Sentinel node biopsy claims earn sharp rebuke

Skin cancers

By Heather Wiseman

25 Oct 2018

Claims by a Sydney dermatologist that sentinel lymph node biopsy does not deserve its status as the most powerful predictor of prognosis in cutaneous melanoma have been met with sharp rebuke.

In an opinion piece in the Australasian Journal of Dermatology Dr Samuel Zagarella, a senior dermatologist at Concord Hospital, Sydney, said sentinel node biopsy (SNLB) had achieved its status as the most valuable prognostic marker for melanoma, ahead of more established markers such as Breslow thickness, because evidence had been misinterpreted.

“A careful examination of the evidence for these claims indicates that they are not substantiated by the available data, are somewhat misleading and suggest misinterpretation of the statistical analysis of the papers to which they refer,” they wrote.

Along with his pathology colleagues Dr Stephen Lee and Dr Peter Heenan, Zagarella said it was “somewhat simplistic” to proclaim one factor (SNLB) as the most powerful predictor’ when this cannot be substantiated.

“There is no convincing evidence that SLN status is a strong predictor of survival status when compared to a combination of Breslow thickness, ulceration, mitotic rate, age and other factors,” they wrote.

Instead, they said the prognostic power of sentinel lymph node status would be best assessed by a direct comparison with Breslow thickness (alone or in combination) with other clinico-pathologic factors.

However, the opinion piece was met with derision by an international group led by Dr Erica Friedman from the Melanoma Institute Australia.

In a letter to the editor they claimed Zagarella and colleagues offered no new primary data to support their view and had misinterpreted the available data.

“The overwhelming body of evidence that SN status provides important staging information in addition to that provided by patient factors and primary tumour thickness was overlooked, and the recommendations of the American Society of Clinical Oncology and the Society of Surgical Oncology were ignored,” they wrote.

Criticising the staging procedure on the basis that some patients with a negative biopsy would eventually die of their disease was “illogical”.

They added that Breslow thickness was a “similarly imperfect” measure of risk, given other independent predictors of survival including the site of the original primary and age and sex of the patient.

“No one pathological pathologic feature is examined in isolation” when staging a patient, and debating whether sentinel node’s status was the most important prognostic factor was “unhelpful” they said.

“It is but one of several prognostic factors, albeit the most important one in most large studies to date,” she wrote, adding that it provides highly valuable information for recommending treatment and planning follow-up.

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