Debating melanoma options: Controversy continues over value of sentinel lymph node biopsy versus complete dissection

Chicago - In melanoma patients, debate continues over the value of sentinel lymph node biopsy (SLNB) and complete lymph node dissection (CLND), as well as interest in validating the benefit of interferon-alpha2b. Two major studies presented at the American Society of Clinical Oncology add fuel to these fires.

The MSLT-1 trial previously showed that sentinel node positivity is an important predictor of outcome in patients with primary melanomas, and that SLNB was associated with improved relapse-free survival - though not overall survival - compared to observation.

The results were considered underpowered, and investigators from the University of Pennsylvania performed an analysis of similar patients in the Surveillance Epidemiology and End Results (SEER) database to see how it compared.

The SEER analysis (1998-2002) matched melanoma patients who underwent SLNB with comparable patients who did not. This resulted in 674 matched pairs with intermediate melanomas (1.2 mm to 3.5 mm) and 1,126 pairs with thin melanomas (0.75 mm to 1.19 mm).

Phyllis Gimotty, Ph.D., professor of biostatistics, University of Pennsylvania, Philadelphia, says that five-year survival was significantly better for patients with intermediate melanomas undergoing SLNB: 91.9 percent versus 82.6 percent without (P < .0001), for a 9.3 percent difference between the arms.

In the MSLT-1 trial, a trend favored SLNB, the difference being approximately 7 percent (P = .056).

"Our findings are consistent with biopsy having a therapeutic effect on intermediate thickness and thin melanomas, though it is of less magnitude in thinner melanomas," Dr. Gimotty tells Dermatology Times.

Sunbelt Melanoma Trial

In the long-running Sunbelt Melanoma Trial, however, SLNB did not influence survival in the population of patients with melanoma cells detected in the sentinel nodes, says Kelly M. McMasters, M.D., Ph.D., of the University of Texas M.D. Anderson Cancer Center, Houston.

The study also failed to show a benefit for adjuvant high-dose interferon-alpha2b for patients with a single positive sentinel node.

The study included 3,619 patients from 79 institutions, enrolled from 1997 to 2003.

In a fairly complex protocol, the study evaluated the role of high-dose interferon-alpha2b or CLND in patients with melanoma, classified by SLNB.

Patients who were SLN-negative by standard testing underwent RT-PCR to look for melanoma-specific mRNA.