Preoperative 3D visualisation of sentinel lymph nodes (SLNs) via SPECT/CT was associated with a higher rate of detection of positive SLNs and a higher rate of disease-free survival among patients with melanoma, according to a study in the September 12 issue of Journal of the American Medical Association.
The incidence of melanoma is rising faster than other cancers, with more than 70,000 new cases diagnosed in the US in 2011. The disease, which accounts for less than 5% of skin cancers, is responsible for more than 75% of skin cancer deaths.
“Because melanoma, depending on tumour depth, metastasises early into regional lymph nodes, sentinel lymph node excision (SLNE) is probably the most important diagnostic and potentially therapeutic procedure for patients with melanoma. The histological status of the sentinel lymph node is the most relevant prognostic factor for overall survival in patients with melanoma, independent of primary tumour thickness,” wrote Ingo Stoffels, MD, from the departments of dermatology, venereology and allergology at the University of Essen-Duisberg in Essen, Germany, and colleagues.
However, the utility of SLNE is comprised by a false-negative rate that may reach 44%.
Stoffel and colleagues hypothesised that preoperative SLN mapping via SPECT/CT could provide additional information to the surgeon. The researchers sought to compare the association between SLNE with versus without SPECT/CT and metastatic node detection and disease-free survival in melanoma patients.
They identified 464 patients eligible for SLNE between March 2003 and April 2011. A total of 403 patients with clinically negative lymph nodes, who underwent SLNE with or without preoperative SPECT/CT, qualified for subsequent analysis. Between March 2003 and October 2008, 254 patients with melanoma underwent SLNE without preoperative SPECT/CT. Between November 2008 and April 2011, all sentinel node scintigraphies were performed as SPECT/CT in 149 patients.
A total of 833 SLNs were removed from 403 patients. The researchers found 2.4 SLNs per patient in the SPECT/CT group and 1.87 SLNs per patient in the standard group; 14.2% of excised SLNs in the SPECT/CT cohort and 11.4% of SLNs in the standard cohort showed metastatic involvement.
Stoffel and colleagues identified 27.5% of patients with positive SLNs in the SPECT/CT cohort and 18.9% with positive SLNs in the standard cohort. The number of positive SLNs per patient was significantly higher in the SPECT/CT cohort than in the standard cohort (0.34 vs. 0.21).
“The local relapse rate in the SPECT/CT cohort was lower than in the standard cohort (6.8% vs. 23.8%), which prolonged four-year disease-free survival (93.9% vs. 79.2%),” the researchers wrote. They also found lower morbidity in the SPECT/CT cohort than in the standard group (4% vs. 7.9%). In addition, the authors noted that with the SPECT/CT technique, they were able to use smaller incisions in the head and neck area as well as alternative entry points due to the exact anatomical localisation of the SLN.
Other researchers have identified additional benefits of SPECT/CT in this population. These include sparing patients the risks and effects of general anaesthesia and minimising the risks of aspiration pneumonitis and adverse effects of tracheal intubation.
“In conclusion, the preoperative visualisation of SLN with SPECT/CT is technically feasible and facilitates the detection of additional positive SLNs. The use of this technique offers the physician the preoperative possibility of determining the exact location and visualisation of the SLN,” wrote Stoffel et al.