Primary melanoma regression may not be associated with reduced metastasis

1. Regression of primary melanomas greater than 0.75mm was not significantly correlated with changes in sentinel node (SN) status. 

2. Increased melanoma regression was associated with axial location and lesser Breslow thickness. 

Evidence Rating Level: 2 (Good)            

Study Rundown: Primary melanoma regression, likely due to inflammatory immune response, presents with reduced number of neoplastic cells and increased fibrosis, neovascularization, and inflammatory infiltrate.  Previous studies on its association with tumor metastasis have resulted in various conclusions.  Therefore, this study sought to determine whether primary melanoma regression in lesions greater than 0.75mm was associated with changes in SN status, and thus tumor metastasis.  The authors concluded that the presence or absence of tumor regression was not significantly associated with SN status and metastasis.  However, axial (head, neck, and trunk) location of the primary melanoma and lesion thickness of 1.00mm or less was statistically associated with regression.  Strengths of this study included its discussion of lesion thickness and previously reported associations with SN metastasis.  Future studies may include larger and more diverse patient populations, as well as primary melanomas smaller than 0.75mm.

Click to read the study in JAMA Dermatology

Relevant Reading: Favourable prognostic role of regression of primary melanoma in AJCC stage I-II patients

In-Depth [retrospective cohort]: This study assessed 201 melanomas in 201 patients at the Instituto Valenciano de Oncologia between January 1, 2003 and December 31, 2010.  Regressed lesions of greater than 0.75mm were categorized as either early or late regression, based on changes in melanoma cells and extent of fibrosis.  Primary melanomas were also characterized by binary variables such as age, sex, tumor location, ulceration, tumor infiltrating lymphocytes, Breslow thickness, mitotic index, extension of regression, and clinicopathic type, and analyzed using the χ2 test.  Results indicated no statistically significant relationship between melanoma regression and SN biopsy metastasis (P = 0.17).  However, Breslow thickness, mitosis, and clinicopathologic type was correlated with SN status (P = <0.001, 0.008, and <0.001 respectively).  Lastly, axial location of primary melanoma was found to be associated with regression (P = <0.001).

Image: PD 

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