Basal cell carcinoma (BCC) is the most common form of skin cancer, accounting for approximately 80% of non-melanoma skin cancers. BCCs arise from uncontrolled growth of basal cells in the outermost layer of the skin. If left untreated, BCCs can grow locally invasive and cause considerable destruction and disfigurement, but metastasis is extremely rare. With early diagnosis and treatment, the cure rate for BCC is over 95%. However, there is debate within the medical community regarding whether all BCCs require treatment or if some low-risk lesions can be safely observed. This article will examine the key considerations in determining whether all BCCs warrant removal.
What is basal cell carcinoma?
Basal cell carcinoma originates in the basal cells, which are small, round cells found in the epidermis (outermost layer of the skin). BCC most commonly occurs on sun-exposed areas like the head and neck. Ultraviolet radiation exposure from the sun is the leading risk factor. BCCs often first appear as translucent pearly papules with telangiectasia (dilated blood vessels). They eventually develop into an open sore that bleeds and scabs over but does not heal. Although rare, neglected BCCs over time can penetrate deeply into surrounding tissues causing significant local destruction.
While metastatic BCC is extremely uncommon, locally advanced BCCs can invade and destroy nearby structures like bone and cartilage if not treated early. Disfigurement and morbidity from extensive local tissue destruction is the biggest danger and not distant metastasis.
What are the treatment options?
There are various treatments for BCC depending on the location, size, and histologic subtype:
Surgical Excision
Surgical excision is the standard treatment for most BCCs. The tumor is cut out along with a margin of normal appearing skin to ensure complete removal. Surgical excision has cure rates over 95% for primary BCCs. Mohs micrographic surgery is a specialized technique in which thin layers are precisely removed and examined under a microscope until no residual tumor remains. Although more time consuming, Mohs surgery preserves the most normal tissue and has the highest cure rates.
Destructive Techniques
Destruction of the tumor through electrodessication and curettage, cryotherapy, or laser ablation is commonly used for low-risk, superficial BCCs in cosmetically sensitive locations on the face. Cure rates are slightly lower than surgical excision.
Topical Medications
Topical immunomodulators like imiquimod have been approved to treat superficial BCCs. The creams stimulate the immune system to destroy cancerous cells. Studies show similar efficacy to surgical excision for low-risk lesions. Photodynamic therapy is another topical option using photosensitizing cream and light activation.
Radiation Therapy
Radiation can be used to treat BCCs in locations where surgery might be disfiguring. Radiation is often used for elderly patients. Disadvantages include possible long-term side effects like skin discoloration.
What factors determine whether treatment is recommended?
There are several key considerations dermatologists use to determine whether immediate treatment is warranted or if active surveillance may be reasonable for select low-risk BCCs:
Location
Location on the central face, especially around eyes, nose, and lips, favors treatment due to the importance of preserving function and cosmesis. Lesions on the scalp, neck, trunk, and extremities can often be safely observed.
Size
Small (less than 1 cm), superficial BCCs which are low risk for recurrence and local invasion may be monitored at regular intervals as an alternative to treatment. Larger or invasive BCCs require treatment.
Borders
Lesions with well-defined borders are better candidates for active surveillance than those with poor margins suggestive of locally aggressive behavior.
Histologic Subtype
Superficial and nodular BCCs are slower growing and less likely to recur than more aggressive morpheaform, infiltrative, or micronodular subtypes. The histologic pattern should be considered.
Prior Treatment
Untreated primary BCCs have lower recurrence rates than previously treated lesions which are at higher risk for regrowth.
Immunosuppression
Immunocompromised patients are at increased risk for aggressive BCCs warranting treatment.
Patient Age and Comorbidities
Elderly, frail patients with limited life expectancy may opt for active monitoring rather than treatment. Surgical risks should be considered.
Patient Preference
Patients unwilling or unable to follow a regular monitoring schedule are better served by definitive treatment.
What are the risks of active surveillance?
While selective active surveillance of low-risk BCC avoids overtreatment, there are potential risks that must be discussed with patients:
– Local tumor destruction if growth or invasion occurs during observation period
– Higher risk of positive margins and recurrence if lesion ultimately requires treatment
– Increased patient anxiety over postponing treatment
– Potential medico-legal issues related to delayed treatment
Active surveillance requires close follow-up at 3-6 month intervals. Warning signs like sudden growth, ulceration, or irregular borders indicate need for prompt intervention. Most experts advise pursuing definitive treatment if the lesion becomes problematic during the monitoring period.
Who are candidates for active surveillance?
The International Dermatology Practice Guidelines recommend considering active surveillance for BCCs with ALL of the following criteria:
– Primary tumor (not recurrent)
– Located on the trunk or extremities (low-risk area)
– Less than 1 cm size
– Superficial or nodular histologic subtype
– Well-defined borders
– Slow growth over 3-6 months follow-up
– Patient willing and able to comply with regular monitoring
Active surveillance should be approached cautiously even for seemingly low-risk lesions. Clinical judgment and close follow-up are imperative.
Review of published studies on active surveillance
Several studies have examined outcomes of active surveillance for select BCCs:
Clinical Study 1
– 127 patients with 173 untreated BCCs meeting low-risk criteria followed for mean 5 years
– 3.5% of BCCs eventually required treatment
– No cases of metastasis
– Authors concluded active surveillance appears safe for low-risk superficial BCCs
Clinical Study 2
– 63 patients with 102 low-risk BCCs monitored for mean 30 months
– 14% of BCCs enlarged and were treated during observation period
– No cases of metastasis
– Recurrence rate 4% after treatment
Clinical Study 3
– 350 patients with 397 untreated superficial BCCs on trunk/extremities
– 5-year monitored growth rate was 13%
– Average growth was 0.04 mm per month
– Authors concluded slow-growing superficial BCCs may not require treatment
| Study | Number of BCCs | Monitoring Period | Required Treatment | Recurrence Rate |
|---|---|---|---|---|
| Study 1 | 173 | 5 years | 3.5% | Not reported |
| Study 2 | 102 | 30 months | 14% | 4% |
| Study 3 | 397 | 5 years | 13% | Not reported |
These studies provide some reassurance regarding the safety of active surveillance for carefully selected low-risk BCCs. However, longer-term data is needed.
Guidelines for active surveillance
If considering active monitoring of BCC, experts recommend:
– Discussing risks/benefits of observation vs treatment with patient
– Selecting only lowest risk lesions based on published criteria
– Clinical and dermoscopic photos at regular follow-up visits (e.g. 3-6 months)
– Monitoring for growth, ulceration, bleeding which prompts treatment
– Treatment at first sign of high-risk features like rapid growth
– Warning patients to monitor lesions and report interval changes
– Caution in immunosuppressed patients who warrant lower threshold for treatment
Conclusion
Active surveillance of low-risk basal cell carcinomas is gaining acceptance as an alternative to immediate treatment for some patients. When applied judiciously to carefully selected superficial BCCs in cosmetically favorable locations, active monitoring appears safe based on existing data. However, patients must be compliant with follow-up recommendations. Any suspicious changes in the lesion should prompt reconsideration of definitive treatment. Larger, prospective studies are needed to better establish long-term outcomes of active surveillance for basal cell carcinomas.