Single-photon emission computed tomography/computed tomography imaging before sentinel lymph node excision was associated with significantly higher disease-free survival rates in melanoma patients, according to the results of a new study published in JAMA Sept. 12.
In addition to less local relapse and a better 4-year progression-free survival, SPECT/CT was associated with the detection of more positive nodes, more sentinel lymph node-excision (SLNE) procedures performed in the head and neck area, and improved detection of positive nodes in obese patients than standard SLNE (JAMA 2012;308:1007-14).
Copyright the National Cancer Institute
Patients with melanoma (pictured) enjoyed much better survival rates with SPECT/CT imaging before SLN excision.
SPECT/CT offers "the preoperative possibility of determining the exact location and visualization of the SLN, especially if the tracer signal is too weak for detection by the handheld gamma probe alone or the SLN is in the immediate vicinity of the remaining tracer depot," Dr. Ingo Stoffels and colleagues wrote. They noted that for 33 patients in the SPECT/CT cohort, the surgical approach was changed based on SPECT/CT findings.
Dr. Stoffels, of the University of Essen-Duisburg, Germany, and colleagues, analyzed a cohort of 403 patients with clinically negative lymph nodes. All patients underwent SLNE with (149) or without (254) preoperative SPECT/CT between 2003 and 2011 at a skin cancer treatment facility where, after 2008, preoperative SPECT/CT became the standard of care.
Dr. Stoffels and colleagues found that SPECT/CT allowed SLNEs in the head and neck more frequently (23.5% for SPECT/CT, compared with 2% for standard care). Also, more SLNs per patient were detected in the SPECT/CT cohort than in the SLNE alone cohort (2.40 vs. 1.87, respectively), and the number of positive SLNs per patient was also higher in the SPECT/CT cohort (0.34 vs. 0.21). The false-negative SLN rate was 6.8% in the SPECT/CT cohort and 23.8% in the SLNE alone cohort.
Importantly, the local relapse rate in the SPECT/CT cohort was lower than in the SLNE alone cohort (6.8% vs. 23.8%, respectively), and 4-year disease-free survival was higher in the SPECT/CT cohort than in the SLNE alone cohort (93.9% vs. 79.2%, respectively). However, overall survival did not differ between the cohorts.
Dr. Stoffels and colleagues also found that SPECT/CT improved detection of positive SLNs among patients with a body mass index of 30 or higher; 5 positive SLNs out of 20 were detected (25%) in 7 obese patients in the SPECT/CT cohort, compared with 4 positive SLNs out of 44 (9.1%) in 24 obese patients in the SLNE alone cohort.
"Our results demonstrate clear advantages of adding the described preoperative SLN imaging by SPECT/CT to the current practice of preoperative lymphoscintigraphy in patients with melanoma," the investigators wrote.
They acknowledged that the temporal separation of the two cohorts was a limitation of the study as it "could lead to a bias for the time-dependent end points."
The investigators received no outside funding for their research. A coauthor, Dr. Dirk Schadendorf, disclosed receiving consultancy fees, board membership, and lecture fees from Amgen, Bristol-Myers Squibb, Genentech, GlaxoSmithKline, MSD, Novartis, and Roche.