<b><i>Background:</i></b> Large prospective studies on the safety of Mohs micrographic (MMS) surgery are scarce, and most focus on a single type of surgical adverse event. Mid-term scar alterations and functional loss have not been described. <b><i>Objectives:</i></b> To describe the risk of MMS complications and the risk factors for them. <b><i>Methods:</i></b> A nationwide prospective cohort collected all adverse events on consecutive patients in 22 specialised centres. We used multilevel mixed-effects logistic regression to find out factors associated with adverse events. <b><i>Results:</i></b> 5,017 patients were included, with 14,421 patient-years of follow-up. 7.0% had some perioperative morbidity and 6.5% had mid-term and scar-related complications. The overall risk of complications was mainly associated with use of antiaggregant/anticoagulant and larger tumours, affecting deeper structures, not reaching a tumour-free border, and requiring complex repair. Age and outpatient setting were not linked to the incidence of adverse events. Risk factors for haemorrhage (0.9%) were therapy with antiaggregant/anticoagulants, tumour size, duration of surgery, and unfinished surgery. Wound necrosis (1.9%) and dehiscence (1.0%) were associated with larger defects and complex closures. Immunosuppression was only associated with an increased risk of necrosis. Surgeries reaching deeper structures, larger tumours and previous surgical treatments were associated with wound infection (0.9%). Aesthetic scar alterations (5.4%) were more common in younger patients, with larger tumours, in H-area, and in flap and complex closures. Risk factors for functional scar alterations (1.7%) were the need for general anaesthesia, larger tumours that had received previous surgery, and flaps or complex closures. <b><i>Conclusions:</i></b> MMS shows a low risk of complications. Most of the risk factors for complications were related to tumour size and depth, and the resulting need for complex surgery. Antiaggregant/anticoagulant intake was associated with a small increase in the risk of haemorrhage, that probably does not justify withdrawal. Age and outpatient setting were not linked to the risk of adverse events.
Randomized studies to assess the efficacy of Mohs micrographic surgery in basal cell and squamous cell carcinomas are limited by methodological and ethical issues and a lack of long follow-up periods. This study presents the “real-life” results of a nationwide 7-years cohort on basal cell carcinoma and squamous cell carcinoma treated with Mohs micrographic surgery. A prospective cohort was conducted in 22 Spanish centres (from July 2013 to February 2020) and a multivariate analysis, including characteristics of patients, tumours, surgeries and follow-up, was performed. A total of 4,402 patients followed up for 12,111 patient-years for basal cell carcinoma, and 371 patients with 915 patient-years of follow-up for squamous cell carcinoma were recruited. Risk factors for recurrence included age, non-primary tumours and more stages or unfinished surgeries for both tumours, and immunosuppression for squamous cell carcinoma. Incidence rates of recurrence were 1.3 per 100 person-years for basal cell carcinoma (95% confidence interval 1.1–1.5) and 4.5 for squamous cell carcinoma (95% confidence interval 3.3–6.1), being constant over time (0–5 years). In conclusion, follow-up strategies should be equally intense for at least the first 5 years, with special attention paid to squamous cell carcinoma (especially in immunosuppressed patients), elderly patients, non-primary tumours, and those procedures requiring more stages, or unfinished surgeries.
Background
The two main tumors treated with Mohs micrographic surgery (MMS) are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). There are no studies analyzing whether MMS is different when treating these two types of tumors.
Objective
We aim to compare the characteristics of the patients, the tumors, and MMS, and first‐year follow‐up of MMS in BCC and SCC.
Methods
REGESMOHS is a prospective cohort study of patients treated with MMS. The participating centers are 19 Spanish hospitals where at least one MMS is performed per week. Data on characteristics of the patients, tumors, and surgery were recorded. The follow‐up was done with two visits: the first visit within 1 month after surgery and the second one within the first year.
Results
From July 2013 to April 2017, a total of 2,669 patients who underwent MMS were included in the registry. Of them, 2,448 (93%) were diagnosed with BCC, and 181 (7%) were diagnosed with SCC. Patients with SCC were older than those with BCC (median age 73 years vs. 68 years) and presented immunosuppression more frequently. The tumor size was significantly larger in the SCC group. Regarding surgery, deeper invasion was more frequent in SCC, resulting in larger defects. Despite this, SCC did not require more stages to get clear margins or more time in the operating room. Incomplete Mohs was more frequent in the SCC group (6%) than in the BCC group (2%). The incidence of perioperative complications was higher when treating SCC. There were more relapses in the first‐year follow‐up in the SCC group.
Conclusion
There are significant differences when comparing MMS in BCC and SCC. Knowledge of these differences can help to prepare the patient and plan the surgery, optimizing results.
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