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Weekly UpdatesORLANDO -- Long-term follow-up data on patients with melanoma suggest that minimal sentinel lymph node tumor burden at diagnosis predicts excellent melanoma-specific survival, with a prognosis indistinguishable from that in patients who are sentinel node negative, European investigators reported at the annual meeting of the American Society of Clinical Oncology.
"In the group of submicrometastases we have a couple of events up to 5 years, which leads to a 94% 5-year melanoma-specific survival [rate], but in the period from 5 to 10 years we saw no further events, so this was still 94% at 10 years, estimated," said Dr. Alexander van Akkooi of Erasmus University Medical Center in Rotterdam, the Netherlands.
The findings, coupled with data showing a very low rate of positive lymph nodes on completion lymph node dissection (CLND), also suggest that patients with minimal sentinel node burden might be spared CLND, said Dr. van Akkooi, speaking on behalf of colleagues in the European Organization for Research and Treatment of Cancer (EORTC) Melanoma Group.
The EORTC investigators conducted a retrospective study of tumor slides from 595 patients with melanoma and positive sentinel nodes.
They reviewed the slides for the microanatomical location of the tumor within sentinel nodes, and for total sentinel node burden according to the Rotterdam criteria, which group tumors into three categories based on the maximum diameter in any direction of the largest lesions in a given node. The categories are tumors smaller than 0.1 mm, tumors measuring 0.1-1.0 mm, and tumors greater than 1.0 mm in diameter.
Looking at other tumor criteria in the 595 samples, they found a median Breslow thickness of 3.4 mm (overall mean, 4.7 mm). In all, 67 patients (11%) had sentinel node metastases smaller than 0.1 mm in diameter, 226 (38%) had lesions 0.1-1.0 mm in diameter, and 302 (51%) had metastases greater than 1.0 mm. For all patients, mean and median follow-up were 40 and 48 months, respectively.
The 5-year melanoma-specific rates were 94% for those metastases smaller than 0.1 mm, compared with 70% for lesions 0.1-1.0 mm in diameter, and 57% for those larger than 1.0 mm.
In multivariate analysis, significant predictors for worse prognosis included stage T4 primary tumors, presence of tumor ulceration, location of the tumor within the sentinel node, and tumor burden. The hazard ratio for sentinel node tumors 0.1-1.0 mm in diameter, compared with those smaller than 0.1 mm, was 4.2, and for the largest tumors it was 5.1.
Dr. van Akkooi had no conflicts of interest to disclose.
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