A phase 3 trial of patients with cutaneous melanoma found no difference in distant metastasis-free survival between those who underwent complete lymph node dissection and those who did not.1 The authors concluded that complete dissection should no longer be recommended for patients with micrometastases smaller than 1 mm in diameter.

“In patients with positive sentinel node biopsy, complete lymph node dissection was recommended as mandatory,” said study coauthor Claus Garbe, MD, of the University Hospital Tuebingen in Germany, in an interview with Cancer Therapy Advisor. “We were able to show that complete lymph node dissection in patients with positive sentinel node biopsy is not associated with any survival benefit.”

“We recommend that complete lymph node dissection should not be performed on patients for whom the largest tumor diameter measures up to 1 millimeter, and should be critically discussed in patients with larger tumor diameters,” said Dr Garbe. “This would avoid the significant morbidity associated with complete lymph node dissection.”

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Between January 2006 and December 2014, 483 patients were enrolled and randomly assigned either to undergo complete lymph node dissection (242 patients) or to an observation-only group (241 patients). Sentinel lymph node metastases smaller than 1 mm were found in 311 patients. After 3 years, distant metastasis-free survival was 74.9% in the lymph node dissection arm and 77% in the observation arm. Three-year overall survival was 81.2% in the dissection arm and 81.7% in the observation arm. The authors are planning a second study with a 6-year follow-up.

Because of failure to meet planned patient accrual, the study’s statistical power was reduced from 80% to 50%. The authors contended, however, that their findings support a recommendation against complete lymph node dissection, citing a number of similar studies that were also underpowered.

“I have no concerns about validity,” said Dr Garbe. “This study was designed to show superiority of complete lymph node dissection over observation with a 70% 3-year distant metastasis-free survival versus 60% for the observation arm. In our study the difference was 0, not only in distant metastasis-free survival, but in progression-free survival and overall survival.”

Charlotte Ariyan, MD, of Memorial Sloan Kettering Cancer Center in New York, New York, defended the study’s conclusions, arguing that “further accrual would be unlikely to change outcome.”2

Dr Ariyan observed that additional disease is detected in just 20% of patients who undergo a complete lymph node dissection following a positive sentinel lymph node biopsy, and wrote that “5-year survival for stage IIIa and IIIb melanoma is 78% and 59%, respectively,” which suggests that dissection “might not mitigate the risk of distant disease.”