Clinical tumor factors that may contribute individually or in combination to a basal cell carcinoma (BCC)to be regarded as locally advanced include:

• Tumor size and location, and cosmetic and functional consequences of treatment
• Numerous coexisting tumors
• Tumor subtype
• Likelihood of successful treatment compromised by previous treatment 

Surgical treatment guidelines include:

• Standard surgical excision should be considered as a first-line treatment option to adults with low-risk BCC.
• Standard surgical excision with delayed definitive reconstructionor Mohs micrographic surgery should be deemed as a first-line treatment option to adults with high-risk BCC – within a high-risk anatomical site,with poorly defined clinical margins under bright lighting and magnificationor dermoscopy.
• Low-risk BCC must be excised using a 4 mm peripheral clinical surgical margin.
• Primary BCC should be excised with a high-risk factorusing at least a 5 mm peripheral clinical surgical margin.
• BCC should be excisedadequately at the deep margin to a clear planeand other deeper structures if needed.
• Mohs micrographic surgery should be deemed as an option for adults with primary BCC with at least one high-risk factor.
• Mohs micrographic surgery can be considered a first-line treatment option for adults with recurrent and advanced BCC with at least one other high-risk factor, in particular, if the tumor is at a high-risk site.
• Following discussion at a multidisciplinary team (MDT), standard surgical excision with at least a 5 mm margin may be considered, followed by a delayed definitive reconstruction as a treatment option in adults with recurrent BCC with at least one other high-risk factor.
• Standard surgical excision or radiotherapy could be a treatment option for adults with advanced BCC.

Source: The British Journal of Dermatology. 2021 Nov;185(5):899-920. doi: 10.1111/bjd.20524.