Basal Cell Carcinoma: Growth Rate and Prognosis
Basal cell carcinoma is a slow-growing, locally invasive malignancy with an excellent prognosis—metastasis occurs in less than 0.1% of cases, and mortality is extremely low, though untreated lesions can cause substantial local tissue destruction and disfigurement. 1, 2
Growth Characteristics
Growth Pattern and Timeline
- BCC typically exhibits slow, indolent growth over months to years, making it fundamentally different from more aggressive skin cancers 1, 3
- The tumor grows by local invasion rather than distant spread, with progressive enlargement at the primary site 1
- In the first years after presentation, BCC often causes no complaints or only minor symptoms, which contributes to delayed treatment in some patients 4
Morphological Behavior
- The tumor may ulcerate centrally as it enlarges, creating the classic "rodent ulcer" appearance 1
- Different histologic subtypes demonstrate varying growth patterns: nodular and superficial types grow more slowly and predictably, while infiltrative, morpheaform, sclerosing, and micronodular subtypes show more aggressive local invasion 1, 2
Prognosis
Overall Outcomes
- The prognosis for BCC is excellent, with cure rates exceeding 95-98% when appropriately treated 1
- Death from BCC is extraordinarily rare, occurring in less than 0.1% of cases 2
- The primary morbidity stems from local tissue destruction, disfigurement (particularly on the face), and functional impairment rather than mortality 1, 5
Recurrence Risk Stratification
The likelihood of recurrence depends on specific prognostic factors that should guide treatment selection 1:
High-risk features include:
- Tumor size ≥2 cm (increasing size confers progressively higher recurrence risk) 1
- High-risk anatomic locations: central face, periorbital areas, nose, lips, ears, chin, mandible 1, 2
- Poorly defined clinical margins 1
- Aggressive histologic subtypes: micronodular, infiltrative, sclerosing, morpheaform (desmoplastic) patterns 1, 2
- Perineural or perivascular invasion 1
- Recurrent tumors (previously treated lesions carry higher risk of further recurrence) 1
- Immunosuppression 1
Low-risk features include:
- Tumor size <2 cm 1
- Location on trunk or extremities (excluding pretibial area, hands, feet, ankles) 1
- Well-defined clinical margins 1
- Non-aggressive histologic subtypes: nodular, superficial, keratotic variant, infundibulocystic variant, fibroepithelioma of Pinkus 1
Critical Clinical Considerations
Basosquamous Carcinoma Exception
- Basosquamous carcinomas represent a distinct entity with metastatic potential more similar to squamous cell carcinoma than typical BCC 1, 2
- These biphenotypic tumors should be managed as squamous cell carcinomas due to their higher metastatic capacity 1
Treatment Outcomes by Modality
- Surgical excision with histologic margin assessment achieves 5-year disease-free rates exceeding 98% for appropriately selected BCCs 1
- Curettage and electrodesiccation yields 5-year cure rates of 91-97% for properly selected low-risk tumors 1
- For superficial BCC treated with imiquimod cream, complete clearance rates of 70-80% have been demonstrated, with 79% of patients remaining clinically clear at 2-year follow-up 6
Common Pitfalls
- Young age alone (<40 years) is NOT an independent risk factor for aggressive behavior—the histologic growth pattern determines risk regardless of patient age 1
- Patients who develop one BCC are at significantly increased risk of developing subsequent BCCs at other sites, necessitating long-term surveillance 1
- Approximately 6% of clinically clear superficial BCCs after treatment still harbor microscopic tumor on histologic examination 6
Active Surveillance Consideration
- For elderly patients with limited life expectancy and low-risk BCCs, active surveillance may be appropriate given the slow growth rate and low mortality risk 4
- This approach should be considered more frequently to avoid overtreatment in patients where immediate intervention offers minimal benefit to quality of life 4