Fox lecture: Sentinel node biopsy continues to stir debate
|Timothy M. Johnson, M.D.
Sentinel node biopsy has been used for the prognosis and staging of melanoma patients for more than 20 years, and a mountain of data has been collected. Still, the pros and cons of the procedure are at times hotly discussed, a debate that was reviewed in Friday's Everett C. Fox, M.D., Memorial Lectureship.
"The value and acceptance of the procedure for patients with melanoma remains a controversial issue for some, with disparity in practice — primarily in the specialty of dermatology," Timothy M. Johnson, M.D., said in his lecture, "Sentinel Node Biopsy: Just the Facts, You Decide."
Dermatologists are critical for the diagnosis, counseling and management of patients with melanoma and they need to be aware of the current — and sometimes rapidly changing — body of new and evolving information, he said.
Pros and cons of sentinel node biopsy
"On opposing sides, the arguments are both real and theoretical, with benefits of the procedure juxtaposed against reasonable and justifiable concerns that have been raised by critics. Several questions remain unanswered, and ongoing trial results may or may not support all of the reasons for considering and performing sentinel node biopsy today," said Dr. Johnson, Lewis and Lillian Becker Professor of Dermatology at the University of Michigan Health System, Ann Arbor.
The irony is, this is a moot point when treating most patients diagnosed with melanoma. The majority of patients diagnosed with melanoma are diagnosed with thin lesions or already have clinically evident metastasis, and thus, should not be good candidates for sentinel node biopsy under current treatment guidelines.
Uses for sentinel node biopsy
Dr. Johnson covered arguments on both sides of the debate, but stressed that the greatest strength of sentinel node biopsy is accurate staging of the clinically negative regional lymph node basin in appropriate candidates.
"The proven reason today to use sentinel node biopsy is for prognosis and staging, which is often invaluable to patients with melanoma and guides treatment decisions. Nobody argues about prognosis," he said. "The other reasons to consider it are that it may provide better durable regional disease control and potential
for survival or outcome benefit in node-positive patients."
Inadequacies of sentinel node biopsy
Still, there are several reasons to not use sentinel node biopsy.
"The first reason is a low probability of a positive sentinel node biopsy," Dr. Johnson said. "The second reason is if a patient has significantly high medical comorbidities. The third reason is following a wide local excision in areas of ambiguous lymphatic drainage or following a local flap, where the accuracy of sentinel node biopsy will be decreased." The debate over sentinel node biopsy has changed greatly over the last two decades as more data were collected, and it is expected to shift again when the next analysis of data from the Multicenter Selective Lymphadenectomy Trial-1 (MSLT-1) is released in the next few years, he said.
More research to come
"The fourth of five interim analyses (of trial data) is being done now, and hopefully it will answer several questions more definitively," Dr. Johnson said. "We have learned so much with a tremendous amount of research and advances, yet there is still so much more to be learned, and the guidelines are a moving target as new data is produced.
"What we say today could, and likely will, change tomorrow, and it will probably change significantly pro or con, depending on the data as soon as the fourth interim analysis of the MSLT-1 trial is released. One thing that won't change is the critical importance of dermatology with the need to remain current in the field of melanoma. National consensus guidelines will continue to evolve, and must be fluid and adapt to the changing landscape of research knowledge."