Predictors of Local Invasion in Infiltrative Basal Cell Carcinoma: Tumour Budding Outperforms the WHO Subtyping

Area of Science:

• Dermatopathology
• Oncology
• Surgical Pathology

Background:

• Tumour budding (TB) is associated with increased local invasion in various cancers.
• Certain basal cell carcinomas (BCCs) display local aggressiveness, necessitating identification of prognostic factors.
• Early detection of high-risk BCCs in partial biopsies can improve patient management.

Purpose of the Study:

• To evaluate the correlation between tumour budding (TB) and clinicopathological features in basal cell carcinoma (BCC).
• To determine the prognostic value of TB in predicting local invasiveness of BCC.
• To assess the utility of TB as a biomarker for guiding BCC treatment strategies.

Main Methods:

• Histopathological evaluation of 271 infiltrative BCC excision specimens.
• Quantification of tumour budding (TB) foci (absent, 1-2 foci, ≥3 foci, ≥10 foci).
• Analysis of correlation between TB, depth of infiltration, perineural invasion, and WHO histological subtypes using statistical methods including multiple regression.

Main Results:

• A significant correlation was observed between tumour budding (TB) and both depth of infiltration (rho 0.445, p < 0.001) and perineural invasion (p = 0.009).
• In multivariate analysis, TB was a significant covariate for depth of infiltration and perineural invasion, alongside other factors.
• No correlation was found between WHO histological subtypes and depth of infiltration or perineural invasion.

Conclusions:

• Tumour budding (TB) is a valuable and independent biomarker for local invasiveness in basal cell carcinoma (BCC).
• Counting TB foci (≥3 foci) in BCC lesions is a straightforward method to identify cases with heightened local risk.
• This finding can guide treatment decisions, particularly for incompletely excised BCCs or those with narrow tumour-free margins.