Narrow margin excision of T1a melanoma not associated with recurrence or melanoma-specific mortality

1. Wide local excision of T1a melanoma near critical structures with narrow (5-mm) margins was not associated with worse outcomes.

2. Fewer reconstructive surgeries were found in wide local excision of T1a melanoma near critical structures with narrow (5-mm) compared to wide (10-mm) margins.

Evidence Rating Level: 2 (Good)

Study Rundown: Surgical excision is recommended for T1 melanoma with 10-mm margins; however, this recommendation may cause additional problems in areas close to critical structures (e.g., the scalp, face, external genitalia, acral, periumbilical, and perineal areas). Thus, this retrospective cohort study compared the outcomes of wide (10-mm) and narrow (5-mm) margin excisions for T1a melanoma near critical areas. Recurrence and melanoma-specific mortality (MSM) rates were extracted from 1,179 patients over the age of 18 diagnosed between 2001 and 2020 from the National Cancer Insitute of Milan, Italy. In addition to local recurrence and MSM, the need for reconstructive surgery defined by excision margin width was explored. Local excision with narrow margins was not associated with an increased risk of local recurrence. Higher risks of recurrence were associated with Breslow thickness greater than 0.4 mm, a mitotic rate greater than 1/mm², acral lentiginous melanoma subtypes, and lentigo maligna melanoma subtypes. Furthermore, more patients in the wide-excision group required reconstructive surgery. Some strengths of this study included the large cohort of patients and long follow-ups. However, the study is limited by its retrospective nature and how the wide and narrow groups were defined by the patient’s decision to accept or refuse melanoma guideline recommendations. In addition, although all slides were examined according to a common protocol, the histopathological review was not centralized. Overall, the results did not find a significant association between narrow margins and worse outcomes; however, narrow margins were significantly associated with fewer reconstructive surgeries.

Click to read the study in JAMA Dermatology

Relevant Reading: Reducing margins of wide local excision in head and neck melanoma for function and cosmesis: 5-year local recurrence-free survival

In-Depth [retrospective cohort]: The inclusion criteria for this retrospective cohort study included patients aged 18 years or older diagnosed with localized T1a primary cutaneous melanoma of the head, face, acral, external genitalia, periumbilical, and/or perineal areas. Furthermore, the patients were required to have been treated between 2001 and 2020 at the National Cancer Insitute in Milan, Italy. 1,341 patients met the inclusion criteria; however, 162 patients were excluded due to missing data (85; 6.3%), patient history of additional invasive cancer other than basal cell carcinoma (38; 2.8%), patient diagnosis of primary mucosal melanoma (8; 0.6%), and incomplete excision margins after wide local excision (31; 2.3%). Age, sex, tumour site, melanoma subtype, vertical growth phase, Breslow thickness, mitotic rate per square millimetre, Clark level, tumour-infiltrating lymphocytes, lymphovascular invasion, and tumour regression was retrieved from a database for the total of 1,179 patients (median [IQR] age, 50.0 [39.5-63.0] years; female, 610 [51.7%]; male, 569 [49.3%]). Out of the 626 patients (53.1%) who received wide excisions, the linear repair was performed for 434 patients (69.3%)  and flap or graft reconstruction was performed for 192 patients (30.7%). Out of the 554 patients (46.9%) who received narrow excisions, linear repair was performed for 491 patients (88.8%)  and flap or graft reconstruction was performed for 62 patients (11.2%). The wide group had a weighted 10-year MSM of 1.8% (95% CI, 0.8%-4.2%), whereas the narrow group was 4.2% (95% CI, 2.2%-7.9%). The wide group had a weighted 10-year local recurrence rate of 5.7% (95% CI, 3.9%-8.3%), whereas the narrow group was 6.7% (95% CI, 4.7%-9.5%). MSM was found to be worse with Breslow thickness greater than 0.4 mm (subdistribution hazard ratio [sHR] for 0.6 vs 0.4 mm, 2.42; 95% CI, 1.59-3.68; P < .001) and with a mitotic rate greater than 1/mm² (sHR for a single increment, 3.35; 95% CI, 2.59-4.32; P < .001). Through a multivariable analysis, the incidence of local recurrence was associated with acral lentiginous melanoma, lentigo maligna melanoma, and increasing Breslow thickness. 62 patients (11.2%) in the narrow group and 192 (30.7%) in the wide group required reconstructive surgery (P < .001), suggesting that narrow margins may reduce scarring, poor healing, infection, and mental issues occurring with excisions close to critical areas. Overall, this retrospective cohort study found that treating primary T1a melanomas with narrow 5-mm margins was not significantly associated with worse outcomes; however, it was significantly associated with fewer reconstructive surgeries.

Image: PD

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