When to perform sentinel lymph node biopsy depends on various factors

Guidelines from organizations including the American Academy of Dermatology, the American Joint Cancer Commission (AJCC) and the National Comprehensive Cancer Network (NCCN) tend to agree on when and when not to recommend SLNB, says Dr. Curiel-Lewandrowski, associate professor of dermatology, University of Arizona Cancer Center. Of these, she says the NCCN guidelines are perhaps most comprehensive.

Overall, “NCCN guidelines are not a mandatory recommendation on SLNB indications. They state the need to discuss and potentially offer this procedure to those patients who could be eligible for it,” she says.

Eligible patients include those in stage 1b (less than or equal to 1 mm thick, with ulceration or mitotic rate/MR greater than or equal to 1/mm², or 1.01 mm to 2 mm thick without ulceration) or stage 2 (1.01 mm to 2 mm thick with ulceration, or greater than 2 mm thick). AJCC staging guidelines added MR for thin melanoma (less than or equal to 1 mm) in 2010, she notes.

For stage 1a (less than 1 mm thick, without ulceration and mitotic rate less than 1/mm²), “There are no uniformly accepted guidelines, although SLNB is generally not recommended when no adverse histologic features are present,” Dr. Curiel-Lewandrowski says. “A particular circumstance is when tumors less than 1 mm thick broadly extend to the base of the specimen. In these situations, we don’t have an accurate depth representation.” These patients might be candidates for SLNB, she says, as could those with thin tumors with lymphovascular invasion, although this is an uncommon event.

More specifically, NCCN guidelines suggest that physicians consider SLNB for patients with stage 1a melanoma when adverse features that might suggest a higher risk of sentinel-node involvement are observed, such as tumor thickness of 0.75 mm or more, positive deep margins, lymphovascular invasion or Clark level 4 or 5 (http://www.nccn.org/professionals/physician_gls/pdf/melanoma.pdf).

“Another area of controversy regarding the implementation of SLNB includes melanomas between 0.75 and 1 mm in depth,” Dr. Curiel-Lewandrowski says. “Some reports indicate that there’s a relevant rate of SLNB positivity in this group of patients.”

For tumors 0.5 mm thick or less with fewer than two mitoses per mm², “The overall consensus is that SLNB should not be recommended in this group of patients unless other adverse clinical factors are present. Implementing these guidelines is not a cookie-cutter process. Each patient is different, and we must consider these and other variables when we assess the patient.”

Providing prognoses

Assessing tumor characteristics begins with the AJCC staging process, Dr. Curiel-Lewandrowski says. This process highlights the relevance of the SLNB procedure, designed to properly stage melanoma patients and provide more accurate prognostic information.

More specifically, she says that patients with stage 1b tumors at presentation and negative SLNB have a five-year survival rate of approximately
92 percent, versus 78 percent for patients presenting with similar primary tumors and demonstrating positive micrometastatic involvement in two lymph nodes.

“Some of your patients want to know this information. Our responsibility is to inform them about their options and make decisions together with them, not for them,” she says.

One Web-based predictive tool that patients find helpful is available at www.melanomaprognosis.org. Here, physicians or patients can punch in factors such as patient age, tumor depth and other characteristics and receive one-, two-, five- and 10-year survival rates (Balch CM, Gershenwald JE, Soong SJ, et al. J Clin Oncol. 2009;27(36):6199-6206. Epub 2009 Nov 16).

“When you have the patient in front of you and you plot their survival information, it facilitates in many instances the patient’s understanding of how we arrived at a specific prognostic figure,” Dr. Curiel-Lewandrowski says, adding that this sets the groundwork for discussing the patient’s melanoma treatment.

When discussing the management of a primary melanoma with the patient, “The first step will be to clarify the wide local excision surgical margins,” she says. Recommended surgical margins vary from
0.5 cm to 2 cm, depending on melanoma thickness. “Margins have been well established, and most organizations have adopted these criteria.”

Survival and SLNB

Depending on the patient’s primary tumor characteristics, associated comorbidities, age, and individual preferences, a discussion on the prognostic value of SLNB will follow. Dr. Curiel-Lewandrowski also recommends discussing with patients the likelihood that they’ll have positive nodes.

A published analysis shows that a 1.1 mm ulcerated melanoma has a 22 percent chance of demonstrating a positive lymph node (Rousseau DL Jr, Ross MI, Johnson MM, et al. Ann Surg Oncol. 2003;10(5):569-574). “Providing the rate of predicted nodal positivity is important to several patients when making the decision on whether or not to undergo SLNB,” she says.

The goal of SLNB is to accurately stage patients with respect to their lymph node status, Dr. Curiel-Lewandrowski says. For this, “It is an effective tool. The rate of same lymph node basin nodal recurrence after SLNB in some studies is less than 5 percent (Valsecchi ME, Silbermins D, de Rosa N, et al. J Clin Oncol. 2011;29(11):1479-1487). Therefore, only a small percentage of SLNB procedures fail to identify the metastatic node.”

SLNB also can enhance regional disease control. In this regard, “It’s much easier to manage metastatic disease at the nodal basin, when it’s microscopic, than when a patient presents with macroscopic disease, which results in increased morbidity,” she says.

Whether SLNB improves survival remains controversial. “We’re waiting on the results of the Multicenter Selective Lymphadenectomy Trial (MSLT-II) 10-year follow-up to determine if there are any additional considerations when discussing the survival advantage of this procedure with patients,” Dr. Curiel-Lewandrowski says. DT

Disclosures: Dr. Curiel-Lewandrowski is a consultant for MELA Sciences and Medical Directions, and an investigator for SciBase, a stockholder for DermSpectra.