Types of Skin Cancer
Skin cancer is classified into three primary types: basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma, with BCC and SCC collectively termed non-melanoma skin cancers (NMSC) or keratinocyte carcinomas. 1, 2
Primary Classification
Non-Melanoma Skin Cancers (Keratinocyte Carcinomas)
Basal Cell Carcinoma (BCC)
- Most common skin cancer across all racial and ethnic groups, accounting for approximately 4-5 times more cases than squamous cell carcinoma 1, 3
- Estimated 2 million cases annually in the United States 2
- Rarely metastatic but can cause substantial local destruction, disfigurement, and involvement of soft tissue, cartilage, and bone 1, 2
- Generally has excellent prognosis due to low metastasis rates 2
- Develops primarily on sun-exposed sites, especially the head and neck area 2
Squamous Cell Carcinoma (SCC)
- Second most common type of skin cancer 1, 4
- More aggressive than BCC with higher metastatic potential 5
- Accounts for more skin cancers in individuals with darker skin tones 3
- Can develop de novo, from pre-existing lesions (like Bowen's disease), or in chronic wounds, scars, burns, or areas of prior radiation 4
- Associated with chronic, cumulative UV exposure over decades 6
Melanoma Skin Cancer (MSC)
Cutaneous Melanoma
- Represents approximately 1% of all skin cancers but causes the most skin cancer deaths 7
- Estimated 8,000 deaths in the US in 2023 7
- About 30 times more common in White persons than Black persons 7
- Critical disparity: Persons with darker skin are often diagnosed at later stages when more difficult to treat, contributing to worse outcomes 7, 3
- Superficial spreading melanoma (SSM) is the most common subtype 8
- Ranks 17th in global cancer prevalence, with highest incidence in Europe, Australia, and New Zealand 5
Rare Variants and Subtypes
The evidence also identifies several less common cutaneous lymphomas and specialized skin cancers 9, 8:
Cutaneous T-cell Lymphomas (CTCL)
- Mycosis fungoides (most common CTCL subtype)
- Sézary syndrome
- Primary cutaneous CD30+ lymphoproliferative disorders
- Subcutaneous panniculitis-like T-cell lymphoma
Cutaneous B-cell Lymphomas (CBCL)
- Primary cutaneous marginal zone B-cell lymphoma
- Primary cutaneous follicle center lymphoma
- Primary cutaneous diffuse large B-cell lymphoma, leg type
Other Rare Forms
Key Clinical Distinctions
BCC characteristics: Develops from mutations in the PTCH gene system on chromosome 9q; associated with intensive UV exposure in childhood and adolescence 1, 6
SCC characteristics: Involves mutations in tumor suppressor gene p53 as an early event; related to chronic cumulative UV exposure; higher risk on genitalia, mucosal surfaces, and ears 1, 4
Melanoma characteristics: Associated with both intermittent and chronic sun exposure; closely linked to constitutive skin color and geographical location; BRAF mutations are common 10, 6
Epidemiological Context
More than 1 million cases of NMSC are diagnosed annually in the United States with rapidly rising incidence 1. The treatment cost for NMSC in the US Medicare population exceeds $400 million annually 1. Despite increasing incidence rates worldwide, mortality rates for both melanoma and keratinocyte cancers show stabilization or decline in some populations, likely due to earlier detection and improved treatments 6.