The Role Of Sentinel Lymphadenectomy In Thin Cutaneous Melanomas

Reviewer: Heather Jones, MD
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: May 18, 2002

Presenter: Richard J. Bleicher
Presenter's Affiliation: The John Wayne Cancer Institute, Santa Monica, CA
Type of Session: Scientific

Background

The sentinel lymph node (SLN) biopsy is revolutionizing the surgical management of primary malignant melanoma. Lymphatic mapping and sentinel lymphadenectomy (LM/SL) has become standard to assess regional lymph nodes because LM/SL is highly accurate and minimally morbid. It allows accurate nodal staging, and targets patients who may benefit from regional lymphadenectomy and systemic therapy; however, its use in the management of thin (< 1.5 mm thick) primary melanoma has not been fully determined. This study evaluates the role of SLN biopsy in this clinically setting.

Materials and Methods

This study was a single institution review of a computerized database from 1985-2000
512 patients were eligible who underwent LM/SL for cutaneous melanomas < 1.5 mm thick
Following preoperative lymphoscintigraphy, LM/SL was performed using blue dye alone or with radiopharmaceutical
Patients with tumor-positive sentinel lymph nodes (SNs) underwent complete dissection

Results

57% of the patients were male abd the median age was 49 years (range, 15-90 years)
a majority of primaries were on the torso (44%)
Twenty-five patients (4.9%) had tumor-positive SNs (mean, 1.24 positive SN/patient)
The thinnest SN+ lesion was 0.35 mm.
The SN- and SN+ cohorts were statistically equivalent by sex, but patients with positive nodes tended to be younger (p = 0.053)
For the 272 patients with lesions <1.00 mm, 2.9% were SN+, and 1.7% of patients with lesions <0.75 mm had nodal metastases.
The rate of SN positivity was 7.1% for lesions between 1.01 and 1.50 mm
All 13 deaths in this study were SN- patients.
Median follow-up in SN+ and SN- patients was 25 and 45 months, respectively

Author's Conclusions

In patients with primary melanomas (1.00-1.50 mm) the high rate of nodal positivity suggests that LM/SL is indicated in all lesions >1.00 mm.
Young age may correlate with nodal metastases in patients with lesions <1.00 mm.
Lesions <0.75 mm have minimal metastatic potential and therefore LM/SL is rarely indicated except in younger patients.

Clinical/Scientific Implications

SLN biopsy is a feasible technique with an acceptable failure rate and is thus a useful tool in the surgical management of melanoma. We know that ulceration and location are important predictors of metastatic potential. This study would also indicate that age might also be an important predictive variable in thin melanomas. The higher rate of death in the SN- group is most likely related to the much longer follow-up time.

Oncolink's ASCO Coverage made possible by an unrestricted Educational Grant from Bristol-Myers Squibb Oncology.