Key points In patients with T1a melanoma near critical structures, is a narrow excision margin (5 mm) associated with local recurrence and melanoma-specific mortality? Findings In this cohort study of 1179 patients with T1a melanoma of the scalp, face, external genitalia, acral, periumbilical, or perineal areas, the weighted 10-year melanoma-specific mortality was 1.8% and 4.0%. 2% in those who underwent wide surgery (10 mm) and narrow excision (5 mm), respectively. The 10-year weighted local recurrence rate was 5.7% and 6.7% in the wide and narrow groups, respectively. Meaning The study finding indicated that 5 mm margins may be adequate for excision of T1a melanoma near critical structures. |
Importance
Melanoma guidelines recommend surgical excision with 10-mm margins for T1 melanoma. However, this procedure can be problematic in sites close to critical structures such as the scalp, face, external genitalia, acral, periumbilical and perineal areas.
Aim
To compare the results of wide (10 mm margins) versus narrow (5 mm margins) excision in patients with T1a melanoma near critical structures.
Design, environment and participants
This cohort study was a retrospective comparison of 1341 consecutive patients aged 18 years or older from the National Cancer Institute of Milan, Italy, diagnosed between 2001 and 2020 with T1a cutaneous melanoma near critical structures who accepted wide excision vs. narrow cleavage.
Exhibitions
Local recurrence and melanoma-specific mortality (MSM) rates with 5 mm versus 10 mm excision margins.
Main results and measures
The primary objective of the study was to determine whether a narrower excision margin (5 mm) versus a wider excision margin (10 mm) was associated with local recurrence and MSM.
The secondary objective was to compare the need for reconstructive surgery in groups defined by excision margin width. Between April 28 and August 7, 2022, associations were assessed using univariable and multivariable weighted Cox and Fine-Gray models.
Results
A total of 1179 patients met the inclusion criteria (median [IQR] age, 50.0 [39.5-63.0] years; women, 610 [51.7%]; men, 569 [49.3%] ]).
Six hundred twenty-six patients (53.1%) received a wide excision (434 [69.3%] with linear repair and 192 [30.7%] with flap or graft reconstruction) and 553 (46.9%) received an excision narrow (491 [88.8%] with linear repair and 62 [11.2%] with flap or graft reconstruction).
Weighted 10-year melanoma-specific mortality ( MSM) was 1.8% (95% CI, 0.8%-4.2%) in the broad group and 4.2% (95% CI, 0.8%-4.2%) in the broad group and 4.2% (95% CI, 2.2%-7.9%) in the reduced group; The 10-year weighted local recurrence rate was 5.7% (95% CI, 3.9%-8.3%) in the broad group and 6.7% (95% CI, 4.7% %-9.5%) in the small group.
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 < 0.001) and a mitotic rate greater than 1/mm 2 (sHR for single increment, 3.35; 95% CI, 2.59-4.32; P < 0.001) were associated with worse MSM.
Multivariate analysis showed that acral lentiginous melanoma, lentigo maligna melanoma, and increased Breslow thickness were associated with a higher incidence of local recurrence.
Conclusions and relevance
- The study findings suggest that local excision with 5 mm margins for T1a melanoma may not be associated with an increased risk of local recurrence.
- Breslow thickness greater than 0.4 mm, mitotic rate greater than 1/mm 2, and acral lentiginous melanoma and lentigo maligna melanoma subtypes were associated with an increased risk of recurrence.
- These findings may be useful for future melanoma treatment guidelines.
