VANCOUVER, B.C. — According to an informal poll, most melanoma experts would want a sentinel node biopsy if they had melanoma, despite the fact that sentinel node biopsy results have now been followed out for 5 years, and were not shown to increase long-term survival.
The poll was taken by Merrick Ross, M.D., at the Sixth World Congress on Melanoma, following a presentation of the 5-year results of the 1,973-subject, Multicenter Selective Lymphadenectomy Trial.
The Multicenter Selective Lymphadenectomy Trial found no statistically significant difference in 5-year survival rates between those who had sentinel node biopsy and those who did not (87% vs. 86%), the primary end point of the trial, said Donald L. Morton, M.D., the originator of the procedure. Dr. Morton is the chief of science and medicine at the John Wayne Cancer Institute, Santa Monica, Calif.
However, subanalysis of the data from the trial suggested enough benefit that if sentinel node biopsy were considered a new drug, it would warrant Food and Drug Administration approval, Dr. Morton asserted.
One of the commentators, John Thompson, M.D., said he agreed. Assessment of the sentinel node for evidence of migrating melanoma cells “is likely to be appropriate and important for the foreseeable future,” said Prof. Thompson, executive director of the Sydney Melanoma Unit at the Royal Prince Alfred Hospital, Camperdown, Australia, and another principal investigator in the trial.
The other commentator, however, disagreed strongly. The trial was designed to look for a difference in survival, and it failed to show one, said J. Meirion Thomas, M.D., of the sarcoma unit of the Royal Marsden Hospital, London. “We must stop burying our head in the sand,” Dr. Thomas said. “At the present time, this procedure offers patients no benefit.”
Dr. Ross, chief of the melanoma section at the M.D. Anderson Cancer Center, Houston, and an advocate of the procedure, asked the approximately 200 melanoma experts present in the room: “If you had melanoma, would you want a sentinel node procedure?” About 90% of the audience raised their hands, indicating they would.
The Multicenter Selective Lymphadenectomy Trial looked at patients who had melanomas with greater than a 1.0-mm Breslow thickness. It randomized about 60% of the patients to wide local excision with a sentinel node biopsy, which was followed by regional lymphadenectomy if a positive sentinel node was found. About 40% of the patients were randomized to a watch-and-wait group, in which they received a wide local excision only, and were followed. If the followed patients developed a palpable node, they then underwent regional lymphadenectomy. The median time of follow-up of the patients was 59 months.
Although there was no difference in overall survival, there was a difference in disease-free survival (78% vs. 73%), Dr. Morton said.
The analysis also showed that there was a similar rate of positive nodes in both groups (16%); that node positive patients overall had lower survival at 5 years (71% vs. 88%); and that when patients needed regional lymphadenectomy, those in the sentinel node biopsy group had fewer positive nodes at lymphadenectomy than did those in the watch-and-wait group (an average 1.6 vs. 3.4), among other findings.
Moreover, 5-year survival among those with positive nodes was significantly higher in those patients with a positive sentinel node and immediate lymph node dissection than it was among the patients who had a delayed complete dissection (71% vs. 55%).
Taking the data all together, no evidence suggested that the sentinel node biopsy was inaccurate, or that it was unsafe in any way. The data further suggested that there were some patients whose disease was caught while it was still limited to the sentinel node, and that these patients were cured, Dr. Morton said.
“There is a very short window of opportunity here where in fact there is a small, but definite subset of patients who have their disease limited to the sentinel node, and their removal aborts the blood-borne and distant metastasis,” he said.
Sentinel node biopsy is important also because it removes uncertainty for many patients, and it allows for more accurate cancer staging of patients, which is critical information for conducting clinical trials, he added.
The reason the trial may have shown no effect on overall survival may be because it enrolled too few patients to make a clear difference, Prof. Thompson suggested.
Dr. Morton agreed. The $90-million trial has had far fewer deaths (13%) than were expected when the trial was designed over a decade ago, when the only information they had to go on to decide how many patients might be needed was the historical rate at the John Wayne Cancer Institute, he said.