Basal cell carcinoma: histological classification and body-site distribution.

Area of Science:

• Dermatology
• Oncology
• Epidemiology

Background:

• Basal cell carcinoma (BCC) is the most prevalent cancer in fair-skinned populations globally.
• Emerging research indicates BCC heterogeneity, with distinct subtypes exhibiting varied clinical behaviors and potential etiologies.

Purpose of the Study:

• To determine the incidence rates of BCC stratified by histopathological subtype and anatomical location.
• To investigate the distribution patterns of different BCC subtypes across various body sites.

Main Methods:

• A prospective, population-based case series of BCCs was analyzed.
• Data were collected from a registry of all excised, histologically confirmed skin cancers in Townsville, Australia, between 1997 and 1999.

Main Results:

• Age-standardized incidence rates per 100,000 inhabitants/year were: nodular BCC (727.1 males, 411.8 females), superficial BCC (336.5 males, 251.4 females).
• 'High-risk' subtypes showed rates of infiltrative BCC (261.3 males, 146.5 females) and micronodular BCC (156.7 males, 100.2 females).
• Tumor density was highest on the face, followed by the neck for most subtypes, with an exception for superficial BCC in males (posterior trunk second). Superficial BCC occurred at younger ages, particularly in females.

Conclusions:

• This study observed a higher incidence of superficial BCC than reported in studies from less sun-exposed regions, with a more even distribution across the face, trunk, and limbs.
• The findings suggest a potential blurring of distinctions between intermittent and continuous sun exposure as primary causative factors.
• Clinical implications of 'high-risk' BCC incidence rates are discussed.