 (per mm2), and 62 were ulcerated. Twenty-three patients (22%) had a change in treatment. In 12 patients, the PET was concerning for metastatic melanoma: 7 underwent additional biopsies (1 positive for metastatic melanoma to the femur, 2 for lymphoma, 1 for recurrent Merkel Cell carcinoma, and 3 false positives), 1 had an additional lymph node basin dissection, and 4 underwent lymph node dissection instead of sentinel lymph node biopsy after positive biopsy for metastatic melanoma of PET positive lymph node. In total, of these 12, 5 were confirmed to have advanced melanoma, and 3 went on to systemic therapy. Eleven cases had incidental findings: 3 had additional consults (2 urology, 1 gastroenterology), 3 underwent colonoscopy, 2 had additional imaging (1 led to diagnosis of squamous cell carcinoma of the lungs), and 3 had thyroid evaluation (1 positive for papillary thyroid carcinoma). The average time from diagnosis to surgery for the patients who underwent PET was 48.89 days, and 34.30 days for those without PET (p=0.019).
Conclusion: Approximately one in five patients (22%) with high risk stage 2 melanoma who had a preoperative PET scan had their treatment course changed, although this was associated with a clinically non-significant 14-day delay from diagnosis to surgery. However, fourteen of the positive PET findings ended up being unrelated to melanoma and 26% (N=6) changed melanoma specific management. A second cancer was discovered in 5 patients. These findings are important and further larger studies in this specific group are warranted.