Melanoma Excisions with 5 Millimeter Margins Linked to Less Risk of Local Recurrence

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New study data re-evaluating current guidelines for T1a melanoma excisions indicate that 5-mm margins may be adequate in order to maintain lower risk levels for melanoma recurrence.

A T1a melanoma excision near critical structures with 5-mm margins may be adequate for a diminished risk of local recurrence compared to other excisions, according to recent findings.1

This research was conducted to re-assess the current guidelines recommending surgically removing T1a melanomas with 10mm margins, despite the proximity to important facial structures such as the face, acral, scalp, genitalia, periumbilical, and perineal areas.2

This study, authored by Andrea Maurichi, MD, from the Melanoma Surgical Unit at Fondazione IRCCS Istituto Nazionale dei Tumori di Milano in Italy, compared outcomes from wider and narrower-margin excisions in those with T1a melanoma by critical areas of the body.

“We retrospectively assessed patients who declined WLE with a 10-mm margin in favor of a 5-mm margin and compared outcomes in these 2 groups,” Maurichi said. “We confined our attention to T1a melanomas because the clinical behavior of these lesions may be similar to that of in situ melanomas for which WLE with a 5-mm margin is acceptable.”

Background and Findings

In their cohort study, the investigators included participants who were 18 years of age or older and had been given consecutive treatments at the National Cancer Institute in Milan, Italy, in the period between 2001 and 2020.

Those who the researchers recruited for the study had localized T1a primary cutaneous melanoma in areas such as the face and head with either cosmetic or functional issues, acral areas such as palms of the hand and foot soles, external genitalia, or periumbilical and perineal regions.

The research team sought to examine the impacts of 2 different types of excision margin widths (5-mm versus 10-mm) on both local recurrence and on melanoma-specific mortality (MSM) rates in study participants. The team also aimed to compare the requirement for reconstructive surgery between both arms of the study.

The investigators used weighted Cox and Fine-Gray univariable and multivariable models to evaluate the associations between different variables in the study, and the research was conducted between April and August of 2022.

In the end, the researchers had a total of 1179 study participants and a median age of 50.0 years. Among these participants, 51.7% were reported to be female and 49.3% were male.

Of the group of 1179 participants, 53.1% were given a wide excision (10-mm). In this group, 434 were given a linear repair and 192 were given flap or graft reconstruction. The remaining 46.9% of the participants received a narrow excision (5-mm), with 491 being given linear repair and 62 being given flap or graft reconstruction.

Overall, the investigators reported that the weighted 10-year MSM was found to be 1.8% (95% CI, 0.8% - 4.2%) for the wide excision arm of the study and 4.2% (95% CI, 2.2% - 7.9%) for the narrow excision arm.

They added that the weighted 10-year local melanoma recurrence rate was 5.7% (95% CI, 3.9% - 8.3%) in the wide arm and 6.7% (95% CI, 4.7% - 9.5%) for the narrow arm.

The investigators added that a Breslow thickness greater than 0.4 mm (subdistribution hazard ratio for 0.6 versus 0.4 mm, 2.42; 95% CI, 1.59 - 3.68; P < .001) and a mitotic rate greater than 1/mm2 (sHR for a single increment, 3.35; 95% CI, 2.59 - 4.32; P < .001) were both found to be linked to worse MSM.

Higher incidence rates of local occurrence were also found, in the team’s multivariate analysis, to be linked to lentigo maligna melanoma, acral lentiginous melanoma, and increasing Breslow thickness.

“Because this association was found in melanomas of the head and neck, acral, and genital sites, there is no plausible reason why it could not be extrapolated to other locations,” they wrote. “The findings also support the need for prospective randomized clinical trials to definitively answer the important question about appropriate excision margins for T1a melanoma.”


  1. Maurichi A, Barretta F, Patuzzo R, et al. Association of Excision Margin Size With Local Recurrence and Survival in Patients With T1a Melanoma at Critical Structures. JAMA Dermatol. Published online April 12, 2023. doi:10.1001/jamadermatol.2023.0620.
  2. Melanoma cutaneous (version 2.2022). National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology. Accessed May 8, 2022.