Factors influencing the linear depth of invasion of primary basal cell carcinoma

Predicting subclinical growth of basal cell carcinoma (BCC) is important for clinicians to determine adequate surgical margins. However, few attempts to predict the depth of invasion of BCC prior to surgery have been done.

To identify the factors significantly influencing the depth of invasion of primary BCC.

In 235 primary BCCs treated with surgical excision, maximum vertical diameter, designated as "invasion index," from the surrounding skin surface to the bottom of the tumor was measured. Multiple linear regression analysis was used to identify the factors significantly influencing the invasion index. Seven variables including age, sex, duration, anatomic location, tumor horizontal diameter, histologic subtypes, and ulceration were entered into the model.

Among seven variables, male sex (P = 0.0003), larger tumor diameter (P = 0.0011), and histologic subtypes including infiltrative, morpheic, and micronodular subtypes (P = 0.0019) had significant strength of influence for the invasion index.

The three predictive factors positively related to the linear depth of invasion in this study are important, but not sufficient, considerations at planning of surgery and for postoperative follow-up of BCC.