Background: Malignant melanoma is the skin cancer with the highest mortality rate. In early stages, it may have a better prognosis and some possibility of cure. In Colombia, given the increase in cases, a national registry of the disease has been initiated with the aim of characterizing the population and establishing the prognostic factors in the local context. Methods: Cohort study based on data from the Epidemiological Registry of Malignant Melanoma in Colombia (REMMEC). For this first phase,data from January 2011 to December 2021 were analyzed. Patients were older than 18 years, with confirmed diagnosis of localized melanoma. Mortality and recurrence incidence rates were calculated using the Kaplan-Meier method, overall survival was estimated at 5 years of follow-up for each stage. Finally, a prognostic model was made for the mortality outcome, using the Cox proportional hazards method. Results: 759 patients were included, the mean age was 66 years (SD: 15.6), 57% women (n = 431), 29% phototype I or II (n = 219), and the most frequent histological subtype was acral lentiginous (n = 211; 36%). In relation to the stage, 13.9% with stage 0 (n = 106), 24.2% in stage I (n = 184), 30% in stage II (n = 228), and 31.7% in stage III (n = 241). ECOG-3-4 in 1.05% (n = 8). Regarding the health regimen, the subsidized patients were 199 (26%), and the contributive 560 (73.8%), of which 35 and 30.6% had stage III, respectively. 92% of all patients underwent local surgery (n = 699) and 30% (n = 226) local lymphadenectomy. The median follow-up time was 36 months (IQR: 17-72). The mortality incidence rate was 3.6 cases per 100 person-years (95% CI: 2.9-4.3), and the recurrence rate was 6.8 cases per 100 person-years (95% CI: 5.9 -7.8). Overall survival at five years for patients in stage 0 and I was 97% (95% CI: 89-99), for stage II it was 80% (95% CI: 72.6-86.6); for stage III 65% (95% CI: 57-72). 22.4% (n = 170) received adjuvant treatment . 26.2% (n = 199) had metastatic recurrence. The prognostic factors for mortality are presented in Table. Conclusions: In the Colombian context, in patients with localized melanoma, ECOG 3 or 4, stage III at the time of diagnosis, receiving radiotherapy, the presence of ulceration, chronic sun exposure, and the subsidized health regimen are poor prognostic factors.

*Subsidized health plan in Colombia is for patients without economic resources and low income level.