Risk factors for incomplete excision of cutaneous squamous cell carcinoma: a large cohort study.

Background: The standard treatment for cutaneous squamous cell carcinoma (cSCC) is surgical excision. Failure to radically remove a cSCC is a risk for recurrence, progression and metastasis.

Objectives: This study investigates several risk factors for incomplete excision of cSCC.

Methods: All consecutive patients in a single institution treated with wide local excision for primary cSCC over a 10-year period were included in this study. Risk factors such as: gender, age, immunosuppression, tumour size, location, differentiation grade, tumour depth, perineural and lymphovascular invasion (PNI and LVI) were extracted from the database. Univariable and (if applicable) multivariable logistic regression analysis were used to identify risk factors (P < 0.05). Generalized estimating equations (GEEs) were used for multiple tumours within the same patients.

Results: A total of 566 patients with 1159 cSCC were identified. Univariable and multivariable logistic regression analysis showed that depth beyond the dermis (OR: 5.7 95% CI: 3.1-10.5) was the only risk factor for incomplete excision of cSCC. Immunosuppression was only a risk factor in the deep plane (OR: 2.5, 95% CI: 1.3-4.6).

Conclusion: Tumour depth beyond the dermis is the most important risk factor for incomplete excision of cSCC. Immunosuppression is a risk factor in the deep plane but its relevance is uncertain. Immunosuppression is not consistently included in the current cSCC staging systems, but care should be taken when treating these patients.