Clinical Value of SPECT/CT for Sentinel Lymph Node Identification in Melanoma
Amanda Norwich, MD, Andrew McGregor, MD, Samuel Kim, MD, Sun Haosi, BS, Deena Abate, RN, Antonio Obando, MD, Deepak Narayan, MD.
Yale University Division of Plastic and Reconstructive Surgery, NEW HAVEN, CT, USA.
Melanoma is the deadliest form of skin cancer with the ability to metastasize throughout the body. Accurate diagnosis of sentinel lymph nodes (SLN) is crucial in its management. The gold standard for SLN identification has been planar lymphoscintigraphy. Recently, single-photon emission computed tomography combined with computed tomography (SPECT/CT) has been used as a hybrid method of mapping of lymphatic drainage networks. We have set out to better characterize the utility of this tool in head and neck melanoma. Our aim is to evaluate its effectiveness in the preoperative setting for melanoma patients undergoing sentinel lymph node biopsy (SLNB) followed by a brief discussion about cost-effectiveness.
We performed a retrospective chart review at the West Haven Veterans Affairs Hospital. Inclusion criteria for our review were patients with melanoma with a thickness greater than 0.75mm and SPECT/CT use prior to operative sentinel lymph node excision. Exclusion criteria included clinically palpable lymph nodes, evidence of distant metastatic disease, melanoma with a Breslow depth less than 0.75mm, and melanoma in situ. Our primary endpoints were correlation with intraoperative findings and whether the test had any influence on the operative plan.
Thirty-five patients between 2011 and 2017 met our criteria. SPECT/CT correlated with the sentinel node biopsy based on intraoperative lymphoscintigraphy in 30 of 35 cases (86%) and there were no changes to the operative plan after SPECT/CT was performed. All 35 cases of operative sentinel lymph node biopsy correctly identified the sentinel lymph nodes.
The role of SPECT/CT in SLNB is uncertain. According to some studies, SPECT/CT can help decision making and change the surgical approach in up to 35% of patients. However, other studies have reported that preoperative lymphoscintigraphy has been inconsistent with intraoperative findings up to 42% of the time. We have demonstrated that preoperative SPECT/CT was consistent with intraoperative findings in 86% of cases but did not change the surgical approach for the sentinel lymph node biopsy. Surveillance over a period of 12 months did not reveal any signs of melanoma recurrence. A possible advantage of SPECT/CT is potentially decreasing costs by lowering operative time. However, at most institutions, the test requires an additional preoperative visit by the patient, which may pose an additional burden. Financial cost in the literature allow inference SPECT/CT is costlier than lymphoscintigraphy and therefore this must be weighed against any potential benefit.
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