Nick Mulcahy

March 16, 2015

HOLLYWOOD, Florida ― Sentinel lymph node (SLN) biopsy, the common staging procedure, is not recommended for patients with melanomas that are ≤0.75 mm thick, according to guidelines from National Comprehensive Cancer Network (NCCN).

It is a rare ― and "very strong" ― bit of advice in the NCCN guidelines, said Daniel Coit, MD, of the Memorial Sloan Kettering Cancer Center (MSKCC), in New York City.

"There aren't many places in any of the guidelines where we say, 'Not recommended,' " he told an audience here today at the National Comprehensive Cancer Network 20th Annual Conference.

Dr Coit, who is chair of the organization's melanoma panel, explained that for these thin melanomas, only the variable of thickness is considered a reliable indicator for risk. Other indicators, such as ulceration, high mitotic rate, and lymphovascular invasion, are all uncommon in such thin melanomas.

"Thickness ought to be our primary determinant for performing sentinel lymph node biopsy," he said.

SLN biopsy is neither inexpensive or inconsequential, Dr Coit emphasized.

If 120 patients with thin melanomas undergo SLN biopsy, then six patients (5%) will have positive nodes, he said.

As a result, all patients will be offered completion lymph node dissection (CLND) and be considered for adjuvant therapy and follow-up imaging and be closely followed.

However, only one patient of the six with a positive node will subsequently die (a death that cannot be prevented), and the other five will survive.

The cost of identifying that one unpreventable death, if you estimate the price of an SLN biopsy to be about $10,000 (which does not include the adjuvant therapy, ect) is $1.2 million.

The psychological cost is also "tremendous," suggested Dr Coit, because the SLN procedure confers an element of risk to patients, leaving all 120 wondering if and when the "sword of Damocles" will fall.

The NCCN recommendation is similar to the American Society of Clinical Oncology (ASCO) and the Society of Surgical Oncology (SOS) guideline to skip SLN biopsy in patients with melanoma less than <1 mm thick that has no adverse features.

However, the procedure is controversial.

The 5-year follow-up of the landmark Multicenter Selective Lymphadenectomy Trial (N Engl J Med. 2006;355:1307-1317) failed to show a survival advantage from SLN biopsy. However, it did confirm that SLN biopsy was highly accurate in identifying positive nodes in patients with melanomas 1.2 to 3.5 mm thick and that SLN biopsy followed by CLND was associated with prolonged disease-free survival.

In many clinics, a positive sentinel lymph node biopsy automatically results in the more invasive CLND, pointed out Dr Coit. This is also what the NCCN recommends.

But this surgical practice is based on scant evidence, said Dr Coit.

The best evidence to date in support of this surgery is from a retrospective study done at MSKCC, he said. The study found that about 15% of patients who were candidates for CLND ― but were observed instead ― had a subsequent nodal basin failure (Ann Surg Oncol. 2014; 21:3117).

But there is no evidence that CLND improves survival in melanoma.

There is a lot of evidence that it results in morbidities.

Thus, the decision to have a CLND is based on emotions, said Dr Coit.

"This is an affair of the heart," he said about the decision to perform the full dissection after a positive sentinel node biopsy.

Another surgical oncologist at the meeting agreed.

 
It is the most difficult discussion that I have with melanoma patients. Dr Tom Thompson
 

"It is the most difficult discussion that I have with melanoma patients," said Tom Thompson, MD, of UT Surgical Associates of East Tennessee, in Morristown, who is not on the NCCN panel.

There is little or no evidence that the procedure is beneficial. "I can't assure them of an improved outcome," he told Medscape Medical News.

In Dr Coit’s practice, about 80% of melanoma patients with a positive sentinel node will not undergo a CLND, which defies NCCN guidance.

"There has to be discussion with the patient about the procedure," he said.

The talk should review the risks for various complications, suggested Dr Coit. According to one retrospective study of melanoma patients (Ann Surg. 2008;247:687), there is significant morbidity in neck (8%), axilla (47%), and groin (48%) after CLND. Also, reoperation took place commonly in the axilla (9%) and groin (26%).

Overall, it's time to dial back surgery on the lymph nodes in melanoma patients with localized disease, suggested Dr Coit.

However, the NCCN panel is "conservative," he said, and thus uniformly recommends CLND when a sentinel node is positive.

"Fundamentally, this is an emotional decision," he told the audience.

Dr Coit has disclosed no significant financial relationships.

National Comprehensive Cancer Network (NCCN) 20th Annual Conference. Presented March 12, 2015.

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