Three clinical factors help estimate which thin melanomas are likely to harbor occult nodal metastases, and thus aid in selecting which patients would benefit most from sentinel node biopsy, according to a report in the February issue of the Archives of Surgery.
The three factors--patient sex, patient age at diagnosis, and lesion Breslow thickness--were used to develop a scoring system for estimating the risk of nodal recurrence. "This risk assessment is not intended to mandate what risk level is appropriate for sentinel node evaluation, but it allows for a better informed discussion with the patient newly diagnosed as having melanoma.
"Such information could be used to reassure extremely low-risk patients who may be anxious about the possibility of metastases or convince patients at higher risk of the need to consider biopsy," said Dr. Mark B. Faries of the John Wayne Cancer Institute, Santa Monica, Calif., and his associates (Arch. Surg. 2010;145:137-42) .
The use of sentinel node biopsy in patients with thin melanoma is controversial, since most such cases are at low risk for metastasis but the disease is usually fatal for the few patients who do develop recurrence. Doing the procedure in every case "would be prohibitively expensive and would expose a large number of patients with an extremely low risk of nodal disease to the real, albeit low, risk of toxic effects related to the procedure," they noted.
Dr. Faries and his colleagues reviewed the records in a prospective database of over 13,000 cases of thin (<1 mm) melanoma treated in 1971-2005 with wide excision but no nodal staging or lymphadenectomy. A total of 1,732 subjects were enrolled in the study. They were followed every 3 months for 2 years, every 4-6 months for the next 3 years, and annually thereafter.
During a median follow-up of 13 years, 51 patients (3%) developed nodal metastases. The median time to such recurrence was 38 months.
A variety of clinical factors were assessed to identify which ones were the strongest predictors of metastasis. Male sex, younger age at diagnosis, and greater tumor Breslow thickness were strongly predictive of metastasis, while factors such as tumor site and Clark level were not.
The investigators developed a scoring system using these 3 factors. Applying it to the study subjects, they found that the system predicted a 0.1% risk of metastasis in the lowest-risk subjects, compared with predicting a 17% risk of metastasis in the highest-risk subjects.
Tumor ulceration was predictive of nodal recurrence, with an 8% rate of metastasis in cases of ulcerated lesions compared to a 3% rate in cases without ulceration. However, ulceration was not included in the scoring system because information on ulceration often was not included in patient records, and a small proportion (approximately 2%) of this subset of patients showed lesion ulceration.
"Although such ulcerated lesions clearly deserve greater concern and evaluation, the rarity of this finding decreases the utility of including it in a prediction scheme," Dr. Faries and his associates said.
This study was funded in part by the National Cancer Institute and the Amyx Foundation. No financial conflicts of interest were reported.