Correlation Between Demographic and Tumor Characteristics in Non-melanoma Skin Cancers Submitted to Mohs Micrographic Surgery

Abstract

Background/aim: Non-melanoma skin cancer (NMSC) is the most prevalent type of cancer in adults. Surgery remains the golden-standard treatment for this disease. Mohs micrographic surgery (MMS), a surgical technique, is based on the three-dimensional histopathological examination of the margin and surgical bed, layer by layer, in the excised tissue allowing for the determination of the location of the residual tumor, for its complete excision, with high cure rates and preservation of the unaffected tissue. The aim of this study was to present the epidemiological characteristics of the population that was submitted to MMS, as well as, correlate these characteristics with the characteristics of the tumor itself and the surgical procedure.

Patients and methods: A retrospective cross-sectional study was conducted over a 10-year period with an analysis of patient medical records submitted for MMS at the Department of Dermatology of the ABC School of Medicine. Data were presented and evaluated by non-parametric and parametric analyses, using absolute and relative frequency values for the continuous variable, to which a Chi-square test was applied for the verification of power with a significance level of 5%. For the independent variables, the Student's t-test was used to compare means, with a confidence interval (CI) ranging from 95 to 99%, and Friedman's test was used to verify if there were significant differences in the variables of interest.

Results: Female patients accounted for 67% of all enrolled patients (n=335). The mean age was 67 years (SD±12.04; median=68; range=25-93 years). The predominant skin phototype (Fitzpatrick's classification) was phototype II (n=228, 46%). All procedures were performed under local anesthesia. Flap reconstruction was the most predominant surgery type (n=17, 68%). The mean number of MMS's stages was 1.6 (range=1-8). There was a mean of 3.8 fragments of skin tissue (range=1-29) per stage. The mean tumor size was 30 mm (92%). This was associated with female sex (p=0.03), H-zone area (p<0.001), flap reconstruction (p=0.004), tumor removal 7 to 12 months after diagnosis (p<0.001) and non-recurrence tumors (p=0.02).

Conclusion: NMSCs were frequently observed in older women with skin phototypes II/III. Reconstruction of the primary defect was feasible under local anesthesia, even in tumors with a marked diameter, decreasing the morbidity of this surgery, providing very satisfactory functional and aesthetic results, reduction costs and ease of access to the surgical procedure.

Keywords: Mohs micrographic surgery; Non-melanoma skin cancer; epidemiology.