What is the most common type of tumor?

Basal Cell Carcinoma is the Most Common Tumor

Basal cell carcinoma (BCC) is the most common cancer in Europe, Australia, the USA, and worldwide. 1 This slow-growing, locally invasive malignant epidermal skin tumor predominantly affects Caucasians and rarely metastasizes, with morbidity resulting primarily from local tissue invasion and destruction.

Epidemiology and Incidence

BCC accounts for approximately 75% of all skin cancers 2. The incidence is showing a worldwide increase, with an estimated 3.6 million cases diagnosed annually 3. While accurate figures for the UK are difficult to obtain due to inconsistent data collection, the total number of skin cancers continues to rise, with projections indicating further increases up to the year 2040 1.

Risk Factors

Several key risk factors contribute to BCC development:

• Ultraviolet radiation exposure: The most significant etiological factor, particularly sun exposure during childhood 1
• Genetic predisposition: Especially in those with fair skin types I and II 1
• Age: Increasing age is associated with higher risk 1
• Gender: Males have higher incidence rates 1
• Immunosuppression: Compromised immune function increases risk 1
• Prior radiation exposure: Previous radiation therapy to the affected area 1
• Arsenic exposure: Environmental or occupational exposure 1

Clinical Presentation and Subtypes

BCC presents with diverse clinical appearances and morphology, including:

• Nodular: The most common subtype, often presenting as a pearly papule with telangiectasias 4
• Superficial: Typically appearing as erythematous patches or plaques 1
• Morphoeic/sclerosing: An aggressive variant with scar-like appearance 1
• Pigmented: Contains melanin, can be confused with melanoma 5
• Cystic: Presents with cystic components 1
• Micronodular and infiltrative: Associated with aggressive tissue invasion 1
• Basosquamous: A particularly aggressive variant 1

The head and neck are the most common sites, accounting for a significant proportion of cases, as these areas receive the most sun exposure 4.

Diagnosis

Dermatologists can make a confident clinical diagnosis in most cases, with diagnostic accuracy enhanced by:

• Good lighting and magnification
• Dermatoscopy
• Biopsy (when clinical doubt exists or to determine histological subtype)
• Advanced imaging techniques in selected cases (CT, MRI) 1

Newer diagnostic technologies such as optical coherence tomography, reflectance confocal microscopy, and exfoliative cytology may aid in diagnosis 2, 6.

Treatment Options

Treatment selection should be based on:

• Histological subtype
• Size and location of the lesion
• Patient factors (age, medical condition)
• Risk of recurrence
• Cosmetic considerations 4

Common treatment modalities include:

1. Surgical excision: Standard approach for most BCCs
2. Mohs micrographic surgery: Most effective for high-risk tumors
3. Electrodesiccation and curettage: For selected low-risk tumors
4. Cryosurgery: For superficial, well-defined lesions
5. Topical treatments: For superficial BCCs (imiquimod, 5-fluorouracil)
6. Radiation therapy: For older patients with contraindications to surgery
7. Systemic therapy: Hedgehog pathway inhibitors (vismodegib, sonidegib) for locally advanced or metastatic disease 2, 6

Prevention

Prevention strategies focus on:

• Sun protection measures (sunscreen, protective clothing, avoiding peak sun hours)
• Regular skin examinations
• Early detection and treatment of suspicious lesions
• Patient education about risk factors 1

Prognosis

While BCC has a low mortality rate due to its rare metastasis, it can cause significant morbidity through local tissue destruction, particularly on the face, head, and neck. Early detection and appropriate treatment lead to excellent outcomes in most cases 1.

Following development of a BCC, patients are at significantly increased risk of developing subsequent BCCs at other sites, necessitating ongoing surveillance 1.