- The role of sentinel lymph node biopsy (SLNB) in patients with melanomas with regression is controversial, as is the prognostic significance. In a retrospective analysis of 1693 patients with stage I/II melanoma, results showed favorable disease-free and overall survival associated with regression in the primary melanoma. Further, the rate of those who later developed regional node involvement with a previously negative SLNB ("false negative SLNB") was lower in those with regression.
- Regression in melanoma appears to have a more favorable prognostic role than was previously thought, and the use of SLNB in patients with thin melanomas without additional risk factors does not appear necessary.
"These are fascinating data that fly in the face of the general sense that regression implies that the true Breslow depth would have been greater prior to regression, engendering an increased risk of metastases. There will likely be other datasets that can be evaluated or reevaluated to see if this holds true to help guide us in our care of melanoma patients. In the meantime, we will have to explain to patients that, when regression is present in thin melanomas, the data are not completely clear with respect to risks of metastasis and survival." – Eliot Mostow, MD
"It will be interesting to see how this finding holds up in other datasets and studies. If consistent, perhaps this may imply that regression signifies a good immunologic host response to the malignancy. However, this is speculative at this point." – Ashish Bhatia, MD
The prognostic significance of regression in primary melanoma has been debated over the past few years. Once it was considered to be a negative prognostic factor, as it may have prevented proper melanoma thickness measurement, therefore affecting the staging of the tumours. For this reason, it was considered to be an indication for sentinel lymph node biopsy (SLNB) in melanoma < 1 mm.
To ascertain the utility of SLNB in thin melanoma and to clarify the role of regression in disease-free survival (DFS) and overall survival (OS) in our series.
We analysed data collected from 1693 consecutive patients with AJCC (American Joint Committee on Cancer) stage I-II melanoma.
Globally, SLNB was performed in 656 out of 1693 patients. Regression was present in 349 patients and 223 of them were characterized by thin lesions. SLNB was performed in 104 cases of thin melanoma with regression. The majority of regional lymph node metastases were observed in patients who did not undergo SLNB (89 out of 132). Among the remaining 43 'false negative' patients only three showed regression in the primary. Using the Cox multivariate model, histological regression maintained a significant protective role [hazard ratio (HR) 0·62, P = 0·012 for DFS; HR 0·43, P = 0·008 for OS] when corrected for the principal histopathological and clinical features, despite SLNB.
We confirmed that regression alone should not be a reason to perform SLNB in thin melanoma and, on the contrary, it can be considered a favourable prognostic factor in patients with AJCC stage I-II melanoma.