Melanoma SLN Micrometastases May Not Justify Complete Dissection

Complete lymph node dissection may be unnecessary for cutaneous melanoma patients with sentinel lymph node micrometastases

medwireNews: Results from a phase III trial challenge the use of complete lymph node dissection in cutaneous melanoma patients with sentinel lymph node (SLN) micrometastases, especially for those with only single cells or metastases no bigger than 1 mm.

The DeCOG–SLT investigators found no significant difference in 3-year distant metastasis-free survival for 240 patients randomly assigned to undergo complete dissection and 233 patients who received only observation, at 74.9% versus 77.0%.

Three-year overall survival was also comparable in the dissection and observation treatment groups, at 81.2% versus 81.7%, report Ulrike Leiter, from Eberhard-Karls-University of Tübingen in Germany, and co-authors in The Lancet Oncology.

“The only rationale for complete lymph node dissection in sentinel lymph node biopsy positive patients would be if the finding of additional nodal metastases would result in changes in adjuvant systemic therapy”, they write.

“As there are no differences in adjuvant systemic therapy based on the number of positive lymph nodes, complete lymph node dissection appears to be dispensable.”

Multivariate analysis indicated that tumour load in SLN biopsy and primary tumour thickness significantly predicted distant metastasis-free survival and overall survival, but receipt of complete dissection and number of positive nodes in SLN biopsy were not significantly associated with outcome.

Nor was distant metastasis-free survival significantly different in the dissection and observation groups between patients with micrometastases larger than 1 mm and the remainder who had smaller micrometastatic disease.

But the researchers caution that as only a third of the trial patients had a higher micrometastases burden, the conclusion that complete dissection should not be performed may not apply to this patient subgroup.

Writing in an accompanying comment, Charlotte Ariyan, from Memorial Sloan Kettering Cancer Center in New York, USA, describes the lack of benefit of complete dissection as a “remarkable finding”.

While acknowledging that the study was underpowered because a low accrual rate led to a smaller number of patients than planned, she notes that with the “almost completely overlapping curves of distant metastasis-free survival, overall survival, and recurrence-free survival, further accrual would be unlikely to change outcome”.

Indeed, Charlotte Ariyan writes that, on the basis of the DeCOG–SLT results, the US National Comprehensive Cancer Network has now changed the recommendation that melanoma patients with a positive SLN biopsy should undergo complete dissection to one where physicians should discuss and offer complete dissection.

“The MSLT-II trial (NCT00297895), a larger, worldwide, prospective randomised trial of ultrasound surveillance versus immediate complete lymph node dissection after positive sentinel lymph node biopsy will provide further guidance”, she adds.

“In the meantime, we should seriously reconsider the belief that all patients need a complete lymph node dissection after a positive sentinel lymph node biopsy.”

References

Leiter U, Stadler R, Mauch C, et al. Complete lymph node dissection versus no dissection in patients with sentinel lymph node biopsy positive melanoma (DeCOG-SLT): a multicentre, randomised, phase 3 trial.Lancet Oncol 2016; Advance online publication 5 May. DOI: http://dx.doi.org/10.1016/S1470-2045(16)00141-8

Ariyan C. Complete lymph node dissection in melanoma. Lancet Oncol 2016; Advance online publication 5 May. DOI: http://dx.doi.org/10.1016/S1470-2045(16)30071-7

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